1
|
Weindl C, Hintermann L. Synthesis of Indolines via Base-Mediated C-H Activation and Defluorinative C-N Coupling, with no Need for Transition-Metals. Chemistry 2024:e202401034. [PMID: 38693605 DOI: 10.1002/chem.202401034] [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: 03/13/2024] [Revised: 04/20/2024] [Accepted: 04/28/2024] [Indexed: 05/03/2024]
Abstract
Syntheses of (partially) aromatic nitrogen heterocycles increasingly rely on transition-metal catalyzed C-C- and C-N-cross-coupling reactions. Here we describe a different approach to the synthesis of indolines by a domino C(sp3)-H activation, 1,2-addition, and defluorinative SNAr-cyclization sequence to provide the target 1,2-diarylindolines (1,2-diaryl-2,3-dihydroindoles) from ortho-fluorinated methyl-arenes and N-aryl imines (benzylidene anilines) in a cyclocondensation that is mediated by potassium hexa-methyl-di-silazide (KHMDS) as base exclusively. This transition-metal-free process via C-H and C-F bond activation provides a one-step entry into a wide array of indoline scaffolds (43 examples, up to 96% yield). This privileged substructure is common in natural products and pharmaceuticals alike, and cannot be accessed by traditional condensation reactions.
Collapse
Affiliation(s)
- Christian Weindl
- Technische Universität München, School of Natural Science, Department Chemie, Lichtenbergstr. 4, 85748, Garching bei München, GERMANY
| | - Lukas Hintermann
- Technische Universität München, School of Natural Sciences, Department Chemie, Lichtenbergstr. 4, 85748, Garching bei München, GERMANY
| |
Collapse
|
2
|
Wei MG, Li HR, He LN. Synthesis of Dimethyl Carbonate via Transesterification of Ethylene Carbonate and Methanol over Mesoporous KF-loaded Mg-Fe Oxides. Chempluschem 2024:e202300778. [PMID: 38441412 DOI: 10.1002/cplu.202300778] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2023] [Revised: 02/28/2024] [Indexed: 03/20/2024]
Abstract
A series of KF/Mg-Fe oxides were fabricated via the solid-state reaction between KF and Mg-Fe oxides. Especially, when 20 wt % KF was supported on the Mg-Fe bi-metal oxides and calcined at 400-600 °C, the solid material with more basic sites than the support itself was obtained. When applied as catalyst to dimethyl carbonate (DMC) synthesis through transesterification of ethylene carbonate (EC) and methanol, this material can afforded up to 88 % yield and 97 % selectivity toward DMC in 2 h under reflux conditions with the molar ratio of methanol to ethylene carbonate set at 8. It is worth noting that the catalyst was easily separated and reused, retaining at least 89 % catalytic activity during the first four recycles. Although an attenuated activity was still observed due to the inevitable filtration loss and dissolution, this solid base can still provide clues to the development recyclable catalyst in green synthesis of DMC.
Collapse
Affiliation(s)
- Meng-Ge Wei
- College of Pharmacy, Nankai University, 38 Tongyan Road, Tianjin, 300350, P. R. China
| | - Hong-Ru Li
- College of Pharmacy, Nankai University, 38 Tongyan Road, Tianjin, 300350, P. R. China
| | - Liang-Nian He
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, P. R. China
| |
Collapse
|
3
|
Kang B, Ikeda K. 4-Dimethylaminopyridine (DMAP), A Superior Mediator for Morita-Balylis-Hillman Reaction-Triggered Annulative Condensation of Salicylaldehydes and Acrylonitrile to Form 3-Cyano-2H-chromenes. Chem Pharm Bull (Tokyo) 2023; 71:318-325. [PMID: 36805528 DOI: 10.1248/cpb.c23-00068] [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] [Indexed: 02/18/2023]
Abstract
We unveiled superior base mediators for the annulative condensation of salicylaldehydes and acrylonitrile to give 3-cyano-2H-chromenes, which has been mediated only by 1,4-diazabicyclo[2.2.2]octane (DABCO) over the past two decades. The reactions were most efficiently mediated by 4-dimethylaminopyridine (DMAP), which yielded 3-cyano-2H-chromenes in higher yields than DABCO in most cases. We also confirmed that the reaction remained high yielding in a decagram-scale experiment with a catalytic amount of DMAP. The utility of this reaction was also exemplified by derivatization of an obtained 3-cyano-2H-chromene into a known 2H-chromene-3-carboxylic acid, which was previously synthesized with a non-readily available reagent.
Collapse
Affiliation(s)
- Bubwoong Kang
- Graduate School of Agricultural Science, Kobe University
| | - Kaede Ikeda
- Graduate School of Agricultural Science, Kobe University
| |
Collapse
|
4
|
Yu S, Tiekink EH, Vermeeren P, Bickelhaupt FM, Hamlin TA. How Bases Catalyze Diels-Alder Reactions. Chemistry 2023; 29:e202203121. [PMID: 36330879 PMCID: PMC10108159 DOI: 10.1002/chem.202203121] [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: 10/06/2022] [Revised: 11/03/2022] [Accepted: 11/04/2022] [Indexed: 11/06/2022]
Abstract
We have quantum chemically studied the base-catalyzed Diels-Alder (DA) reaction between 3-hydroxy-2-pyrone and N-methylmaleimide using dispersion-corrected density functional theory. The uncatalyzed reaction is slow and is preceded by the extrusion of CO2 via a retro-DA reaction. Base catalysis, for example, by triethylamine, lowers the reaction barrier up to 10 kcal mol-1 , causing the reaction to proceed smoothly at low temperature, which quenches the expulsion of CO2 , yielding efficient access to polyoxygenated natural compounds. Our activation strain analyses reveal that the base accelerates the DA reaction via two distinct electronic mechanisms: i) by the HOMO-raising effect, which enhances the normal electron demand orbital interaction; and ii) by donating charge into 3-hydroxy-2-pyrone which accumulates in its reactive region and promotes strongly stabilizing secondary electrostatic interactions with N-methylmaleimide.
Collapse
Affiliation(s)
- Song Yu
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM) Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam, (TheNetherlands
| | - Eveline H Tiekink
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM) Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam, (TheNetherlands
| | - Pascal Vermeeren
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM) Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam, (TheNetherlands
| | - F Matthias Bickelhaupt
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM) Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam, (TheNetherlands.,Institute for Molecules and Materials (IMM), Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen (The, Netherlands.,Department of Chemical Sciences, University of Johannesburg, Auckland Park, Johannesburg, 2006, South Africa
| | - Trevor A Hamlin
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM) Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam, (TheNetherlands
| |
Collapse
|
5
|
Harada N, Asano T, Sugiura M, Kotani S, Nakajima M. Lithium Binaphtholate-Catalyzed Asymmetric Michael Reaction of Acrylamides. Chem Pharm Bull (Tokyo) 2023; 71:792-797. [PMID: 37779082 DOI: 10.1248/cpb.c23-00435] [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] [Indexed: 10/03/2023]
Abstract
Chiral lithium binaphtholates prepared from the corresponding binaphthols and lithium tert-butoxide effectively catalyze the asymmetric Michael additions of ketones to poorly reactive acrylamides. The lithium binaphtholate catalyst mediates ketone deprotonation and enantioselective carbon-carbon bond formation to the acrylamide to deliver the Michael adduct in good yield and enantioselectivity. A small excess of lithium tert-butoxide relative to the binaphthol successfully enolizes the ketone in the initial stage of the reaction to promote the Michael reaction. Computational analysis of the transition state suggested that the 3- and 3'-phenyl groups of the binaphtholate catalyst regulate the orientation of the lithium enolate and the subsequent approach of the acrylamide, leading to superior enantioselectivity.
Collapse
Affiliation(s)
- Natsuho Harada
- Graduate School of Pharmaceutical Sciences, Kumamoto University
| | - Toshifumi Asano
- Graduate School of Pharmaceutical Sciences, Kumamoto University
| | | | - Shunsuke Kotani
- Graduate School of Pharmaceutical Sciences, Kumamoto University
| | - Makoto Nakajima
- Graduate School of Pharmaceutical Sciences, Kumamoto University
| |
Collapse
|
6
|
Zhang L, Liu Y, Wang T, Liu Z, Li W, Qiao ZA. Multi-Dimensional Molecular Self-Assembly Strategy for the Construction of Two-Dimensional Mesoporous Polydiaminopyridine and Carbon Materials. Small 2023; 19:e2205693. [PMID: 36408773 DOI: 10.1002/smll.202205693] [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] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 10/30/2022] [Indexed: 06/16/2023]
Abstract
Two-dimensional (2D) mesoporous polymers, combining the advantages of organic polymers, porous materials, and 2D materials, have received great attention in adsorption, catalysis, and energy storage. However, the synthesis of 2D mesoporous polymers is not only challenged by the complex 2D structure construction, but also by the low yield and difficulty in controlling the dynamics of the assembly during the generation of mesopores. Herein, a facile multi-dimensional molecular self-assembly strategy is reported for the preparation of 2D mesoporous polydiaminopyridines (MPDAPs), which features tunable pore sizes (17-35 nm) and abundant N content up to 18.0 at%. Benefitting from the abundant N sites, 2D nanostructure, and uniform-large mesopores, the 2D MPDAPs exhibit excellent catalytic performance for the Knoevenagel condensation reaction. After calcination under N2 atmosphere, the obtained 2D N-doped mesoporous carbon (NMCs) with large and uniform pore sizes, high surface areas, abundant N content (up to 23.1%), and a high ratio of basic N species (57.0% pyridinic N and 35.9% pyrrolic N) can show an excellent CO2 uptake density (11.7 µmol m-2 at 273 K), higher than previously reported porous materials.
Collapse
Affiliation(s)
- Liangliang Zhang
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun, Jilin, 130012, China
| | - Yumeng Liu
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun, Jilin, 130012, China
| | - Tao Wang
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun, Jilin, 130012, China
| | - Zhilin Liu
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun, Jilin, 130012, China
| | - Wei Li
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun, Jilin, 130012, China
| | - Zhen-An Qiao
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun, Jilin, 130012, China
| |
Collapse
|
7
|
Trunschke S, Piemontese E, Fuchs O, Abboud S, Seitz O. Enhancing Auxiliary-Mediated Native Chemical Ligation at Challenging Junctions with Pyridine Scaffolds. Chemistry 2022; 28:e202202065. [PMID: 36097325 PMCID: PMC10091703 DOI: 10.1002/chem.202202065] [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: 07/01/2022] [Indexed: 12/13/2022]
Abstract
To expand the scope of native chemical ligation (NCL) beyond reactions at cysteine, ligation auxiliaries are appended to the peptide N-terminus. After the introduction of a pyridine-containing auxiliary, which provided access to challenging junctions (proline or β-branched amino acids), we herein probe the role of the pyridine-ring nitrogen. We observed side reactions leading to preliminary auxiliary loss. We describe a new easy to attach β-mercapto-β-(4-methoxy-2-pyridinyl)-ethyl (MMPyE) auxiliary, which 1) has increased stability; 2) enables NCL at sterically encumbered junctions (e. g., Leu-Val); and 3) allows removal under mildly basic (pH 8.5) conditions was introduced. The synthesis of a 120 aa long peptide containing eight MUC5AC tandem repeats via ligation of two 60mers demonstrates the usefulness. Making use of hitherto unexplored NCL to tyrosine, the MMPyE auxiliary provided access to a head-to-tail-cyclized 21-mer peptide and a His6 -tagged hexaphosphorylated peptide comprising 6 heptapeptide repeats of the RNA polymerase II C-terminal domain.
Collapse
Affiliation(s)
- Sebastian Trunschke
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489, Berlin, Germany
| | - Emanuele Piemontese
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489, Berlin, Germany
| | - Olaf Fuchs
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489, Berlin, Germany
| | - Skander Abboud
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489, Berlin, Germany
| | - Oliver Seitz
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489, Berlin, Germany
| |
Collapse
|
8
|
Fischer M, Drabo P, Burow L, Delidovich I. Kinetic Salt Effect on Base-Catalyzed Isomerization of d-Glucose into d-Fructose. Chempluschem 2022; 87:e202200389. [PMID: 36539261 DOI: 10.1002/cplu.202200389] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [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: 11/04/2022] [Revised: 12/01/2022] [Indexed: 12/07/2022]
Abstract
Isomerization of d-glucose (Glc) into d-fructose (Fru) is of great importance for food sector as well as for valorization of lignocellulosic biomass. Soluble and solid bases exhibit high catalytic activity for the isomerization. Here, we report a salt effect on the base-catalyzed aqueous-phase Glc-Fru isomerization. Addition of soluble salts (Na2 SO4 , NaNO3 , K2 SO4 , and NaCl) results in an increased apparent reaction rate (factors of 1.5 to 6). The salt effect was observed both in the presence of soluble base NaOH at constant pH value and solid bases MgO, Li3 PO4 , and Mg-Al hydrotalcite. Apparent activation energy and UV absorption spectra were not significantly influenced by addition of salts. Potentiometric titration showed that the acidity constants of the saccharides increase in the presence of electrolytes. Since the rate of the isomerization depends on the thermodynamic acidity constant of Glc, the isomerization is accelerated by the presence of electrolytes.
Collapse
Affiliation(s)
- Matthias Fischer
- Institute for Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074, Aachen, Germany
| | - Peter Drabo
- Institute for Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074, Aachen, Germany
| | - Lutz Burow
- Institute for Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074, Aachen, Germany
| | - Irina Delidovich
- Institute for Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074, Aachen, Germany.,Institute of Chemical, Environmental and Bioscience Engineering, Technische Universität Wien, Getreidemarkt 9, 1060, Vienna, Austria
| |
Collapse
|
9
|
Fuchs O, Trunschke S, Hanebrink H, Reimann M, Seitz O. Enabling Cysteine-Free Native Chemical Ligation at Challenging Junctions with a Ligation Auxiliary Capable of Base Catalysis. Angew Chem Int Ed Engl 2021; 60:19483-19490. [PMID: 34165893 PMCID: PMC8457107 DOI: 10.1002/anie.202107158] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Indexed: 12/14/2022]
Abstract
Ligation auxiliaries are used in chemical protein synthesis to extend the scope of native chemical ligation (NCL) beyond cysteine. However, auxiliary-mediated ligations at sterically demanding junctions have been difficult. Often the thioester intermediate formed in the thiol exchange step of NCL accumulates because the subsequent S→N acyl transfer is extremely slow. Here we introduce the 2-mercapto-2-(pyridin-2-yl)ethyl (MPyE) group as the first auxiliary designed to aid the ligation reaction by catalysis. Notably, the MPyE auxiliary provides useful rates even for junctions containing proline or a β-branched amino acid. Quantum chemical calculations suggest that the pyridine nitrogen acts as an intramolecular base in a rate-determining proton transfer step. The auxiliary is prepared in two steps and conveniently introduced by reductive alkylation. Auxiliary cleavage is induced upon treatment with TCEP/morpholine in presence of a MnII complex as radical starter. The synthesis of a de novo designed 99mer peptide and an 80 aa long MUC1 peptide demonstrates the usefulness of the MPyE auxiliary.
Collapse
Affiliation(s)
- Olaf Fuchs
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489, Berlin, Germany
| | - Sebastian Trunschke
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489, Berlin, Germany
| | - Hendrik Hanebrink
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489, Berlin, Germany
| | - Marc Reimann
- Department of Chemistry, Technische Universität Berlin, Straße des 17. Juni 135, 10623, Berlin, Germany
| | - Oliver Seitz
- Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489, Berlin, Germany
| |
Collapse
|
10
|
Das S, Hu Q, Kondoh A, Terada M. Enantioselective Protonation: Hydrophosphinylation of 1,1-Vinyl Azaheterocycle N-Oxides Catalyzed by Chiral Bis(guanidino)iminophosphorane Organosuperbase. Angew Chem Int Ed Engl 2021; 60:1417-1422. [PMID: 33030798 DOI: 10.1002/anie.202012492] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [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: 09/14/2020] [Indexed: 12/30/2022]
Abstract
Enantioselective protonation by hydrophosphinylation of diarylphosphine oxides with 2-vinyl azaheterocycle N-oxide derivatives was demonstrated using chiral bis(guanidino)iminophosphorane as the higher-order organosuperbase catalyst. It was confirmed by several control experiments that a chiral weak conjugate acid of the chiral bis(guanidino)iminophosphorane, instead of achiral diarylphosphine oxides, directly functioned as the proton source to afford the corresponding product in a highly enantioselective manner in most cases. Enantioselective protonation by a weak conjugate acid generated from the higher-order organosuperbase would broaden the scope of enantioselective reaction systems because of utilization of a range of less acidic pronucleophiles. This method is highlighted by the valuable synthesis of a series of chiral P,N-ligands for chiral metal complexes through the reduction of phosphine oxide and N-oxide units of the corresponding product without loss of enantiomeric purity.
Collapse
Affiliation(s)
- Saikat Das
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai, 980-8578, Japan
| | - Qiupeng Hu
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai, 980-8578, Japan
| | - Azusa Kondoh
- Research and Analytical Center for Giant Molecules, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai, 980-8578, Japan
| | - Masahiro Terada
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai, 980-8578, Japan
| |
Collapse
|
11
|
Thiyagarajan S, Krishnakumar V, Gunanathan C. KOtBu-Catalyzed Michael Addition Reactions Under Mild and Solvent-Free Conditions. Chem Asian J 2020; 15:518-523. [PMID: 31957937 DOI: 10.1002/asia.201901647] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [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: 11/28/2019] [Revised: 12/29/2019] [Indexed: 11/10/2022]
Abstract
Designed transition metal complexes predominantly catalyze Michael addition reactions. Inorganic and organic base-catalyzed Michael addition reactions have been reported. However, known base-catalyzed reactions suffer from the requirement of solvents, additives, high pressure and also side-reactions. Herein, we demonstrate a mild and environmentally friendly strategy of readily available KOt Bu-catalyzed Michael addition reactions. This simple inorganic base efficiently catalyzes the Michael addition of underexplored acrylonitriles, esters and amides with (oxa-, aza-, and thia-) heteroatom nucleophiles. This catalytic process proceeds under solvent-free conditions and at room temperature. Notably, this protocol offers an easy operational procedure, broad substrate scope with excellent selectivity, reaction scalability and excellent TON (>9900). Preliminary mechanistic studies revealed that the reaction follows an ionic mechanism. Formal synthesis of promazine is demonstrated using this catalytic protocol.
Collapse
Affiliation(s)
- Subramanian Thiyagarajan
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), HBNI, Bhubaneswar, 752050, India
| | - Varadhan Krishnakumar
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), HBNI, Bhubaneswar, 752050, India
| | - Chidambaram Gunanathan
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), HBNI, Bhubaneswar, 752050, India
| |
Collapse
|
12
|
Roy BC, Ansari IA, Samim SA, Kundu S. Base-Promoted α-Alkylation of Arylacetonitriles with Alcohols. Chem Asian J 2019; 14:2215-2219. [PMID: 31046180 DOI: 10.1002/asia.201900285] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [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: 02/26/2019] [Revised: 04/30/2019] [Indexed: 01/13/2023]
Abstract
A practical method to synthesize α-alkylated arylacetonitriles from arylacetonitriles and alcohols without using any expensive transition metal complexes is demonstrated here. Following this base-catalysed sustainable procedure, various arylacetonitriles were successfully alkylated with different alcohols. The practical applicability of this protocol was extended by one-pot synthesis of important carboxylic acid derivatives.
Collapse
Affiliation(s)
| | | | - Sk Abdus Samim
- Department of Chemistry, IIT Kanpur, Kanpur, 208016, UP, India
| | - Sabuj Kundu
- Department of Chemistry, IIT Kanpur, Kanpur, 208016, UP, India
| |
Collapse
|
13
|
Wawrzynczak A, Nowak I, Feliczak-Guzik A. Toward Exploiting the Behavior of Niobium-Containing Mesoporous Silicates vs. Polyoxometalates in Catalysis. Front Chem 2018; 6:560. [PMID: 30525023 PMCID: PMC6258736 DOI: 10.3389/fchem.2018.00560] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 10/29/2018] [Indexed: 11/13/2022] Open
Abstract
Classification of polyoxometalates (POMs) is based on their chemical composition, basically represented by two general formulae: a) [MmOy]p- b) [XxMmOy]q-, where M is the main transition metal, O is the oxygen atom and X can be a non-metal atom such as Si. Additionally, in the most cases, the structure of the polyoxometalates is derived from a combination of octahedral units MO6 with a central metal atom M and the oxygen atoms placed at their corners. In such octahedra, oxygen atoms allow the condensation between two octahedral units, while one oxygen atom (or max. two atoms) makes double bond with the central metal atom and is not shared with other metal atoms within the complex (terminal oxygens). On the other hand, niobium-containing mesoporous silicates contain mainly MO4 tetrahedra and reveal superior activity in heterogeneous catalysis. Thus, the proper coordination of niobium is crucial for the catalytic activity and will be deeply discussed. The similarity in the catalytic behavior of niobium-polyoxometalates and heterogeneous niobium single-site catalysts in selective oxidations will be demonstrated.
Collapse
Affiliation(s)
| | - Izabela Nowak
- Faculty of Chemistry, Adam Mickiewicz University in Poznań, Poznań, Poland
| | | |
Collapse
|
14
|
Debler EW, Ito S, Seebeck FP, Heine A, Hilvert D, Wilson IA. Structural origins of efficient proton abstraction from carbon by a catalytic antibody. Proc Natl Acad Sci U S A 2005; 102:4984-9. [PMID: 15788533 PMCID: PMC555987 DOI: 10.1073/pnas.0409207102] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [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: 12/09/2004] [Indexed: 11/18/2022] Open
Abstract
Antibody 34E4 catalyzes the conversion of benzisoxazoles to salicylonitriles with high rates and multiple turnovers. The crystal structure of its complex with the benzimidazolium hapten at 2.5-angstroms resolution shows that a combination of hydrogen bonding, pi stacking, and van der Waals interactions is exploited to position both the base, Glu(H50), and the substrate for efficient proton transfer. Suboptimal placement of the catalytic carboxylate, as observed in the 2.8-angstroms structure of the Glu(H50)Asp variant, results in substantially reduced catalytic efficiency. In addition to imposing high positional order on the transition state, the antibody pocket provides a highly structured microenvironment for the reaction in which the carboxylate base is activated through partial desolvation, and the highly polarizable transition state is stabilized by dispersion interactions with the aromatic residue Trp(L91) and solvation of the leaving group oxygen by external water. The enzyme-like efficiency of general base catalysis in this system directly reflects the original hapten design, in which a charged guanidinium moiety was strategically used to elicit an accurately positioned functional group in an appropriate reaction environment and suggests that even larger catalytic effects may be achievable by extending this approach to the induction of acid-base pairs capable of bifunctional catalysis.
Collapse
Affiliation(s)
- Erik W Debler
- Department of Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | | | | | | | | | | |
Collapse
|