1
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Aputen AD, Elias MG, Gilbert J, Sakoff JA, Gordon CP, Scott KF, Aldrich-Wright JR. Platinum(IV) Prodrugs Incorporating an Indole-Based Derivative, 5-Benzyloxyindole-3-Acetic Acid in the Axial Position Exhibit Prominent Anticancer Activity. Int J Mol Sci 2024; 25:2181. [PMID: 38396859 PMCID: PMC10888562 DOI: 10.3390/ijms25042181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 02/07/2024] [Accepted: 02/08/2024] [Indexed: 02/25/2024] Open
Abstract
Kinetically inert platinum(IV) complexes are a chemical strategy to overcome the impediments of standard platinum(II) antineoplastic drugs like cisplatin, oxaliplatin and carboplatin. In this study, we reported the syntheses and structural characterisation of three platinum(IV) complexes that incorporate 5-benzyloxyindole-3-acetic acid, a bioactive ligand that integrates an indole pharmacophore. The purity and chemical structures of the resultant complexes, P-5B3A, 5-5B3A and 56-5B3A were confirmed via spectroscopic means. The complexes were evaluated for anticancer activity against multiple human cell lines. All complexes proved to be considerably more active than cisplatin, oxaliplatin and carboplatin in most cell lines tested. Remarkably, 56-5B3A demonstrated the greatest anticancer activity, displaying GI50 values between 1.2 and 150 nM. Enhanced production of reactive oxygen species paired with the decline in mitochondrial activity as well as inhibition of histone deacetylase were also demonstrated by the complexes in HT29 colon cells.
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Affiliation(s)
- Angelico D. Aputen
- School of Science, Western Sydney University, Sydney, NSW 2751, Australia; (A.D.A.); (M.G.E.); (C.P.G.)
| | - Maria George Elias
- School of Science, Western Sydney University, Sydney, NSW 2751, Australia; (A.D.A.); (M.G.E.); (C.P.G.)
- Ingham Institute, Sydney, NSW 2170, Australia;
| | - Jayne Gilbert
- Calvary Mater Newcastle Hospital, Newcastle, NSW 2298, Australia; (J.G.); (J.A.S.)
| | - Jennette A. Sakoff
- Calvary Mater Newcastle Hospital, Newcastle, NSW 2298, Australia; (J.G.); (J.A.S.)
| | - Christopher P. Gordon
- School of Science, Western Sydney University, Sydney, NSW 2751, Australia; (A.D.A.); (M.G.E.); (C.P.G.)
| | - Kieran F. Scott
- Ingham Institute, Sydney, NSW 2170, Australia;
- School of Medicine, Western Sydney University, Sydney, NSW 2751, Australia
| | - Janice R. Aldrich-Wright
- School of Science, Western Sydney University, Sydney, NSW 2751, Australia; (A.D.A.); (M.G.E.); (C.P.G.)
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2
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Baz J, Khoury A, Elias MG, Mansour N, Mehanna S, Hammoud O, Gordon CP, Taleb RI, Aldrich-Wright JR, Daher CF. Enhanced potency of a chloro-substituted polyaromatic platinum(II) complex and its platinum(IV) prodrug against lung cancer. Chem Biol Interact 2024; 388:110834. [PMID: 38103879 DOI: 10.1016/j.cbi.2023.110834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 11/30/2023] [Accepted: 12/11/2023] [Indexed: 12/19/2023]
Abstract
The present study investigates the anti-neoplastic activity of a platinum (II) complex, Pt(II)5ClSS, and its platinum (IV) di-hydroxido analogue, Pt(IV)5ClSS, against mesenchymal cells (MCs), lung (A549), melanoma (A375) and breast (MDA-MB-231) cancer cells. Both complexes exhibited up to 14-fold improved cytotoxicity compared to cisplatin. NMR was used to determine that ∼25 % of Pt(IV)5ClSS was reduced to Pt(II)5ClSS in the presence of GSH (Glutathione) after 72 h. The complex 1H NMR spectra acquired for Pt(II)5ClSS with GSH shows evidence of degradation and environmental effects (∼30 %). The prominence of the 195Pt peak at ∼ -2800 ppm suggests that a significant amount of Pt(II)5ClSS remained in the mixture. Pt(II)5ClSS and Pt(IV)5ClSS have shown exceptional selectivity to cancer cells in comparison to MCs (IC50 > 150 μM). Western blot analysis of Pt(II)5ClSS and Pt(IV)5ClSS on A549 cells revealed significant upregulation of cleaved PARP-1, BAX/Bcl2 ratio, cleaved caspase 3 and cytochrome thus suggesting apoptosis was induced through the intrinsic pathway. Flow cytometry also revealed significant cell death by apoptosis. Treatment with Pt(II)5ClSS and Pt(IV)5ClSS also showed significant amounts of free radical production while the COMET assay showed that both complexes cause minimal DNA damage. Cellular uptake results via ICP-MS suggest a time-dependent active mode of transport for both complexes with Pt(II)5ClSS being transported at a higher rate compared to Pt(IV)5ClSS. A Dose Escalation Study carried out on BALB/c mice showed that Pt(II)5ClSS and Pt(IV)5ClSS were approximately 8- folds and 12.5-folds, respectively, more tolerated than cisplatin. The present study provides evidence that both complexes may have the characteristics of an efficient and potentially safe anti-tumor drug that could support NSCLC treatment.
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Affiliation(s)
- Joy Baz
- School of Arts and Sciences, Natural Sciences Department, Lebanese American University, Byblos, Mount Lebanon, Lebanon
| | - Aleen Khoury
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South, 2751, NSW, Australia
| | - Maria George Elias
- School of Arts and Sciences, Natural Sciences Department, Lebanese American University, Byblos, Mount Lebanon, Lebanon; School of Science, Western Sydney University, Locked Bag 1797, Penrith South, 2751, NSW, Australia
| | - Najwa Mansour
- School of Arts and Sciences, Natural Sciences Department, Lebanese American University, Byblos, Mount Lebanon, Lebanon
| | - Stephanie Mehanna
- School of Arts and Sciences, Natural Sciences Department, Lebanese American University, Byblos, Mount Lebanon, Lebanon
| | - Omar Hammoud
- School of Arts and Sciences, Natural Sciences Department, Lebanese American University, Byblos, Mount Lebanon, Lebanon
| | - Christopher P Gordon
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South, 2751, NSW, Australia
| | - Robin I Taleb
- School of Arts and Sciences, Natural Sciences Department, Lebanese American University, Byblos, Mount Lebanon, Lebanon
| | - Janice R Aldrich-Wright
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South, 2751, NSW, Australia.
| | - Costantine F Daher
- School of Arts and Sciences, Natural Sciences Department, Lebanese American University, Byblos, Mount Lebanon, Lebanon.
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3
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McGhie BS, Sakoff J, Gilbert J, Gordon CP, Aldrich-Wright JR. Synthesis and Characterisation of Platinum(II) Diaminocyclohexane Complexes with Pyridine Derivatives as Anticancer Agents. Int J Mol Sci 2023; 24:17150. [PMID: 38138979 PMCID: PMC10742472 DOI: 10.3390/ijms242417150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 11/30/2023] [Accepted: 12/03/2023] [Indexed: 12/24/2023] Open
Abstract
Cisplatin-type covalent chemotherapeutics are a cornerstone of modern medicinal oncology. However, these drugs remain encumbered with dose-limiting side effects and are susceptible to innate and acquired resistance. The bulk of platinum anticancer research has focused on Cisplatin and its derivatives. Here, we take inspiration from the design of platinum complexes and ligands used successfully with other metals to create six novel complexes. Herein, the synthesis, characterization, DNA binding affinities, and lipophilicity of a series of non-traditional organometallic Pt(II)-complexes are described. These complexes have a basic [Pt(PL)(AL)]Cl2 molecular formula which incorporates either 2-pyrrolidin-2-ylpyridine, 2-(1H-Imidazol-2-yl)pyridine, or 2-(2-pyridyl)benzimidazole as the PL; the AL is resolved diaminocyclohexane. Precursor [Pt(PL)(Cl)2] complexes were also characterized for comparison. While the cytotoxicity and DNA binding properties of the three precursors were unexceptional, the corresponding [Pt(PL)(AL)]2+ complexes were promising; they exhibited different DNA binding interactions compared with Cisplatin but with similar, if not slightly better, cytotoxicity results. Complexes with 2-pyrrolidin-2-ylpyridine or 2-(2-pyridyl)benzimidazole ligands had similar DNA binding properties to those with 2-(1H-Imidazol-2-yl)pyridine ligands but were not as cytotoxic to all cell lines. The variation in activity between cell lines was remarkable and resulted in significant selectivity indices in MCF10A and MCF-7 breast cancer cell lines, compared with previously described similar Pt(II) complexes such as 56MESS.
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Affiliation(s)
- Brondwyn S. McGhie
- Nanoscale Organisation and Dynamics Group, School of Science, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia; (B.S.M.); (C.P.G.)
| | - Jennette Sakoff
- Department of Medical Oncology, Calvary Mater Newcastle Hospital, Waratah, NSW 2298, Australia; (J.S.); (J.G.)
| | - Jayne Gilbert
- Department of Medical Oncology, Calvary Mater Newcastle Hospital, Waratah, NSW 2298, Australia; (J.S.); (J.G.)
| | - Christopher P. Gordon
- Nanoscale Organisation and Dynamics Group, School of Science, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia; (B.S.M.); (C.P.G.)
| | - Janice R. Aldrich-Wright
- Nanoscale Organisation and Dynamics Group, School of Science, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia; (B.S.M.); (C.P.G.)
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4
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McGhie BS, Sakoff J, Gilbert J, Gordon CP, Aldrich-Wright JR. Synthesis and Characterisation of Fluorescent Novel Pt(II) Cyclometallated Complexes with Anticancer Activity. Int J Mol Sci 2023; 24:ijms24098049. [PMID: 37175756 PMCID: PMC10178562 DOI: 10.3390/ijms24098049] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 04/20/2023] [Accepted: 04/25/2023] [Indexed: 05/15/2023] Open
Abstract
Cancer poses a significant threat to global health and new treatments are required to improve the prognosis for patients. Previously, unconventional platinum complexes designed to incorporate polypyridyl ligands paired with diaminocyclohexane have demonstrated anticancer activity in KRAS mutated cells, previously thought to be undruggable and have cytotoxicity values up to 100 times better than cisplatin. In this work, these complexes were used as inspiration to design six novel cyclometallated examples, whose fluorescence could be exploited to better understand the mechanism of action of these kinds of platinum drugs. The cytotoxicity results revealed that these cyclometallated complexes (CMCs) have significantly different activity compared to the complexes that inspired them; they are as cytotoxic as cisplatin and have much higher selectivity indices in breast cancer cell lines (MCF10A/MCF-7). Complexes 1b, 2a, and 3b all had very high selectivity indexes compared to previous Pt(II) complexes. This prompted further investigation into their DNA binding properties, which revealed that they had good affinity to ctDNA, especially CMCs 1a and 3b. Their inherent fluorescence was successfully utilised in the calculation of their DNA binding affinity and could be useful in future work.
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Affiliation(s)
- Brondwyn S McGhie
- School of Science, Nanoscale Organisation and Dynamics Group, Western Sydney University, Locked Bag 1797 Penrith South DC, Penrith, NSW 2751, Australia
| | - Jennette Sakoff
- Calvary Mater Newcastle, Waratah, Newcastle, NSW 2298, Australia
| | - Jayne Gilbert
- Calvary Mater Newcastle, Waratah, Newcastle, NSW 2298, Australia
| | - Christopher P Gordon
- School of Science, Nanoscale Organisation and Dynamics Group, Western Sydney University, Locked Bag 1797 Penrith South DC, Penrith, NSW 2751, Australia
| | - Janice R Aldrich-Wright
- School of Science, Nanoscale Organisation and Dynamics Group, Western Sydney University, Locked Bag 1797 Penrith South DC, Penrith, NSW 2751, Australia
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5
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Aputen AD, Elias MG, Gilbert J, Sakoff JA, Gordon CP, Scott KF, Aldrich-Wright JR. Versatile Platinum(IV) Prodrugs of Naproxen and Acemetacin as Chemo-Anti-Inflammatory Agents. Cancers (Basel) 2023; 15:cancers15092460. [PMID: 37173934 PMCID: PMC10177380 DOI: 10.3390/cancers15092460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 04/22/2023] [Accepted: 04/23/2023] [Indexed: 05/15/2023] Open
Abstract
Developing new and versatile platinum(IV) complexes that incorporate bioactive moieties is a rapidly evolving research strategy for cancer drug discovery. In this study, six platinum(IV) complexes (1-6) that are mono-substituted in the axial position with a non-steroidal anti-inflammatory molecule, naproxen or acemetacin, were synthesised. A combination of spectroscopic and spectrometric techniques confirmed the composition and homogeneity of 1-6. The antitumour potential of the resultant complexes was assessed on multiple cell lines and proved to be significantly improved compared with cisplatin, oxaliplatin and carboplatin. The platinum(IV) derivatives conjugated with acemetacin (5 and 6) were determined to be the most biologically potent, demonstrating GI50 values ranging between 0.22 and 250 nM. Remarkably, in the Du145 prostate cell line, 6 elicited a GI50 value of 0.22 nM, which is 5450-fold more potent than cisplatin. A progressive decrease in reactive oxygen species and mitochondrial activity was observed for 1-6 in the HT29 colon cell line, up to 72 h. The inhibition of the cyclooxygenase-2 enzyme was also demonstrated by the complexes, confirming that these platinum(IV) complexes may reduce COX-2-dependent inflammation and cancer cell resistance to chemotherapy.
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Affiliation(s)
- Angelico D Aputen
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South, Sydney, NSW 2751, Australia
| | - Maria George Elias
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South, Sydney, NSW 2751, Australia
- Ingham Institute, Liverpool, Sydney, NSW 2170, Australia
| | - Jayne Gilbert
- Calvary Mater Newcastle Hospital, Waratah, Newcastle, NSW 2298, Australia
| | - Jennette A Sakoff
- Calvary Mater Newcastle Hospital, Waratah, Newcastle, NSW 2298, Australia
| | - Christopher P Gordon
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South, Sydney, NSW 2751, Australia
| | - Kieran F Scott
- Ingham Institute, Liverpool, Sydney, NSW 2170, Australia
- School of Medicine, Western Sydney University, Locked Bag 1797, Penrith South, Sydney, NSW 2751, Australia
| | - Janice R Aldrich-Wright
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South, Sydney, NSW 2751, Australia
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6
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Khoury A, Elias E, Mehanna S, Shebaby W, Deo KM, Mansour N, Khalil C, Sayyed K, Sakoff JA, Gilbert J, Daher CF, Gordon CP, Taleb RI, Aldrich-Wright JR. Novel Platinum(II) and Platinum(IV) Antitumor Agents that Exhibit Potent Cytotoxicity and Selectivity. J Med Chem 2022; 65:16481-16493. [PMID: 36480933 DOI: 10.1021/acs.jmedchem.2c01310] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A novel platinum(II) complex 47OMESS(II) and its platinum(IV) derivative 47OMESS(IV) were synthesized and characterized. Cytotoxicity studies against mesenchymal cells (MCs) and lung (A549), breast (MDA-MB-231), and melanoma (A375) cancer cells demonstrated 7-20-fold superior activity for both complexes relative to cisplatin. Remarkably, 47OMESS(IV) demonstrated 17-22-fold greater selectivity toward the cancerous cells compared to the non-cancerous MCs. Western blot analysis on A549 cells showed the involvement of the intrinsic apoptotic pathway. Cellular fractionation and uptake experiments in A549 cells using ICP-mass spectrometry (MS) indicated that 47OMESS(II) and 47OMESS(IV) cross the cellular membrane predominantly via active transport mechanisms. The significant improvement in selectivity that is exhibited by 47OMESS(IV) is reported for the first time for this class of complexes.
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Affiliation(s)
- Aleen Khoury
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South, NSW 2751, Australia
| | - Elias Elias
- School of Natural Sciences, School of Arts and Sciences, Lebanese American University, P.O. Box 36, Byblos Lebanon
| | - Stephanie Mehanna
- School of Natural Sciences, School of Arts and Sciences, Lebanese American University, P.O. Box 36, Byblos Lebanon
| | - Wassim Shebaby
- School of Natural Sciences, School of Arts and Sciences, Lebanese American University, P.O. Box 36, Byblos Lebanon
| | - Krishant M Deo
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South, NSW 2751, Australia
| | - Najwa Mansour
- School of Natural Sciences, School of Arts and Sciences, Lebanese American University, P.O. Box 36, Byblos Lebanon
| | - Christian Khalil
- School of Natural Sciences, School of Arts and Sciences, Lebanese American University, P.O. Box 36, Byblos Lebanon
| | - Katia Sayyed
- School of Natural Sciences, School of Arts and Sciences, Lebanese American University, P.O. Box 36, Byblos Lebanon
| | | | - Jayne Gilbert
- Calvary Mater Newcastle Hospital, Waratah, NSW 2298, Australia
| | - Costantine F Daher
- School of Natural Sciences, School of Arts and Sciences, Lebanese American University, P.O. Box 36, Byblos Lebanon
| | - Christopher P Gordon
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South, NSW 2751, Australia
| | - Robin I Taleb
- School of Natural Sciences, School of Arts and Sciences, Lebanese American University, P.O. Box 36, Byblos Lebanon
| | - Janice R Aldrich-Wright
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South, NSW 2751, Australia
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7
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Khoury A, Sakoff JA, Gilbert J, Karan S, Gordon CP, Aldrich-Wright JR. Potent Platinum(IV) Prodrugs That Incorporate a Biotin Moiety to Selectively Target Cancer Cells. Pharmaceutics 2022; 14:pharmaceutics14122780. [PMID: 36559273 PMCID: PMC9853328 DOI: 10.3390/pharmaceutics14122780] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 11/28/2022] [Accepted: 12/09/2022] [Indexed: 12/15/2022] Open
Abstract
Four platinum(IV) prodrugs incorporating a biotin moiety to selectively target cancer cells were synthesised, characterised, and their biological activity assessed. All complexes exhibited exceptional in vitro cytotoxicity against a panel of cancer cell lines, with [Pt(5,6-dimethyl-1,10-phenanthroline)(1S,2S-diaminocyclohexane)(biotin)(hydroxido)](NO3)2, (2) exhibiting the lowest GI50 of 4 nM in the prostate Du145 cancer cell line. Each complex displayed significantly enhanced activity compared to cisplatin, with 2 being 1000-fold more active in the HT29 colon cancer cell line. Against the MCF-7 breast cancer cell line, in which high levels of biotin receptors are expressed, 2, [Pt(4,7-dimethoxy-1,10-phenanthroline)(1S,2S-diaminocyclohexane)(biotin)(hydroxido)](NO3)2, (3), and [Pt(5-methyl-1,10-phenanthroline)(1S,2S-diaminocyclohexane)(biotin)(hydroxido)](NO3)2, (4) exhibited enhanced activity compared to their platinum(II) cores, with 4 being 6-fold more active than its platinum(II) precursor. Furthermore, 3 exhibited 3-fold greater selectivity towards MCF-7 breast cancer cells compared to MCF10A breast healthy cells, and this was further confirmed by platinum uptake studies, which showed 3 to have almost 3-fold greater uptake in MCF-7 cells, compared to MCF10A cells. The results show that lipophilicity and selectivity both contributed to the cellular uptake of 1-4; however, this was not always translated to the observed cytotoxicity.
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Affiliation(s)
- Aleen Khoury
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South DC, NSW 2751, Australia
| | | | - Jayne Gilbert
- Calvary Mater Hospital, Waratah, NSW 2298, Australia
| | - Shawan Karan
- Teaching and Research Technical Services, Western Sydney University, Locked Bag 1797, Penrith South DC, NSW 2751, Australia
| | - Christopher P. Gordon
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South DC, NSW 2751, Australia
| | - Janice R. Aldrich-Wright
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South DC, NSW 2751, Australia
- Correspondence: ; Tel.: +61-246-203-218
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8
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Aputen AD, Elias MG, Gilbert J, Sakoff JA, Gordon CP, Scott KF, Aldrich-Wright JR. Bioactive Platinum(IV) Complexes Incorporating Halogenated Phenylacetates. Molecules 2022; 27:molecules27207120. [PMID: 36296713 PMCID: PMC9611758 DOI: 10.3390/molecules27207120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 10/14/2022] [Accepted: 10/17/2022] [Indexed: 11/17/2022]
Abstract
A new series of cytotoxic platinum(IV) complexes (1-8) incorporating halogenated phenylacetic acid derivatives (4-chlorophenylacetic acid, 4-fluorophenylacetic acid, 4-bromophenylacetic acid and 4-iodophenylacetic acid) were synthesised and characterised using spectroscopic and spectrometric techniques. Complexes 1-8 were assessed on a panel of cell lines including HT29 colon, U87 glioblastoma, MCF-7 breast, A2780 ovarian, H460 lung, A431 skin, Du145 prostate, BE2-C neuroblastoma, SJ-G2 glioblastoma, MIA pancreas, the ADDP-resistant ovarian variant, and the non-tumour-derived MCF10A breast line. The in vitro cytotoxicity results confirmed the superior biological activity of the studied complexes, especially those containing 4-fluorophenylacetic acid and 4-bromophenylacetic acid ligands, namely 4 and 6, eliciting an average GI50 value of 20 nM over the range of cell lines tested. In the Du145 prostate cell line, 4 exhibited the highest degree of potency amongst the derivatives, displaying a GI50 value of 0.7 nM, which makes it 1700-fold more potent than cisplatin (1200 nM) and nearly 7-fold more potent than our lead complex, 56MESS (4.6 nM) in this cell line. Notably, in the ADDP-resistant ovarian variant cell line, 4 (6 nM) was found to be almost 4700-fold more potent than cisplatin. Reduction reaction experiments were also undertaken, along with studies aimed at determining the complexes' solubility, stability, lipophilicity, and reactive oxygen species production.
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Affiliation(s)
- Angelico D. Aputen
- School of Science, Western Sydney University, Locked Bag 1797, Sydney, NSW 2751, Australia
| | - Maria George Elias
- School of Science, Western Sydney University, Locked Bag 1797, Sydney, NSW 2751, Australia
- Ingham Institute, Sydney, NSW 2170, Australia
| | - Jayne Gilbert
- Calvary Mater Newcastle Hospital, Newcastle, NSW 2298, Australia
| | | | - Christopher P. Gordon
- School of Science, Western Sydney University, Locked Bag 1797, Sydney, NSW 2751, Australia
| | | | - Janice R. Aldrich-Wright
- School of Science, Western Sydney University, Locked Bag 1797, Sydney, NSW 2751, Australia
- Correspondence: ; Tel.: +61-246203218
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9
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Aputen AD, Elias MG, Gilbert J, Sakoff JA, Gordon CP, Scott KF, Aldrich-Wright JR. Potent Chlorambucil-Platinum(IV) Prodrugs. Int J Mol Sci 2022; 23:ijms231810471. [PMID: 36142383 PMCID: PMC9499463 DOI: 10.3390/ijms231810471] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 08/30/2022] [Accepted: 09/06/2022] [Indexed: 11/16/2022] Open
Abstract
The DNA-alkylating derivative chlorambucil was coordinated in the axial position to atypical cytotoxic, heterocyclic, and non-DNA coordinating platinum(IV) complexes of type, [PtIV(HL)(AL)(OH)2](NO3)2 (where HL is 1,10-phenanthroline, 5-methyl-1,10-phenanthroline or 5,6-dimethyl-1,10-phenanthroline, AL is 1S,2S-diaminocyclohexane). The resultant platinum(IV)-chlorambucil prodrugs, PCLB, 5CLB, and 56CLB, were characterized using high-performance liquid chromatography, nuclear magnetic resonance, ultraviolet-visible, circular dichroism spectroscopy, and electrospray ionization mass spectrometry. The prodrugs displayed remarkable antitumor potential across multiple human cancer cell lines compared to chlorambucil, cisplatin, oxaliplatin, and carboplatin, as well as their platinum(II) precursors, PHENSS, 5MESS, and 56MESS. Notably, 56CLB was exceptionally potent in HT29 colon, Du145 prostate, MCF10A breast, MIA pancreas, H460 lung, A2780, and ADDP ovarian cell lines, with GI50 values ranging between 2.7 and 21 nM. Moreover, significant production of reactive oxygen species was detected in HT29 cells after treatment with PCLB, 5CLB, and 56CLB up to 72 h compared to chlorambucil and the platinum(II) and (IV) precursors.
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Affiliation(s)
- Angelico D. Aputen
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South DC, Sydney, NSW 2751, Australia
| | - Maria George Elias
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South DC, Sydney, NSW 2751, Australia
- Ingham Institute, Liverpool, NSW 2170, Australia
| | - Jayne Gilbert
- Calvary Mater Hospital, Waratah, NSW 2298, Australia
| | | | - Christopher P. Gordon
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South DC, Sydney, NSW 2751, Australia
| | | | - Janice R. Aldrich-Wright
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South DC, Sydney, NSW 2751, Australia
- Correspondence: ; Tel.: +61-246203218
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10
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Biberger T, Nöthling N, Leutzsch M, Gordon CP, Copéret C, Fürstner A. An Anionic Dinuclear Ruthenium Dihydrogen Complex of Relevance for Alkyne
gem
‐Hydrogenation. Angew Chem Int Ed Engl 2022; 61:e202201311. [PMID: 35363926 PMCID: PMC9322539 DOI: 10.1002/anie.202201311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Indexed: 11/12/2022]
Abstract
During an investigation into the fate of ruthenium precatalysts used for light‐driven alkyne gem‐hydrogenation reactions with formation of Grubbs‐type ruthenium catalysts, it was found that the reaction of [(IPr)(η6‐cymene)RuCl2] with H2 under UV‐irradiation affords an anionic dinuclear σ‐dihydrogen complex, which is thermally surprisingly robust. Not only are anionic σ‐complexes in general exceedingly rare, but the newly formed species seems to be the first example lacking any structural attributes able to counterbalance the negative charge and, in so doing, prevent oxidative insertion of the metal centers into the ligated H2 from occurring.
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Affiliation(s)
- Tobias Biberger
- Max-Planck-Institut für Kohlenforschung 45470 Mülheim/Ruhr Germany
| | - Nils Nöthling
- Max-Planck-Institut für Kohlenforschung 45470 Mülheim/Ruhr Germany
| | - Markus Leutzsch
- Max-Planck-Institut für Kohlenforschung 45470 Mülheim/Ruhr Germany
| | - Christopher P. Gordon
- Department of Chemistry and Applied Biosciences, ETH Zürich Vladimir-Prelog-Weg 1–5 8093 Zürich Switzerland
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences, ETH Zürich Vladimir-Prelog-Weg 1–5 8093 Zürich Switzerland
| | - Alois Fürstner
- Max-Planck-Institut für Kohlenforschung 45470 Mülheim/Ruhr Germany
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11
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Khoury A, Sakoff JA, Gilbert J, Scott KF, Karan S, Gordon CP, Aldrich-Wright JR. Cyclooxygenase-Inhibiting Platinum(IV) Prodrugs with Potent Anticancer Activity. Pharmaceutics 2022; 14:pharmaceutics14040787. [PMID: 35456621 PMCID: PMC9029360 DOI: 10.3390/pharmaceutics14040787] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 03/30/2022] [Accepted: 03/30/2022] [Indexed: 01/27/2023] Open
Abstract
Platinum(IV) prodrugs of the [Pt(PL)(AL)(COXi)(OH)]2+ type scaffold (where PL is 1,10-phenanthroline or 5,6-dimethyl-1,10-phenanthroline, AL is 1S,2S-diaminocyclohexane, and COXi is a COX inhibitor, either indomethacin or aspirin) were synthesised and characterised, and their biological activity was explored. MTT assays showed that these complexes exhibit outstanding activity against a range of cancer cell lines, and nanomolar activities were observed. The most potent complex, 4, exhibited a GI50 of 3 nM in the Du145 prostate cancer cell line and was observed to display a 1614-fold increased activity against the HT29 colon cancer cell line relative to cisplatin. ICP-MS studies showed a linear correlation between increased cellular accumulation of the complexes and increased cytotoxicity, while an enzyme immunoassay showed that 1 and 2 inhibited COX-2 at 14 and 1.4 µM, respectively, which is comparable to the inhibition exhibited by indomethacin. These results suggest that while the cytotoxicity of prodrugs 1–4 was influenced by cellular uptake, it was not entirely dependent on either COX inhibition or lipophilicity.
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Affiliation(s)
- Aleen Khoury
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South, NSW 2751, Australia; (A.K.); (S.K.); (C.P.G.)
| | | | - Jayne Gilbert
- Calvary Mater Hospital, Waratah, NSW 2298, Australia; (J.A.S.); (J.G.)
| | - Kieran F. Scott
- School of Medicine, Western Sydney University, Locked Bag 1797, Penrith South, NSW 2751, Australia;
- Ingham Institute, 1 Campbell Street, Liverpool, NSW 2170, Australia
| | - Shawan Karan
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South, NSW 2751, Australia; (A.K.); (S.K.); (C.P.G.)
| | - Christopher P. Gordon
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South, NSW 2751, Australia; (A.K.); (S.K.); (C.P.G.)
| | - Janice R. Aldrich-Wright
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South, NSW 2751, Australia; (A.K.); (S.K.); (C.P.G.)
- Correspondence: ; Tel.: +61-246203218
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12
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Biberger T, Nöthling N, Leutzsch M, Gordon CP, Copéret C, Fürstner A. An Anionic Dinuclear Ruthenium Dihydrogen Complex of Relevance for Alkyne gem‐Hydrogenation. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202201311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Tobias Biberger
- Max-Planck-Institut für Kohlenforschung: Max-Planck-Institut fur Kohlenforschung Organometallc Chemistry 45470 Mülheim/Ruhr GERMANY
| | - Nils Nöthling
- Max-Planck-Institut für Kohlenforschung: Max-Planck-Institut fur Kohlenforschung Chemical Crystallography 45470 Mülheim/Ruhr GERMANY
| | - Markus Leutzsch
- Max-Planck-Institut für Kohlenforschung: Max-Planck-Institut fur Kohlenforschung NMR Spectroscopy 45470 Mülheim/Ruhr GERMANY
| | - Christopher P. Gordon
- ETH Zürich: Eidgenossische Technische Hochschule Zurich Inorganic Chemistry 8093 Zürich SWITZERLAND
| | - Christophe Copéret
- ETH Zürich: Eidgenossische Technische Hochschule Zurich Inorganic Chemistry 8093 Zürich SWITZERLAND
| | - Alois Fürstner
- Max-Planck-Institut fur Kohlenforschung Organometallic Chemistry Kaiser-Wilhelm-Platz 1 45470 Mülheim/Ruhr GERMANY
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13
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Menti-Platten M, Aldrich-Wright JR, Gordon CP. A flow-based transition-metal-catalysed hydrogenolysis strategy to facilitate peptide side-chain deprotection. Org Biomol Chem 2021; 20:106-112. [PMID: 34897363 DOI: 10.1039/d1ob02179f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Orthogonal deprotection methodologies are an invaluable tool for the construction of site-specially modified peptides. Here, we report a facile 10% Pd/CaCO3-based procedure to selectively mediate Nβ-side-chain Cbz-lysis from extended peptide sequences in the presence of trityl and t-Butyl protecting groups.
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Affiliation(s)
- Maria Menti-Platten
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South DC, Australia.
| | - Janice R Aldrich-Wright
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South DC, Australia. .,Nanoscale Organisation and Dynamics Group, Locked Bag 1797, Penrith South DC, Australia
| | - Christopher P Gordon
- School of Science, Western Sydney University, Locked Bag 1797, Penrith South DC, Australia. .,Nanoscale Organisation and Dynamics Group, Locked Bag 1797, Penrith South DC, Australia.,Molecular Medicine Research Group, Western Sydney University School of Medicine, Narellan Rd & Gilchrist Dr, 2560, Campbelltown, NSW, Australia
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14
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Tadros J, Dankers C, Aldrich‐Wright JR, Polyzos A, Gordon CP. A Solid‐Phase Assisted Flow Approach to
In Situ
Wittig‐Type Olefination Coupling. European J Org Chem 2021. [DOI: 10.1002/ejoc.202100761] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Joseph Tadros
- School of Science Western Sydney University 1797 Locked Bag Penrith South DC Australia
| | - Christian Dankers
- School of Science Western Sydney University 1797 Locked Bag Penrith South DC Australia
| | - Janice R. Aldrich‐Wright
- School of Science Western Sydney University 1797 Locked Bag Penrith South DC Australia
- Nanoscale Organisation and Dynamics Group Western Sydney University 1797 Locked Bag Penrith South DC Australia
| | - Anastasios Polyzos
- CSIRO Manufacturing The Commonwealth Scientific and Industrial Research Organisation Research Way 3168 Clayton Victoria Australia
- School of Chemistry The University of Melbourne 3010 Melbourne Victoria Australia
| | - Christopher P. Gordon
- School of Science Western Sydney University 1797 Locked Bag Penrith South DC Australia
- Nanoscale Organisation and Dynamics Group Western Sydney University 1797 Locked Bag Penrith South DC Australia
- Molecular Medicine Research Group Nanoscale Organisation and Dynamics Group Western Sydney University School of Medicine Narellan Road & Gilchrist Drive 2560 Campbelltown NSW Australia
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15
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Gordon CP, Lätsch L, Copéret C. Nuclear Magnetic Resonance: A Spectroscopic Probe to Understand the Electronic Structure and Reactivity of Molecules and Materials. J Phys Chem Lett 2021; 12:2072-2085. [PMID: 33617260 DOI: 10.1021/acs.jpclett.0c03520] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
This Perspective focuses on the ability of chemical shift to identify and characterize the electronic structure and associated reactivity of molecules and materials. After a general introduction on NMR parameters, we will show selected examples where the chemical shift of various NMR active nuclei has been used to investigate and understand electronic properties, with a particular focus on organometallic compounds and inorganic materials with relevance to catalysis. We will demonstrate how the NMR parameter of probe molecules and ligands can be used to elucidate the nature of active sites and how they can help to understand and predict their reactivity. Lastly, we will give an overview over recent advances in deciphering metal NMR parameters. Overall, we show how chemical shift is a reactivity descriptor that can be analyzed and understood on a molecular level.
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Affiliation(s)
- Christopher P Gordon
- ETH Zurich, Department of Chemistry and Applied Biosciences, Vladimir-Prelog-Weg 2, Zurich, Switzerland
| | - Lukas Lätsch
- ETH Zurich, Department of Chemistry and Applied Biosciences, Vladimir-Prelog-Weg 2, Zurich, Switzerland
| | - Christophe Copéret
- ETH Zurich, Department of Chemistry and Applied Biosciences, Vladimir-Prelog-Weg 2, Zurich, Switzerland
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16
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Engler H, Lansing M, Gordon CP, Neudörfl JM, Schäfer M, Schlörer NE, Copéret C, Berkessel A. Olefin Epoxidation Catalyzed by Titanium–Salalen Complexes: Synergistic H 2O 2 Activation by Dinuclear Ti Sites, Ligand H-Bonding, and π-Acidity. ACS Catal 2021. [DOI: 10.1021/acscatal.0c05320] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Hauke Engler
- Department of Chemistry, Cologne University, Greinstraße 4, 50939 Cologne, Germany
| | - Markus Lansing
- Department of Chemistry, Cologne University, Greinstraße 4, 50939 Cologne, Germany
| | - Christopher P. Gordon
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Jörg-M. Neudörfl
- Department of Chemistry, Cologne University, Greinstraße 4, 50939 Cologne, Germany
| | - Mathias Schäfer
- Department of Chemistry, Cologne University, Greinstraße 4, 50939 Cologne, Germany
| | - Nils E. Schlörer
- Department of Chemistry, Cologne University, Greinstraße 4, 50939 Cologne, Germany
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich, Switzerland
| | - Albrecht Berkessel
- Department of Chemistry, Cologne University, Greinstraße 4, 50939 Cologne, Germany
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17
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Copéret C, Berkson ZJ, Chan KW, de Jesus Silva J, Gordon CP, Pucino M, Zhizhko PA. Olefin metathesis: what have we learned about homogeneous and heterogeneous catalysts from surface organometallic chemistry? Chem Sci 2021; 12:3092-3115. [PMID: 34164078 PMCID: PMC8179417 DOI: 10.1039/d0sc06880b] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 02/08/2021] [Indexed: 11/21/2022] Open
Abstract
Since its early days, olefin metathesis has been in the focus of scientific discussions and technology development. While heterogeneous olefin metathesis catalysts based on supported group 6 metal oxides have been used for decades in the petrochemical industry, detailed mechanistic studies and the development of molecular organometallic chemistry have led to the development of robust and widely used homogeneous catalysts based on well-defined alkylidenes that have found applications for the synthesis of fine and bulk chemicals and are also used in the polymer industry. The development of the chemistry of high-oxidation group 5-7 alkylidenes and the use of surface organometallic chemistry (SOMC) principles unlocked the preparation of so-called well-defined supported olefin metathesis catalysts. The high activity and stability (often superior to their molecular analogues) and molecular-level characterisation of these systems, that were first reported in 2001, opened the possibility for the first direct structure-activity relationships for supported metathesis catalysts. This review describes first the history of SOMC in the field of olefin metathesis, and then focuses on what has happened since 2007, the date of our last comprehensive reviews in this field.
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Affiliation(s)
- Christophe Copéret
- ETH Zürich, Department of Chemistry and Applied Biosciences Vladimir Prelog Weg 2 CH-8093 Zürich Switzerland
| | - Zachariah J Berkson
- ETH Zürich, Department of Chemistry and Applied Biosciences Vladimir Prelog Weg 2 CH-8093 Zürich Switzerland
| | - Ka Wing Chan
- ETH Zürich, Department of Chemistry and Applied Biosciences Vladimir Prelog Weg 2 CH-8093 Zürich Switzerland
| | - Jordan de Jesus Silva
- ETH Zürich, Department of Chemistry and Applied Biosciences Vladimir Prelog Weg 2 CH-8093 Zürich Switzerland
| | - Christopher P Gordon
- ETH Zürich, Department of Chemistry and Applied Biosciences Vladimir Prelog Weg 2 CH-8093 Zürich Switzerland
| | - Margherita Pucino
- ETH Zürich, Department of Chemistry and Applied Biosciences Vladimir Prelog Weg 2 CH-8093 Zürich Switzerland
| | - Pavel A Zhizhko
- A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences Vavilov Str. 28 119991 Moscow Russia
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18
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Jackl MK, Gordon CP, Copéret C, Bode JW. Spirocyclic Nitroxide Biradicals: Synthesis and Evaluation as Dynamic Nuclear Polarizing Agents. Helv Chim Acta 2020. [DOI: 10.1002/hlca.202000179] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Moritz K. Jackl
- Department of Chemistry and Applied Bioscience ETH Zürich CH-8093 Zürich Switzerland
| | - Christopher P. Gordon
- Department of Chemistry and Applied Bioscience ETH Zürich CH-8093 Zürich Switzerland
| | - Christophe Copéret
- Department of Chemistry and Applied Bioscience ETH Zürich CH-8093 Zürich Switzerland
| | - Jeffrey W. Bode
- Department of Chemistry and Applied Bioscience ETH Zürich CH-8093 Zürich Switzerland
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19
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Hillenbrand J, Leutzsch M, Gordon CP, Copéret C, Fürstner A. 183 W NMR Spectroscopy Guides the Search for Tungsten Alkylidyne Catalysts for Alkyne Metathesis. Angew Chem Int Ed Engl 2020; 59:21758-21768. [PMID: 32820864 PMCID: PMC7756321 DOI: 10.1002/anie.202009975] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 08/21/2020] [Indexed: 12/12/2022]
Abstract
Triarylsilanolates are privileged ancillary ligands for molybdenum alkylidyne catalysts for alkyne metathesis but lead to disappointing results and poor stability in the tungsten series. 1 H,183 W heteronuclear multiple bond correlation spectroscopy, exploiting a favorable 5 J-coupling between the 183 W center and the peripheral protons on the alkylidyne cap, revealed that these ligands upregulate the Lewis acidity to an extent that the tungstenacyclobutadiene formed in the initial [2+2] cycloaddition step is over-stabilized and the catalytic turnover brought to a halt. Guided by the 183 W NMR shifts as a proxy for the Lewis acidity of the central atom and by an accompanying chemical shift tensor analysis of the alkylidyne unit, the ligand design was revisited and a more strongly π-donating all-alkoxide ligand prepared. The new expanded chelate complex has a tempered Lewis acidity and outperforms the classical Schrock catalyst, carrying monodentate tert-butoxy ligands, in terms of rate and functional-group compatibility.
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Affiliation(s)
| | - Markus Leutzsch
- Max-Planck-Institut für Kohlenforschung45470Mülheim/RuhrGermany
| | - Christopher P. Gordon
- Department of Chemistry and Applied BiosciencesETH ZürichVladimir-Prelog-Weg 1–58093ZürichSwitzerland
| | - Christophe Copéret
- Department of Chemistry and Applied BiosciencesETH ZürichVladimir-Prelog-Weg 1–58093ZürichSwitzerland
| | - Alois Fürstner
- Max-Planck-Institut für Kohlenforschung45470Mülheim/RuhrGermany
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20
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Kashihara M, Gordon CP, Copéret C. Reactivity of Substituted Benzenes toward Oxidative Addition Relates to NMR Chemical Shift of the Ipso-Carbon. Org Lett 2020; 22:8910-8915. [PMID: 33147975 DOI: 10.1021/acs.orglett.0c03300] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The oxidative addition of benzene derivatives to Pd0 catalysts is a key step in cross-coupling reactions. In this work, we show that the ipso-carbon chemical shift of substituted benzenes, and in particular the δ22 component of the chemical shift tensor, correlates with the free energy barrier for oxidative addition. This correlation is traced back to the electron density in the pz orbital of the ipso-carbon (perpendicular of the ring-plane), with high electron densities favoring oxidative addition. The correlation between chemical shift and free energy barrier holds true for a variety of substituted benzenes, making chemical shift a useful descriptor for predicting the reactivity of aromatic substrates in oxidative addition.
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Affiliation(s)
- Myuto Kashihara
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan.,Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir Prelog Weg 1-5, 8093, Zürich, Switzerland
| | - Christopher P Gordon
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir Prelog Weg 1-5, 8093, Zürich, Switzerland
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir Prelog Weg 1-5, 8093, Zürich, Switzerland
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21
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Gordon CP, Engler H, Tragl AS, Plodinec M, Lunkenbein T, Berkessel A, Teles JH, Parvulescu AN, Copéret C. Efficient epoxidation over dinuclear sites in titanium silicalite-1. Nature 2020; 586:708-713. [PMID: 33116285 DOI: 10.1038/s41586-020-2826-3] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 08/26/2020] [Indexed: 11/09/2022]
Abstract
Titanium silicalite-1 (TS-1) is a zeolitic material with MFI framework structure, in which 1 to 2 per cent of the silicon atoms are substituted for titanium atoms. It is widely used in industry owing to its ability to catalytically epoxidize olefins with hydrogen peroxide (H2O2), leaving only water as a byproduct1,2; around one million tonnes of propylene oxide are produced each year using this process3. The catalytic properties of TS-1 are generally attributed to the presence of isolated Ti(IV) sites within the zeolite framework1. However, despite almost 40 years of experimental and computational investigation4-10, the structure of these active Ti(IV) sites is unconfirmed, owing to the challenges of fully characterizing TS-1. Here, using a combination of spectroscopy and microscopy, we characterize in detail a series of highly active and selective TS-1 propylene epoxidation catalysts with well dispersed titanium atoms. We find that, on contact with H217O2, all samples exhibit a characteristic solid-state 17O nuclear magnetic resonance signature that is indicative of the formation of bridging peroxo species on dinuclear titanium sites. Further, density functional theory calculations indicate that cooperativity between two titanium atoms enables propylene epoxidation via a low-energy reaction pathway with a key oxygen-transfer transition state similar to that of olefin epoxidation by peracids. We therefore propose that dinuclear titanium sites, rather than isolated titanium atoms in the framework, explain the high efficiency of TS-1 in propylene epoxidation with H2O2. This revised view of the active-site structure may enable further optimization of TS-1 and the industrial epoxidation process.
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Affiliation(s)
- Christopher P Gordon
- Department of Chemistry and Applied Biosciences, ETH Zürich, Zurich, Switzerland
| | - Hauke Engler
- Department of Chemistry, Cologne University, Cologne, Germany
| | - Amadeus Samuel Tragl
- Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society, Berlin, Germany
| | - Milivoj Plodinec
- Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society, Berlin, Germany
| | - Thomas Lunkenbein
- Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society, Berlin, Germany
| | | | | | | | - Christophe Copéret
- Department of Chemistry and Applied Biosciences, ETH Zürich, Zurich, Switzerland.
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22
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Venkatesh A, Lund A, Rochlitz L, Jabbour R, Gordon CP, Menzildjian G, Viger-Gravel J, Berruyer P, Gajan D, Copéret C, Lesage A, Rossini AJ. The Structure of Molecular and Surface Platinum Sites Determined by DNP-SENS and Fast MAS 195Pt Solid-State NMR Spectroscopy. J Am Chem Soc 2020; 142:18936-18945. [DOI: 10.1021/jacs.0c09101] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Amrit Venkatesh
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
- US DOE Ames Laboratory, Ames, Iowa 50011, United States
| | - Alicia Lund
- Univ Lyon, ENS Lyon, Université Lyon 1, CNRS, High-Field NMR Center of Lyon, FRE 2034, F-69100 Villeurbanne, France
| | - Lukas Rochlitz
- Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Ribal Jabbour
- Univ Lyon, ENS Lyon, Université Lyon 1, CNRS, High-Field NMR Center of Lyon, FRE 2034, F-69100 Villeurbanne, France
| | - Christopher P. Gordon
- Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Georges Menzildjian
- Univ Lyon, ENS Lyon, Université Lyon 1, CNRS, High-Field NMR Center of Lyon, FRE 2034, F-69100 Villeurbanne, France
| | - Jasmine Viger-Gravel
- Univ Lyon, ENS Lyon, Université Lyon 1, CNRS, High-Field NMR Center of Lyon, FRE 2034, F-69100 Villeurbanne, France
- Department of Organic Chemistry, University of Geneva, 1211 Geneva, Switzerland
| | - Pierrick Berruyer
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - David Gajan
- Univ Lyon, ENS Lyon, Université Lyon 1, CNRS, High-Field NMR Center of Lyon, FRE 2034, F-69100 Villeurbanne, France
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Anne Lesage
- Univ Lyon, ENS Lyon, Université Lyon 1, CNRS, High-Field NMR Center of Lyon, FRE 2034, F-69100 Villeurbanne, France
| | - Aaron J. Rossini
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
- US DOE Ames Laboratory, Ames, Iowa 50011, United States
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23
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Hillenbrand J, Leutzsch M, Gordon CP, Copéret C, Fürstner A. 183
W NMR Spectroscopy Guides the Search for Tungsten Alkylidyne Catalysts for Alkyne Metathesis. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202009975] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
| | - Markus Leutzsch
- Max-Planck-Institut für Kohlenforschung 45470 Mülheim/Ruhr Germany
| | - Christopher P. Gordon
- Department of Chemistry and Applied Biosciences ETH Zürich Vladimir-Prelog-Weg 1–5 8093 Zürich Switzerland
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences ETH Zürich Vladimir-Prelog-Weg 1–5 8093 Zürich Switzerland
| | - Alois Fürstner
- Max-Planck-Institut für Kohlenforschung 45470 Mülheim/Ruhr Germany
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24
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Moroz IB, Florian P, Viger‐Gravel J, Gordon CP, Lesage A, Copéret C. Silica‐Grafted Tris(neopentyl)aluminum: A Monomeric Aluminum Solid Co‐catalyst for Efficient Nickel‐Catalyzed Ethene Dimerization. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202006285] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Ilia B. Moroz
- Department of Chemistry and Applied Biosciences ETH Zürich Vladimir-Prelog-Weg 1–5 8093 Zürich Switzerland
| | - Pierre Florian
- CEMHTI CNRS UPR3079 Université d'Orléans 1D Avenue de la Recherche-Scientifique 45071 Orléans Cedex 2 France
| | - Jasmine Viger‐Gravel
- Centre de RMN à Très Hauts Champs Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1) 69100 Villeurbanne France
| | - Christopher P. Gordon
- Department of Chemistry and Applied Biosciences ETH Zürich Vladimir-Prelog-Weg 1–5 8093 Zürich Switzerland
| | - Anne Lesage
- Centre de RMN à Très Hauts Champs Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1) 69100 Villeurbanne France
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences ETH Zürich Vladimir-Prelog-Weg 1–5 8093 Zürich Switzerland
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25
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Moroz IB, Florian P, Viger-Gravel J, Gordon CP, Lesage A, Copéret C. Silica-Grafted Tris(neopentyl)aluminum: A Monomeric Aluminum Solid Co-catalyst for Efficient Nickel-Catalyzed Ethene Dimerization. Angew Chem Int Ed Engl 2020; 59:16167-16172. [PMID: 32452148 DOI: 10.1002/anie.202006285] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 05/21/2020] [Indexed: 11/11/2022]
Abstract
A silica-supported monomeric alkylaluminum co-catalyst was prepared via surface organometallic chemistry by contacting tris(neopentyl)aluminum and partially dehydroxylated silica. This system, fully characterized by solid-state 27 Al NMR spectroscopy augmented by computational studies, efficiently activates (n Bu3 P)2 NiCl2 towards dimerization of ethene, demonstrating comparable activity to previously reported dimeric diethylaluminum chloride supported on silica. Three types of aluminum surface species have been identified: monografted tetracoordinated Al species as well as two types of bisgrafted Al species-tetra- and pentacoordinated. Of them, only the monografted Al species is proposed to be able to activate the (n Bu3 P)2 NiCl2 complex and generate the active cationic species.
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Affiliation(s)
- Ilia B Moroz
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1-5, 8093, Zürich, Switzerland
| | - Pierre Florian
- CEMHTI CNRS UPR3079, Université d'Orléans, 1D Avenue de la Recherche-Scientifique, 45071, Orléans Cedex 2, France
| | - Jasmine Viger-Gravel
- Centre de RMN à Très Hauts Champs, Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1), 69100, Villeurbanne, France
| | - Christopher P Gordon
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1-5, 8093, Zürich, Switzerland
| | - Anne Lesage
- Centre de RMN à Très Hauts Champs, Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1), 69100, Villeurbanne, France
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1-5, 8093, Zürich, Switzerland
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26
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Hillenbrand J, Leutzsch M, Yiannakas E, Gordon CP, Wille C, Nöthling N, Copéret C, Fürstner A. "Canopy Catalysts" for Alkyne Metathesis: Molybdenum Alkylidyne Complexes with a Tripodal Ligand Framework. J Am Chem Soc 2020; 142:11279-11294. [PMID: 32463684 PMCID: PMC7322728 DOI: 10.1021/jacs.0c04742] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
![]()
A new family of structurally well-defined
molybdenum alkylidyne
catalysts for alkyne metathesis, which is distinguished by a tripodal
trisilanolate ligand architecture, is presented. Complexes of type 1 combine the virtues of previous generations of silanolate-based
catalysts with a significantly improved functional group tolerance.
They are easy to prepare on scale; the modularity of the ligand synthesis
allows the steric and electronic properties to be fine-tuned and hence
the application profile of the catalysts to be optimized. This opportunity
is manifested in the development of catalyst 1f, which
is as reactive as the best ancestors but exhibits an unrivaled scope.
The new catalysts work well in the presence of unprotected alcohols
and various other protic groups. The chelate effect entails even a
certain stability toward water, which marks a big leap forward in
metal alkylidyne chemistry in general. At the same time, they tolerate
many donor sites, including basic nitrogen and numerous heterocycles.
This aspect is substantiated by applications to polyfunctional (natural)
products. A combined spectroscopic, crystallographic, and computational
study provides insights into structure and electronic character of
complexes of type 1. Particularly informative are a density
functional theory (DFT)-based chemical shift tensor analysis of the
alkylidyne carbon atom and 95Mo NMR spectroscopy; this
analytical tool had been rarely used in organometallic chemistry before
but turns out to be a sensitive probe that deserves more attention.
The data show that the podand ligands render a Mo-alkylidyne a priori
more electrophilic than analogous monodentate triarylsilanols; proper
ligand tuning, however, allows the Lewis acidity as well as the steric
demand about the central atom to be adjusted to the point that excellent
performance of the catalyst is ensured.
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Affiliation(s)
| | - Markus Leutzsch
- Max-Planck-Institut für Kohlenforschung, 45470 Mülheim/Ruhr, Germany
| | - Ektoras Yiannakas
- Max-Planck-Institut für Kohlenforschung, 45470 Mülheim/Ruhr, Germany
| | - Christopher P Gordon
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1-5, 8093 Zürich, Switzerland
| | - Christian Wille
- Max-Planck-Institut für Kohlenforschung, 45470 Mülheim/Ruhr, Germany
| | - Nils Nöthling
- Max-Planck-Institut für Kohlenforschung, 45470 Mülheim/Ruhr, Germany
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1-5, 8093 Zürich, Switzerland
| | - Alois Fürstner
- Max-Planck-Institut für Kohlenforschung, 45470 Mülheim/Ruhr, Germany
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27
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Piveteau L, Dirin DN, Gordon CP, Walder BJ, Ong TC, Emsley L, Copéret C, Kovalenko MV. Colloidal-ALD-Grown Core/Shell CdSe/CdS Nanoplatelets as Seen by DNP Enhanced PASS-PIETA NMR Spectroscopy. Nano Lett 2020; 20:3003-3018. [PMID: 32078332 PMCID: PMC7227022 DOI: 10.1021/acs.nanolett.9b04870] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Ligand exchange and CdS shell growth onto colloidal CdSe nanoplatelets (NPLs) using colloidal atomic layer deposition (c-ALD) were investigated by solid-state nuclear magnetic resonance (NMR) experiments, in particular, dynamic nuclear polarization (DNP) enhanced phase adjusted spinning sidebands-phase incremented echo-train acquisition (PASS-PIETA). The improved sensitivity and resolution of DNP enhanced PASS-PIETA permits the identification and study of the core, shell, and surface species of CdSe and CdSe/CdS core/shell NPLs heterostructures at all stages of c-ALD. The cadmium chemical shielding was found to be proportionally dependent on the number and nature of coordinating chalcogen-based ligands. DFT calculations permitted the separation of the the 111/113Cd chemical shielding into its different components, revealing that the varying strength of paramagnetic and spin-orbit shielding contributions are responsible for the chemical shielding trend of cadmium chalcogenides. Overall, this study points to the roughening and increased chemical disorder at the surface during the shell growth process, which is not readily captured by the conventional characterization tools such as electron microscopy.
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Affiliation(s)
- Laura Piveteau
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, Zurich CH-8093, Switzerland
- Empa-Swiss
Federal Laboratories for Materials Science and Technology, Dübendorf, Überlandstrasse
129, Zurich CH-8600, Switzerland
| | - Dmitry N. Dirin
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, Zurich CH-8093, Switzerland
- Empa-Swiss
Federal Laboratories for Materials Science and Technology, Dübendorf, Überlandstrasse
129, Zurich CH-8600, Switzerland
| | - Christopher P. Gordon
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, Zurich CH-8093, Switzerland
| | - Brennan J. Walder
- Institut
des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Ta-Chung Ong
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, Zurich CH-8093, Switzerland
| | - Lyndon Emsley
- Institut
des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Christophe Copéret
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, Zurich CH-8093, Switzerland
- E-mail:
| | - Maksym V. Kovalenko
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, Zurich CH-8093, Switzerland
- Empa-Swiss
Federal Laboratories for Materials Science and Technology, Dübendorf, Überlandstrasse
129, Zurich CH-8600, Switzerland
- E-mail:
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28
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Dankers C, Tadros J, Harman DG, Aldrich-Wright JR, Nguyen TV, Gordon CP. Immobilized Carbodiimide Assisted Flow Combinatorial Protocol to Facilitate Amide Coupling and Lactamization. ACS Comb Sci 2020; 22:255-267. [PMID: 32283009 DOI: 10.1021/acscombsci.0c00001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Through a screen of over one hundred and 30 permutations of reaction temperatures, solvents, carbodiimide resins, and carbodiimide molar equivalences, in the presence, absence, or combination of diisopropylamine and benzotriazole additives, a convenient and first reported carbodiimide polymer-assisted flow approach to effect amide coupling and lactamization was developed. The protocol entails injecting a single solution (1:9 dimethylformamide: dichloromethane) containing a carboxylic acid and an amine or linear peptide sequence into a continuous stream of dichloromethane. The protocol remained viable in the absence of base, did not require carboxylate preactivation which, and in concert with minimal workup requirements, enabled the isolation of products in high yields. Compared to the utilization of untethered carbodiimide reagents, the flow procedure was also observed to provide a degree of racemization safety.
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Affiliation(s)
- Christian Dankers
- School of Science, Western Sydney University, Locked Bag, Penrith South DC, Sydney, New South Wales 1797, Australia
| | - Joseph Tadros
- School of Science, Western Sydney University, Locked Bag, Penrith South DC, Sydney, New South Wales 1797, Australia
| | - David G. Harman
- School of Medicine, Western Sydney University, Building 30, Goldsmith Avenue, Campbelltown, New South Wales 2560, Australia
- Molecular Medicine Research Group, School of Medicine, Western Sydney University, Building 30, Goldsmith Avenue, Campbelltown, New South Wales 2560, Australia
| | - Janice R. Aldrich-Wright
- School of Science, Western Sydney University, Locked Bag, Penrith South DC, Sydney, New South Wales 1797, Australia
- Nanoscale Organization and Dynamics Group, Western Sydney University, Campbelltown, New South Wales 2560, Australia
| | - Thanh V. Nguyen
- School of Chemistry, University of New South Wales, Sydney New South Wales 2052, Australia
| | - Christopher P. Gordon
- School of Science, Western Sydney University, Locked Bag, Penrith South DC, Sydney, New South Wales 1797, Australia
- Molecular Medicine Research Group, School of Medicine, Western Sydney University, Building 30, Goldsmith Avenue, Campbelltown, New South Wales 2560, Australia
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29
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Abstract
The accessory gene regulator (agr) quorum-sensing system is arguably the most important regulator of staphylococcus virulence and has been the focus of tremendous interest in the development of effective therapies for pathogenic bacterial infections. With regards to chemotherapeutic based strategies, the significant proportion of currently reported agr-system modulating molecules are mimics of the native ArgC substrate, which is a thioester-based macrocyclic peptide know as the auto-inducing peptide. Over the past two decades, more than two-hundred synthetic analogues have been reported. This review traces the development of the synthetic strategies employed to synthesise these analogues with a particular focus on macrocyclisation. At present these synthetic approaches can be clustered into five broad categories (1) solution-phase cyclisation, (2) immobilised carbodiimide assisted cyclisation, (3) concomitant on-resin cleavage and macrocyclisation, (4) Boc-compatible chemoselective thioesterification, and (5) Fmoc-compatible chemoselective thioesterification. The advantages and limitation provided by each of the approaches are compared and contrasted with a view towards potential reaction scale-up.
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Affiliation(s)
- Christopher P Gordon
- School of Science and Health, Western Sydney University, Locked Bag 1797, Penrith South DC, NSW 2751, Australia.
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30
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Beaumier EP, Gordon CP, Harkins RP, McGreal ME, Wen X, Copéret C, Goodpaster JD, Tonks IA. Cp 2Ti(κ 2-tBuNCN tBu): A Complex with an Unusual κ 2 Coordination Mode of a Heterocumulene Featuring a Free Carbene. J Am Chem Soc 2020; 142:8006-8018. [PMID: 32240590 PMCID: PMC7201867 DOI: 10.1021/jacs.0c02487] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Although there are myriad binding modes of heterocumulenes to metal centers, the monometallic κ2-ECE (E = O, S, NR) coordination mode has not been reported. Herein, the synthesis, isolation, and physical characterization of Cp2Ti(κ2-tBuNCNtBu) (3) (Cp = cyclopentadienyl, tBu = tert-butyl), a strained 4-membered metallacycle bearing a free carbene, is described. Computational (DFT, CASSCF, QT-AIM, ELF) and solid-state CP-MAS 13C NMR spectroscopic analysis indicate that 3 is best described as a free carbene with partial Ti-Cβ bonding that results from Ti-N π-bonding mixing with N-C-N σ-bonding of the bent N-C-N framework. Reactivity studies of 3 corroborate its carbene-like nature: protonation with [LutH]I results in the formation of a Ti-formamidinate (4), while oxidation with S8 yields a Ti-thioureate (5). Additionally, a related bridged dititanamidocarbene, (Cp2Ti)2(μ-η1,η1-CyNCNCy) (10) (Cy = cyclohexyl) is reported. Taken together, this work suggests that the 2-electron reduction of heterocumulene moieties can allow access to unusual free carbene coordination geometries given the proper stabilizing coordination environment from the reducing transition metal fragment.
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Affiliation(s)
- Evan P. Beaumier
- Department of Chemistry, University of Minnesota – Twin Cities, 207 Pleasant St SE, Minneapolis MN 55455
| | - Christopher P. Gordon
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1-5, 8093 Zürich, Switzerland
| | - Robin P. Harkins
- Department of Chemistry, University of Minnesota – Twin Cities, 207 Pleasant St SE, Minneapolis MN 55455
| | - Meghan E. McGreal
- Department of Chemistry, University of Minnesota – Twin Cities, 207 Pleasant St SE, Minneapolis MN 55455
| | - Xuelan Wen
- Department of Chemistry, University of Minnesota – Twin Cities, 207 Pleasant St SE, Minneapolis MN 55455
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1-5, 8093 Zürich, Switzerland
| | - Jason D. Goodpaster
- Department of Chemistry, University of Minnesota – Twin Cities, 207 Pleasant St SE, Minneapolis MN 55455
| | - Ian A. Tonks
- Department of Chemistry, University of Minnesota – Twin Cities, 207 Pleasant St SE, Minneapolis MN 55455
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31
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Abstract
Spectator oxo ligands are ubiquitous in catalysis, in particular in olefin epoxidation and olefin metathesis. Here we use computationally derived 17O NMR parameters to probe the electronic structure of spectator oxo ligands in these two reactions. We show that 17O NMR parameters allow to distinguish between doubly-bonded and triply-bonded oxo ligands, giving detailed insights into the frontier molecular orbitals involved in the metaloxo bonds along the reaction pathway. On the one hand, our study shows that in olefin epoxidation catalysed by methyltrioxorhenium (MTO), the oxo ligand significantly changes its bonding mode upon formation of the oxygen-transferring Re-oxo-bisperoxo-species, changing its nature from a doubly bonded to a triply bonded oxo ligand. On the other hand, only minor changes in the binding mode are found along the olefin metathesis reaction pathway with Mo- and W-based oxo-alkylidene species, in which the oxo ligand behaves as a triply bonded ligand throughout the reaction. This finding contrasts earlier studies that proposed that the change of binding mode of the oxo ligand was key to metallacyclobutane formation.
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Affiliation(s)
- Christopher P Gordon
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1-5, CH-8093 Zurich, Switzerland
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1-5, CH-8093 Zurich, Switzerland;,
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32
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Gordon CP, Copéret C. Metal Alkyls with Alkylidynic Metal-Carbon Bond Character: Key Electronic Structures in Alkane Metathesis Precatalysts. Angew Chem Int Ed Engl 2020; 59:7035-7041. [PMID: 32026552 DOI: 10.1002/anie.201915557] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 01/09/2020] [Indexed: 11/07/2022]
Abstract
The homologation of alkanes via alkane metathesis is catalyzed at low temperatures (150 °C) by the silica-supported species (≡SiO)WMe5 and (≡SiO)TaMe4 , while (≡SiO)TaMe3 Cp* is inactive. The contrasting reactivity is paralleled by differences in the 13 C NMR signature; the former display significantly more deshielded isotropic chemical shifts (δiso ) and almost axially symmetric chemical shift tensors, similar to what is observed in their molecular precursors TaMe5 and WMe6 . Analysis of the chemical shift tensors reveals the presence of a triple-bond character in their metal-carbon (formally single) bond. This electronic structure is reflected in their propensity to generate alkylidynes and to participate in alkane metathesis, further supporting the role of alkylidynes as key reaction intermediates. This study establishes chemical shift as a descriptor to identify potential alkane metathesis catalysts.
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Affiliation(s)
- Christopher P Gordon
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1-5, 8093, Zürich, Switzerland
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 1-5, 8093, Zürich, Switzerland
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33
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Gordon CP, Copéret C. Metal Alkyls with Alkylidynic Metal‐Carbon Bond Character: Key Electronic Structures in Alkane Metathesis Precatalysts. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201915557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Christopher P. Gordon
- Department of Chemistry and Applied Biosciences ETH Zürich Vladimir-Prelog-Weg 1–5 8093 Zürich Switzerland
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences ETH Zürich Vladimir-Prelog-Weg 1–5 8093 Zürich Switzerland
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34
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Bumberger AE, Gordon CP, Trummer D, Copéret C. C−H Activation and Olefin Insertion in d
8
and d
0
Complexes: Same Elementary Steps, Different Electronics. Helv Chim Acta 2020. [DOI: 10.1002/hlca.201900278] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Andreas E. Bumberger
- Department of Chemistry and Applied BiosciencesETH Zürich Vladimir Prelog Weg 1–5 CH-8093 Zürich Switzerland
| | - Christopher P. Gordon
- Department of Chemistry and Applied BiosciencesETH Zürich Vladimir Prelog Weg 1–5 CH-8093 Zürich Switzerland
| | - David Trummer
- Department of Chemistry and Applied BiosciencesETH Zürich Vladimir Prelog Weg 1–5 CH-8093 Zürich Switzerland
| | - Christophe Copéret
- Department of Chemistry and Applied BiosciencesETH Zürich Vladimir Prelog Weg 1–5 CH-8093 Zürich Switzerland
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35
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Pietrasiak E, Gordon CP, Copéret C, Togni A. Understanding 125Te NMR chemical shifts in disymmetric organo-telluride compounds from natural chemical shift analysis. Phys Chem Chem Phys 2020; 22:2319-2326. [DOI: 10.1039/c9cp05934b] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Magnetic coupling of the lone pair: theoretical investigations reveal the origin of 125Te chemical shift in disymmetric organotellurides
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Affiliation(s)
- Ewa Pietrasiak
- ETH Zürich
- Department of Chemistry and Applied Sciences
- Vladimir-Prelog-Weg 2
- CH-8093 Zürich
- Switzerland
| | - Christopher P. Gordon
- ETH Zürich
- Department of Chemistry and Applied Sciences
- Vladimir-Prelog-Weg 2
- CH-8093 Zürich
- Switzerland
| | - Christophe Copéret
- ETH Zürich
- Department of Chemistry and Applied Sciences
- Vladimir-Prelog-Weg 2
- CH-8093 Zürich
- Switzerland
| | - Antonio Togni
- ETH Zürich
- Department of Chemistry and Applied Sciences
- Vladimir-Prelog-Weg 2
- CH-8093 Zürich
- Switzerland
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36
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Abstract
The accessory gene regulator (agr) quorum-sensing system is arguably the most important regulator of Staphylococcus virulence. The agr-system serves a crucial role in pathogenesis by triggering substantive gene expression alterations to up-regulate the production of a wide variety of virulence determinants such as exoenzymes (proteases, lipases, nucleases) and downregulate the expression of surface binding proteins. Accordingly, the agr-system represents a compelling target for the development of antivirulence therapeutics as potential adjuncts, or alternatives, to conventional bactericidal and bacteriostatic antibiotics. Despite this potential, to date, no agr-system inhibitors have progressed to the clinic; however, several promising lead compounds have been identified through screens of synthetic and natural product libraries. On the basis of the molecular components within the agr-system, the current contingent of regulating compounds can be clustered into three broad groups, AgrA-P3 activation inhibitors, AgrB-AgrD processing inhibitors, and AgrC-AIP interaction inhibitors. This review aims to provide an overview of the development, structure-activity-relationships, and limitations of compounds within each of these groups in addition to the current opportunities for developing next-generation anologs.
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Affiliation(s)
- Alexander R Horswill
- Veterans Affairs Eastern Colorado Health Care System, Aurora, Colorado 80045, United States.,Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, United States
| | - Christopher P Gordon
- School of Science and Health, Western Sydney University, Locked Bag 1797, Penrith South DC, NSW 2751, Australia.,Molecular Medicine Research Group, School of Medicine, Westerm Sydney University, Building 30, Campbelltown, NSW 2560, Australia
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37
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Zhizhko PA, Toth F, Gordon CP, Chan KW, Liao W, Mougel V, Copéret C. Molecular and Silica‐Supported Mo and W d
0
Imido‐Methoxybenzylidene Complexes: Structure and Metathesis Activity. Helv Chim Acta 2019. [DOI: 10.1002/hlca.201900190] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Pavel A. Zhizhko
- Department of Chemistry and Applied BiosciencesETH Zürich Vladimir Prelog Weg 1–5 CH-8093 Zürich Switzerland
- A. N. Nesmeyanov Institute of Organoelement CompoundsRussian Academy of Sciences Vavilov str. 28 RU-119991 Moscow Russia
| | - Florian Toth
- XiMo Hungary Zahony u. 7 HU-1031 Budapest Hungary
| | - Christopher P. Gordon
- Department of Chemistry and Applied BiosciencesETH Zürich Vladimir Prelog Weg 1–5 CH-8093 Zürich Switzerland
| | - Ka Wing Chan
- Department of Chemistry and Applied BiosciencesETH Zürich Vladimir Prelog Weg 1–5 CH-8093 Zürich Switzerland
| | - Wei‐Chih Liao
- Department of Chemistry and Applied BiosciencesETH Zürich Vladimir Prelog Weg 1–5 CH-8093 Zürich Switzerland
- Current address: Department of ChemistryUniversity of California Berkeley Berkeley California 94720 USA
| | - Victor Mougel
- Department of Chemistry and Applied BiosciencesETH Zürich Vladimir Prelog Weg 1–5 CH-8093 Zürich Switzerland
| | - Christophe Copéret
- Department of Chemistry and Applied BiosciencesETH Zürich Vladimir Prelog Weg 1–5 CH-8093 Zürich Switzerland
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38
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Gordon CP, Andersen RA, Copéret C. Metal Olefin Complexes: Revisiting the
Dewar
−
Chatt
−
Duncanson
Model and Deriving Reactivity Patterns from Carbon‐13 NMR Chemical Shift. Helv Chim Acta 2019. [DOI: 10.1002/hlca.201900151] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Christopher P. Gordon
- Department of Chemistry and Applied BiosciencesETH Zürich Vladimir-Prelog-Weg 1–5 CH-8093 Zürich Switzerland
| | - Richard A. Andersen
- Department of ChemistryUniversity of California Berkeley, California 94720 United States
| | - Christophe Copéret
- Department of Chemistry and Applied BiosciencesETH Zürich Vladimir-Prelog-Weg 1–5 CH-8093 Zürich Switzerland
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39
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Gordon CP, Raynaud C, Andersen RA, Copéret C, Eisenstein O. Carbon-13 NMR Chemical Shift: A Descriptor for Electronic Structure and Reactivity of Organometallic Compounds. Acc Chem Res 2019; 52:2278-2289. [PMID: 31339693 DOI: 10.1021/acs.accounts.9b00225] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Metal-bonded carbon atoms in metal-alkyl, metal-carbene/alkylidene, and metal-carbyne/alkylidyne species often show significantly more deshielded isotropic chemical shifts than their organic counterparts (alkanes, alkenes, and alkynes). While isotropic chemical shift is universally used to characterize a chemical compound in solution, it is an average value of the three principal components of the chemical shift tensor (δ11 > δ22 > δ33). The tensor components, which are accessible by solid-state NMR spectroscopy, can provide detailed information about the electronic structure (frontier molecular orbitals) at the observed nuclei. This information can be accessed in detail by quantum chemical calculations, most notably by an analysis of the paramagnetic contribution to the NMR shielding tensor. The paramagnetic term mainly results from the coupling of occupied and empty molecular orbitals close in energy-the frontier molecular orbitals-under the effect of the external magnetic field (B0). In organometallic compounds, a large deshielding of the isotropic carbon-13 chemical shift of the metal-bonded carbon atom is commonly related to the coupling between the occupied σM-C orbital and low-lying vacant orbitals of πM═C* character. The deshielding at the α-carbon hence probes the extent of σM-C and πM═C* interactions. This molecular orbital view readily explains the strong deshielding and large anisotropy (evidenced by the span Ω = δ11 - δ33) observed in metal alkylidenes and alkylidynes (200 < δiso < 400 ppm). Fischer carbenes are generally more deshielded than Schrock or Grubbs alkylidenes due to their low-lying πM═C* orbital. Chemical shift hence shows their higher electrophilic character, connecting NMR spectroscopy to reactivity patterns. Similarly, the α-carbon of metal-alkyls display deshielded chemical shifts in specific coordination environments. This deshielding, which is often prominently pronounced for cationic species, indicates the presence of partial π-bond character in the metal-carbon bond, making these bonds topologically equivalent to alkylidene π-bonds. The π-character in metal-alkyl bonds favors (i) α-H abstraction processes in metal bis-alkyl compounds yielding metal alkylidenes, (ii) [2 + 2]-retrocyclization of metallacyclobutanes that participate in olefin metathesis, (iii) olefin insertion in cationic metal alkyls thus explaining polymerization activity trends and the importance of α-H agostic interactions, and (iv) C-H bond activation on metal-alkyls via σ-bond metathesis. The presence of π-character in the metal-carbon bonds involved in these processes rationalizes the parallel reactivity patterns of metal-alkyls toward olefin insertion and σ-bond metathesis and the fact that σ-bond metathesis, olefin insertion, and olefin metathesis are commonly observed with metal atoms in the same ligand field. Because of the similarities in the frontier molecular orbitals involved in these processes, these reactions can be viewed as isolobal. This explains why certain fragments, such as bent metallocenes (d0 Cp2M) or T-shaped L3M, are ubiquitous in these reactions.
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Affiliation(s)
- Christopher P. Gordon
- ETH Zürich, Department of Chemistry and Applied Biosciences, Vladimir Prelog Weg. 1-5, CH-8093 Zürich, Switzerland
| | | | - Richard A. Andersen
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Christophe Copéret
- ETH Zürich, Department of Chemistry and Applied Biosciences, Vladimir Prelog Weg. 1-5, CH-8093 Zürich, Switzerland
| | - Odile Eisenstein
- ICGM, Université Montpellier, CNRS, ENSCM, 34095 Montpellier, France
- Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Oslo, P.O.
Box 1033, Blindern, 0315 Oslo, Norway
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40
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Pucino M, Zhai F, Gordon CP, Mance D, Hoveyda AH, Schrock RR, Copéret C. Silica-Supported Molybdenum Oxo Alkylidenes: Bridging the Gap between Internal and Terminal Olefin Metathesis. Angew Chem Int Ed Engl 2019; 58:11816-11819. [PMID: 31099940 DOI: 10.1002/anie.201903325] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 05/15/2019] [Indexed: 11/11/2022]
Abstract
Grafting a molybdenum oxo alkylidene on silica (partially dehydroxylated at 700 °C) affords the first example of a well-defined silica-supported Mo oxo alkylidene, which is an analogue of the putative active sites in heterogeneous Mo-based metathesis catalysts. In contrast to its tungsten analogue, which shows poor activity towards terminal olefins because of the formation of a stable off-cycle metallacyclobutane intermediate, the Mo catalyst shows high metathesis activity for both terminal and internal olefins that is consistent with the lower stability of Mo metallacyclobutane intermediates. This Mo oxo metathesis catalyst also outperforms its corresponding neutral silica-supported Mo and W imido analogues.
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Affiliation(s)
- Margherita Pucino
- Department of Chemistry and Applied Bioscience, ETH Zürich, Vladimir Prelog Weg 2, 8093, Zürich, Switzerland
| | - Feng Zhai
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Christopher P Gordon
- Department of Chemistry and Applied Bioscience, ETH Zürich, Vladimir Prelog Weg 2, 8093, Zürich, Switzerland
| | - Deni Mance
- Department of Chemistry and Applied Bioscience, ETH Zürich, Vladimir Prelog Weg 2, 8093, Zürich, Switzerland
| | - Amir H Hoveyda
- Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA, 02467, USA.,Supramolecular Science and Engineering Institute, University of Strasbourg, CNRS, 67000, Strasbourg, France
| | - Richard R Schrock
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Christophe Copéret
- Department of Chemistry and Applied Bioscience, ETH Zürich, Vladimir Prelog Weg 2, 8093, Zürich, Switzerland
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41
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Pucino M, Zhai F, Gordon CP, Mance D, Hoveyda AH, Schrock RR, Copéret C. Silica‐Supported Molybdenum Oxo Alkylidenes: Bridging the Gap between Internal and Terminal Olefin Metathesis. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201903325] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Margherita Pucino
- Department of Chemistry and Applied Bioscience ETH Zürich Vladimir Prelog Weg 2 8093 Zürich Switzerland
| | - Feng Zhai
- Department of Chemistry Massachusetts Institute of Technology Cambridge MA 02139 USA
| | - Christopher P. Gordon
- Department of Chemistry and Applied Bioscience ETH Zürich Vladimir Prelog Weg 2 8093 Zürich Switzerland
| | - Deni Mance
- Department of Chemistry and Applied Bioscience ETH Zürich Vladimir Prelog Weg 2 8093 Zürich Switzerland
| | - Amir H. Hoveyda
- Department of Chemistry Merkert Chemistry Center Boston College Chestnut Hill MA 02467 USA
- Supramolecular Science and Engineering Institute University of Strasbourg, CNRS 67000 Strasbourg France
| | - Richard R. Schrock
- Department of Chemistry Massachusetts Institute of Technology Cambridge MA 02139 USA
| | - Christophe Copéret
- Department of Chemistry and Applied Bioscience ETH Zürich Vladimir Prelog Weg 2 8093 Zürich Switzerland
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42
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Pucino M, Allouche F, Gordon CP, Wӧrle M, Mougel V, Copéret C. A reactive coordinatively saturated Mo(iii) complex: exploiting the hemi-lability of tris( tert-butoxy)silanolate ligands. Chem Sci 2019; 10:6362-6367. [PMID: 31341592 PMCID: PMC6601292 DOI: 10.1039/c9sc01955c] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Accepted: 05/13/2019] [Indexed: 12/15/2022] Open
Abstract
Hemilabile tris(tert-butoxy)silanolate ligands allow stabilizing a mononuclear octahedral Mo(iii) complex without quenching its reactivity towards small molecules (N2, CO2, N2O).
Coordinatively unsaturated Mo(iii) complexes have been identified as highly reactive species able to activate dinitrogen without the need for a sacrificial reducing agent. Here, we report a coordinatively saturated octahedral Mo(iii) complex stabilized by κ2-tris(tert-butoxy)silanolate ligands, which is yet highly reactive towards dinitrogen and small molecules. The combined high stability and activity are ascribed to the dual binding mode of the tris(tert-butoxy)silanolate ligands that allow unlocking a coordination site in the presence of reactive small molecules to promote their activation at low temperatures.
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Affiliation(s)
- Margherita Pucino
- Department of Chemistry and Applied Biosciences , ETH Zurich , Vladimir-Prelog-Weg 2 , 8093 Zurich , Switzerland . ;
| | - Florian Allouche
- Department of Chemistry and Applied Biosciences , ETH Zurich , Vladimir-Prelog-Weg 2 , 8093 Zurich , Switzerland . ;
| | - Christopher P Gordon
- Department of Chemistry and Applied Biosciences , ETH Zurich , Vladimir-Prelog-Weg 2 , 8093 Zurich , Switzerland . ;
| | - Michael Wӧrle
- Department of Chemistry and Applied Biosciences , ETH Zurich , Vladimir-Prelog-Weg 2 , 8093 Zurich , Switzerland . ;
| | - Victor Mougel
- Department of Chemistry and Applied Biosciences , ETH Zurich , Vladimir-Prelog-Weg 2 , 8093 Zurich , Switzerland . ;
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences , ETH Zurich , Vladimir-Prelog-Weg 2 , 8093 Zurich , Switzerland . ;
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43
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Biberger T, Gordon CP, Leutzsch M, Peil S, Guthertz A, Copéret C, Fürstner A. Alkyne
gem
‐Hydrogenation: Formation of Pianostool Ruthenium Carbene Complexes and Analysis of Their Chemical Character. Angew Chem Int Ed Engl 2019; 58:8845-8850. [DOI: 10.1002/anie.201904255] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Indexed: 11/06/2022]
Affiliation(s)
- Tobias Biberger
- Max-Planck-Institut für Kohlenforschung 45470 Mülheim/Ruhr Germany
| | - Christopher P. Gordon
- Department of Chemistry and Applied BiosciencesETH Zürich Vladimir-Prelog-Weg 1–5 8093 Zürich Switzerland
| | - Markus Leutzsch
- Max-Planck-Institut für Kohlenforschung 45470 Mülheim/Ruhr Germany
| | - Sebastian Peil
- Max-Planck-Institut für Kohlenforschung 45470 Mülheim/Ruhr Germany
| | | | - Christophe Copéret
- Department of Chemistry and Applied BiosciencesETH Zürich Vladimir-Prelog-Weg 1–5 8093 Zürich Switzerland
| | - Alois Fürstner
- Max-Planck-Institut für Kohlenforschung 45470 Mülheim/Ruhr Germany
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44
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Biberger T, Gordon CP, Leutzsch M, Peil S, Guthertz A, Copéret C, Fürstner A. Alkyne
gem
‐Hydrogenation: Formation of Pianostool Ruthenium Carbene Complexes and Analysis of Their Chemical Character. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201904255] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Tobias Biberger
- Max-Planck-Institut für Kohlenforschung 45470 Mülheim/Ruhr Germany
| | - Christopher P. Gordon
- Department of Chemistry and Applied BiosciencesETH Zürich Vladimir-Prelog-Weg 1–5 8093 Zürich Switzerland
| | - Markus Leutzsch
- Max-Planck-Institut für Kohlenforschung 45470 Mülheim/Ruhr Germany
| | - Sebastian Peil
- Max-Planck-Institut für Kohlenforschung 45470 Mülheim/Ruhr Germany
| | | | - Christophe Copéret
- Department of Chemistry and Applied BiosciencesETH Zürich Vladimir-Prelog-Weg 1–5 8093 Zürich Switzerland
| | - Alois Fürstner
- Max-Planck-Institut für Kohlenforschung 45470 Mülheim/Ruhr Germany
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45
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Hizartzidis L, Gilbert J, Gordon CP, Sakoff JA, McCluskey A. Synthesis and Cytotoxicity of Octahydroepoxyisoindole‐7‐carboxylic Acids and Norcantharidin–Amide Hybrids as Norcantharidin Analogues. ChemMedChem 2019; 14:1152-1161. [DOI: 10.1002/cmdc.201900180] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Indexed: 01/17/2023]
Affiliation(s)
- Lacey Hizartzidis
- Chemistry, School of Environmental & Life Sciences The University of Newcastle 1 University Drive Callaghan NSW 2308 Australia
| | - Jayne Gilbert
- Experimental Therapeutics Group, Department of Medical Oncology Calvary Mater Hospital Edith Street Waratah NSW 2298 Australia
| | - Christopher P. Gordon
- Chemistry, School of Environmental & Life Sciences The University of Newcastle 1 University Drive Callaghan NSW 2308 Australia
- Present address: Department: School of Science and Health Western Sydney University Locked Bag 1797 Penrith South DC NSW 2750 Australia
| | - Jennette A. Sakoff
- Experimental Therapeutics Group, Department of Medical Oncology Calvary Mater Hospital Edith Street Waratah NSW 2298 Australia
| | - Adam McCluskey
- Chemistry, School of Environmental & Life Sciences The University of Newcastle 1 University Drive Callaghan NSW 2308 Australia
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46
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Affiliation(s)
- Christopher P. Gordon
- Department of Chemistry and Applied Biosciences, ETH Zürich Vladimir-Prelog-Weg 1-5, CH-8093 Zürich, Switzerland
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences, ETH Zürich Vladimir-Prelog-Weg 1-5, CH-8093 Zürich, Switzerland.
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47
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Abstract
Within a decade of Merrifield's seminal description of solid-phase peptide synthesis, the synergies between solid-phase approaches and flow synthesis were noted by a number of groups. However, despite the various advantages flow brings to peptide synthesis, throughout the 1990s and 2000s, interest in the technique was overshadowed by microwave assisted approaches. However, the current expansion of flow technologies has reinvigorated interest in both solid-phase and solution-phase continuous-flow approaches for assembling peptides. This perspective traces the introduction and evolution of continuous-flow solid-phase synthesis from a practical aspect with a particular focus on solid supports, acylation protocols, and racemisation suppression. Practical aspects of solution-phase continuous-flow peptide synthesis are also considered with an evaluation of microreactor systems, coupling protocols, and fragment-based approaches for assembly of extended peptide units.
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Affiliation(s)
- Christopher P Gordon
- School of Science and Health, Western Sydney University, Locked Bag, 1797, Penrith South, DC, Australia.
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48
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Gordon CP, Culver DB, Conley MP, Eisenstein O, Andersen RA, Copéret C. π-Bond Character in Metal-Alkyl Compounds for C-H Activation: How, When, and Why? J Am Chem Soc 2019; 141:648-656. [PMID: 30525557 DOI: 10.1021/jacs.8b11951] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
C-H bond activation via σ-bond metathesis is typically observed with transition-metal alkyl compounds in d0 or d0fn electron configurations, e.g., biscyclopentadienyl metal alkyls. Related C-H activation processes are also observed for transition-metal alkyls with higher d-electron counts, such as W(II), Fe(II), or Ir(III). A σ-bond metathesis mechanism has been proposed in all cases with a preference for an oxidative addition-reductive elimination pathway for Ir(III). Herein we show that, regardless of the exact mechanism, C-H activation with all of these compounds is associated with π-character of the M-C bond, according to a detailed analysis of the 13C NMR chemical shift tensor of the α-carbon. π-Character is also a requirement for olefin insertion, indicating its similarity to σ-bond metathesis. This observation explains the H2 response observed in d0 olefin polymerization catalysts and underlines that σ-bond metathesis, olefin insertion, and olefin metathesis are in fact isolobal reactions.
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Affiliation(s)
- Christopher P Gordon
- Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir Prelog Weg 1-5 , 8093 , Zürich , Switzerland
| | - Damien B Culver
- Department of Chemistry , University of California, Riverside , Riverside , California 92521 , United States
| | - Matthew P Conley
- Department of Chemistry , University of California, Riverside , Riverside , California 92521 , United States
| | - Odile Eisenstein
- Institut Charles Gerhardt, UMR 5253 CNRS-UM-ENSCM , Université de Montpellier , 34095 Montpellier , France.,Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry , University of Oslo , P.O. Box 1033, Blindern , 0315 Oslo , Norway
| | - Richard A Andersen
- Department of Chemistry , University of California , Berkeley , California 94720 , United States
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir Prelog Weg 1-5 , 8093 , Zürich , Switzerland
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49
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Spare LK, Menti M, Harman DG, Aldrich-Wright JR, Gordon CP. A continuous flow protocol to generate, regenerate, load, and recycle chlorotrityl functionalised resins. REACT CHEM ENG 2019. [DOI: 10.1039/c8re00318a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
From a screen of chlorinating agent concentration, flow rates, and reagent addition methodologies, a continuous flow protocol to activate, reactivate, and recycle both 2-chlorotrityl chloride functionalised polystyrene and trityl-hydroxy ChemMatrix functionalised resins was established.
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Affiliation(s)
- Lawson K. Spare
- School of Science and Health
- Western Sydney University
- Penrith South DC
- Australia
| | - Maria Menti
- School of Science and Health
- Western Sydney University
- Penrith South DC
- Australia
| | - David G. Harman
- School of Medicine
- Western Sydney University, Campbelltown Campus
- Australia
- Molecular Medicine Research Group
- Western Sydney University, Campbelltown Campus
| | - Janice R. Aldrich-Wright
- School of Science and Health
- Western Sydney University
- Penrith South DC
- Australia
- Nanoscale Organisation and Dynamics Group
| | - Christopher P. Gordon
- School of Science and Health
- Western Sydney University
- Penrith South DC
- Australia
- Molecular Medicine Research Group
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50
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Pucino M, Inoue M, Gordon CP, Schowner R, Stöhr L, Sen S, Hegedüs C, Robé E, Tóth F, Buchmeiser MR, Copéret C. Berichtigung: Promoting Terminal Olefin Metathesis with a Supported Cationic Molybdenum Imido Alkylidene N‐Heterocyclic Carbene Catalyst. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201812451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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