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Intelli AJ, Pal M, Selvaraju M, Altman RA. Palladium-Catalyzed Dearomatization of Benzothiophenes: Isolation and Functionalization of a Discrete Dearomatized Intermediate. SYNTHESIS-STUTTGART 2023; 55:3568-3574. [PMID: 37915377 PMCID: PMC10617892 DOI: 10.1055/a-2092-9012] [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] [Indexed: 11/03/2023]
Abstract
A Pd-catalyzed decarboxylative dearomatization reaction of a heterocyclic substrate enables access to an uncommon reaction intermediate that rearomatizes in the presence of amine bases in a net C-H functionalization sequence. The dearomatized benzo[b]thiophene intermediate bears an exocyclic alkene that can be functionalized through cycloaddition and halogenation reactions to deliver complex heterocyclic products.
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Affiliation(s)
- Andrew John Intelli
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47907, United States
| | - Mohan Pal
- NuChem Sciences Inc.; 2350 Rue Cohen Suite 201, Saint-Laurent, Quebec, Canada H4R 2N6
| | | | - Ryan A Altman
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47907, United States
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
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2
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Intelli AJ, Lee RT, Altman RA. Peroxide-Initiated Hydrophosphinylation of gem-Difluoroalkenes. J Org Chem 2023; 88:14012-14021. [PMID: 37738112 PMCID: PMC10591976 DOI: 10.1021/acs.joc.3c01562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/24/2023]
Abstract
The installation of fluorine and fluorinated functional groups into drug-like scaffolds can perturb the physicochemical, pharmacokinetic, and pharmacodynamic properties of compounds. However, some potentially useful fluorinated substructures reside predominantly outside the realm of the current synthetic methodologies. One such substructure, the α,α-difluorophosphine oxide, might be convergently prepared by the reaction of a gem-difluorinated alkene with a P-H bond, though such nucleophilic reactions instead proceed through a C-F substitution pathway that delivers monofluorovinyl products. In contrast, we report a peroxide-initiated hydrophosphinylation reaction of gem-difluoroalkenes that avoids C-F substitution and produces a wide range of α,α-difluorophosphine oxides and functions using readily available reagents and green solvents.
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Affiliation(s)
- Andrew J Intelli
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47906, United States
| | - Ryan T Lee
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47906, United States
| | - Ryan A Altman
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47906, United States
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47906, United States
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3
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Herrick RM, Abd El-Gaber MK, Coy G, Altman RA. A diselenide additive enables photocatalytic hydroalkoxylation of gem-difluoroalkenes. Chem Commun (Camb) 2023; 59:5623-5626. [PMID: 37082905 PMCID: PMC10164105 DOI: 10.1039/d3cc01012k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2023]
Abstract
A photocatalytic hydroalkoxylation reaction enables the coupling of aliphatic alcohols with gem-difluoroalkenes, expanding the scope of accessible α,α-difluorinated ethers, a desirable substructure for medicinal and agricultural chemists. This reaction exploits an uncommon diselenide co-catalyst to facilitate the net hydrofunctionalization process, which contrasts alternate single-electron reactions that deliver dioxidation products. Future use of this co-catalyst might enable other currently unknown photocatalytic reactions.
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Affiliation(s)
- Ryan M Herrick
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47906, USA.
| | - Mohammed K Abd El-Gaber
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47906, USA.
- Medicinal Chemistry Department, Faculty of Pharmacy, Assiut University, Assiut 71526, Egypt
| | - Gabriela Coy
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47906, USA.
- Department of Pharmacy, Universidad Nacional de Colombia, Bogota 111321, Colombia
| | - Ryan A Altman
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47906, USA.
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47906, USA
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4
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Sorrentino JP, Herrick RM, Abd El-Gaber MK, Abdelazem AZ, Kumar A, Altman RA. General Co-catalytic Hydrothiolation of gem-Difluoroalkenes. J Org Chem 2022; 87:16676-16690. [PMID: 36469658 PMCID: PMC9772298 DOI: 10.1021/acs.joc.2c02343] [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] [Indexed: 12/12/2022]
Abstract
Regioselective functionalization of gem-difluoroalkenes enables convergent late-stage access to fluorinated functional groups, though most functionalization reactions proceed through defluorinative functionalization processes that deliver mono-fluorovinyl products. In contrast, fewer reactions undergo net hydrofunctionalization to generate difluorinated products. Herein, we report a photocatalytic hydrothiolation of gem-difluoroalkenes that enables access to a broad spectrum of α,α-difluoroalkylthioethers. Notably, the reaction successfully couples nonactivated substrates, which expands the scope of accessible molecules relative to previously reported reactions involving organo- or photocatalytic strategies. Further, this reaction successfully couples biologically relevant molecules under aqueous conditions, highlighting potential applications in both late-stage and biorthogonal functionalizations.
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Affiliation(s)
- Jacob P. Sorrentino
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, United States
| | - Ryan M. Herrick
- Department of Medicinal Chemistry and Molecular Pharmacology Purdue University, West Lafayette, Indiana 47906, United States
| | - Mohammed K. Abd El-Gaber
- Department of Medicinal Chemistry and Molecular Pharmacology Purdue University, West Lafayette, Indiana 47906, United States
- Medicinal Chemistry Department, Faculty of Pharmacy, Assiut University, Assiut 71526, Egypt
| | - Ahmed Z. Abdelazem
- Department of Medicinal Chemistry and Molecular Pharmacology Purdue University, West Lafayette, Indiana 47906, United States
- Biotechnology & Life Sciences Department, Faculty of Postgraduate Studies for Advanced Sciences, Beni-Suef University, Beni-Suef 62517, Egypt
| | - Ankit Kumar
- Department of Medicinal Chemistry and Molecular Pharmacology Purdue University, West Lafayette, Indiana 47906, United States
- Department of Chemistry, University of Delhi, Delhi 110007, India
| | - Ryan A. Altman
- Department of Medicinal Chemistry and Molecular Pharmacology Purdue University, West Lafayette, Indiana 47906, United States
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47906, United States
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5
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Altman RA. In This Issue, Volume 13, Issue 12. ACS Med Chem Lett 2022. [PMCID: PMC9743418 DOI: 10.1021/acsmedchemlett.2c00485] [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: 12/13/2022] Open
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6
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Koley S, Cayton KT, González-Montiel GA, Yadav MR, Orsi DL, Intelli AJ, Cheong PHY, Altman RA. Cu(II)-Catalyzed Unsymmetrical Dioxidation of gem-Difluoroalkenes to Generate α,α-Difluorinated-α-phenoxyketones. J Org Chem 2022; 87:10710-10725. [PMID: 35914193 PMCID: PMC9391295 DOI: 10.1021/acs.joc.2c00925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 11/30/2022]
Abstract
A Cu-based catalyst system convergently couples gem-difluoroalkenes with phenols under aerobic conditions to deliver α,α-difluorinated-α-phenoxyketones, an unstudied hybrid fluorinated functional group. Composed of α,α-difluorinated ketone and α,α-difluorinated ether moieties, these compounds have rarely been reported as a synthetic intermediate. Computational predictions and later experimental corroboration suggest that the phenoxy-substituted fluorinated ketone's sp3-hybridized hydrate form is energetically favored relative to the respective nonether variant and that perturbation of the electronic character of the ketone can further encourage the formation of the hydrate. The more facile conversion between ketone and hydrate forms suggests that analogues should readily covalently inhibit proteases and other enzymes. Further functionalization of the ketone group enables access to other useful fluorinated functional groups.
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Affiliation(s)
- Suvajit Koley
- Department of Medicinal Chemistry and Molecular Pharmacology; Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA
| | - Kaylee T. Cayton
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, USA
| | | | - M. Ramu Yadav
- Department of Chemistry, MS-723, IIT Delhi, Hauz Khas, New Delhi, India 110016
| | - Douglas L. Orsi
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts 02142, USA
| | - Andrew J. Intelli
- Department of Medicinal Chemistry and Molecular Pharmacology; Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA
| | - Paul Ha-Yeon Cheong
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, USA
| | - Ryan A. Altman
- Department of Medicinal Chemistry and Molecular Pharmacology; Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA
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Altman RA, Brai A, Golden J, La Regina G, Li Z, Moore TW, Pomerantz WCK, Rajapaksa NS, Adams AM. An Innovation 10 Years in the Making: The Stories in the Pages of ACS Medicinal Chemistry Letters. ACS Med Chem Lett 2022; 13:540-545. [PMID: 35450346 PMCID: PMC9014514 DOI: 10.1021/acsmedchemlett.1c00623] [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] [Received: 11/07/2021] [Accepted: 12/01/2021] [Indexed: 11/29/2022] Open
Abstract
Innovation in medicinal chemistry has been at the heart of ACS Medicinal Chemistry Letters since the journal's founding 10 years ago. In his inaugural editorial, Editor-in-Chief Dennis Liotta laid out a vision for the journal to become the "premier international journal for rapid communication of cutting-edge studies," and, after 10 years, it has become exactly that. The great hope of drug discovery scientists is that their innovations will lead to new therapeutics to treat unmet medical needs. In the spirit of innovation and in celebration of the recent 10th anniversary of ACS Med. Chem. Lett., we highlight five therapeutics that were first reported or first comprehensively characterized within ACS Med. Chem. Lett.. This overview also serves to introduce the expansion of the scope of the Innovations article type to include Topical Innovations. With this extension, the journal hopes to provide a forum to showcase concise (rather than comprehensive) reviews of topics that are both timely and of great interest to the medicinal chemistry community. Moreover, these articles will emphasize the next steps to move the field toward new areas of interest in medicinal chemistry. Appropriate topics might include case studies of clinical candidates or approved drugs, new assay technologies in drug discovery, novel target classes, and innovative new approaches towards modulation of human physiology. Since its founding 10 years ago, ACS Med. Chem. Lett. has established itself as a venue for the rapid communication of studies in medicinal chemistry and drug discovery. There have been several drugs and clinical candidates that were first reported or first comprehensively characterized in ACS Med. Chem. Lett. In celebration of the 10th anniversary of ACS Med. Chem. Lett. this Topical Innovations article highlights five of these compounds: Ivosidenib, Siponimod, Glasdegib, Parsaclisib, and Dabrafenib.
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Affiliation(s)
- Ryan A. Altman
- Department of Medicinal Chemistry and Molecular Pharmacology and Department of Chemistry, Purdue University, West Lafayette, Indiana 47906, United States
| | - Annalaura Brai
- Laboratory affiliated to Istituto Pasteur Italia - Fondazione Cenci Bolognetti, Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, Piazzale Aldo Moro 5, Rome 00185, Italy
| | - Jennifer Golden
- School of Pharmacy, Pharmaceutical Sciences Division, University of Wisconsin─Madison, Madison, Wisconsin 53705, United States
| | - Giuseppe La Regina
- Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza University of Rome, Rome 00185, Italy
| | - Zhengqiu Li
- School of Pharmacy, Jinan University, 601 Huangpu Avenue West, Guangzhou 510632, China
| | - Terry W. Moore
- Pharmaceutical Sciences, University of Illinois at Chicago, 833 S. Wood Street, Chicago, Illinois 60612, United States
| | - William C. K. Pomerantz
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Naomi S. Rajapaksa
- Medicinal Chemistry, Interline Therapeutics, 620 Utah Ave, South San Francisco, California 94080, United States
| | - Ashley M. Adams
- Medicine Science and Technology, GlaxoSmithKline, 1250 South Collegeville Road, Collegeville, Pennsylvania 19426, United States
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8
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Sorrentino JP, Altman RA. Fluoroalkylation of Dextromethorphan Improves CNS Exposure and Metabolic Stability. ACS Med Chem Lett 2022; 13:707-713. [PMID: 35450379 PMCID: PMC9014517 DOI: 10.1021/acsmedchemlett.2c00055] [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] [Received: 02/11/2022] [Accepted: 03/11/2022] [Indexed: 11/28/2022] Open
Abstract
Aryl-methyl ethers, while present in many bioactive compounds, are subject to rapid O-dealkylation, which can generate bioinactive or toxic metabolites. Such is the case for dextromethorphan, which readily undergoes P450 mediated O-dealkylation to provide the psychoactive phenolic metabolite dextrorphan, an N-methyl-d-aspartate (NMDA) receptor antagonist that causes hallucinations and encourages recreational abuse. As a general strategy to minimize this undesired degradation, both deuteration and fluorination strategies might be exploited, though such strategies have rarely been compared in matched series. In this manuscript, we designed, synthesized, and evaluated in vitro and in vivo new fluoroalkyl analogs of dextromethorphan and D3-dextromethorphan that minimize metabolic degradation and increased CNS exposure relative to dextromethorphan and related deuterated analogs currently in clinical trials.
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Affiliation(s)
- Jacob P. Sorrentino
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Ryan A. Altman
- Department of Medicinal Chemistry and Molecular Pharmacology and Department of Chemistry, Purdue University, West Lafayette, Indiana 47906, United States
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9
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Altman RA. In This Issue, Volume 13, Issue 3. ACS Med Chem Lett 2022. [DOI: 10.1021/acsmedchemlett.2c00069] [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: 11/29/2022] Open
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10
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Sharma KK, Cassell RJ, Meqbil YJ, Su H, Blaine AT, Cummins BR, Mores KL, Johnson DK, van Rijn RM, Altman RA. Modulating β-arrestin 2 recruitment at the δ- and μ-opioid receptors using peptidomimetic ligands. RSC Med Chem 2021; 12:1958-1967. [PMID: 34825191 DOI: 10.1039/d1md00025j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 08/11/2021] [Indexed: 12/21/2022] Open
Abstract
μ-Opioid receptor agonists provide potent and effective acute analgesia; however, their therapeutic window narrows considerably upon repeated administration, such as required for treating chronic pain. In contrast, bifunctional μ/δ opioid agonists, such as the endogenous enkephalins, have potential for treating both acute and chronic pain. However, enkephalins recruit β-arrestins, which correlate with certain adverse effects at μ- and δ-opioid receptors. Herein, we identify the C-terminus of Tyr-ψ[(Z)CF[double bond, length as m-dash]CH]-Gly-Leu-enkephalin, a stable enkephalin derivative, as a key site to regulate bias of both δ- and μ-opioid receptors. Using in vitro assays, substitution of the Leu5 carboxylate with amides (NHEt, NMe2, NCyPr) reduced β-arrestin recruitment efficacy through both the δ-opioid and μ-opioid, while retaining affinity and cAMP potency. For this series, computational studies suggest key ligand-receptor interactions that might influence bias. These findings should enable the discovery of a range of tool compounds with previously unexplored biased μ/δ opioid agonist pharmacological profiles.
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Affiliation(s)
- Krishna K Sharma
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University USA
| | - Robert J Cassell
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University USA
| | - Yazan J Meqbil
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University USA .,Computational Interdisciplinary Graduate Program (CIGP), Purdue University USA
| | - Hongyu Su
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University USA
| | - Arryn T Blaine
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University USA .,Purdue Interdisciplinary Life Science Graduate Program, Purdue University USA
| | | | - Kendall L Mores
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University USA
| | - David K Johnson
- Computational Chemical Biology Core and Molecular Graphics and Modeling Laboratory, The University of Kansas USA
| | - Richard M van Rijn
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University USA .,Purdue Institute for Drug Discovery, Purdue University USA.,Purdue Institute for Integrative Neuroscience, Purdue University USA
| | - Ryan A Altman
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University USA .,Department of Chemistry, Purdue University USA
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11
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Abstract
gem-Difluoroalkenes are readily available fluorinated building blocks, and the fluorine-induced electronic perturbations of the alkenes enables a wide array of selective functionalization reactions. However, many reactions of gem-difluoroalkenes result in a net C─F functionalization to generate monofluorovinyl products or addition of F to generate trifluoromethyl-containing products. In contrast, fluorine-retentive strategies for the functionalization of gem-difluoroalkenes remain less generally developed, and is now becoming a rapidly developing area. This review will present the development of fluorine-retentive strategies including electrophilic, nucleophilic, radical, and transition metal catalytic strategies with an emphasis on key physical organic and mechanistic aspects that enable reactivities.
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Affiliation(s)
- Jacob P Sorrentino
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Ryan A Altman
- Department of Medicinal Chemistry and Molecular Pharmacology and Department of Chemistry, Purdue University, West Lafayette, Indiana 47906, United States
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12
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Altman RA. In This Issue, Volume 12, Issue 5. ACS Med Chem Lett 2021. [DOI: 10.1021/acsmedchemlett.1c00212] [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: 11/30/2022] Open
Affiliation(s)
- Ryan A. Altman
- Department of Medicinal Chemistry and Molecular Pharmacology, Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
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13
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Sorrentino JP, Orsi DL, Altman RA. Correction to "Acid-Catalyzed Hydrothiolation of gem-Difluorostyrenes to Access α,α-Difluoroalkylthioethers". J Org Chem 2021; 86:4374. [PMID: 33621093 DOI: 10.1021/acs.joc.1c00395] [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: 11/29/2022]
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Abstract
The substitution of hydrogen atoms with fluorine in bioactive molecules can greatly impact physicochemical, pharmacokinetic, and pharmacodynamic properties. However, current synthetic methods cannot readily access many fluorinated motifs, which impedes utilization of these groups. Thus, the development of new methods to introduce fluorinated functional groups is critical for developing the next generation of biological probes and therapeutic agents. The synthesis of one such substructure, the α,α-difluoroalkylthioether, typically requires specialized conditions that necessitate early-stage installation. A late-stage and convergent approach to access α,α-difluoroalkylthioethers could involve nucleophilic addition of thiols across gem-difluorostyrenes. Unfortunately, under basic conditions, nucleophilic addition to gem-difluorostyrenes generates an anionic intermediate that can undergo facile elimination of fluoride to generate α-fluorovinylthioethers. To overcome this decomposition, we herein exploit an acid-based catalyst system to facilitate simultaneous nucleophilic addition and protonation of the unstable intermediate. Ultimately, the optimized mild conditions afford the desired α,α-difluoroalkylthioethers in high selectivity and moderate to excellent yields. These α,α-difluoroalkylthioethers are less nucleophilic and more oxidatively stable relative to nonfluorinated thioethers, suggesting the potential application of this unexplored functional group in biological probes and therapeutic agents.
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Affiliation(s)
- Jacob P. Sorrentino
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Douglas L. Orsi
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts 02142, United States
| | - Ryan A. Altman
- Department of Medicinal Chemistry and Molecular Pharmacology and Department of Chemistry, Purdue University, West Lafayette, Indiana 47906, United States
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15
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Yang Y, Borel T, de Azambuja F, Johnson D, Sorrentino JP, Udokwu C, Davis I, Liu A, Altman RA. Diflunisal Derivatives as Modulators of ACMS Decarboxylase Targeting the Tryptophan-Kynurenine Pathway. J Med Chem 2020; 64:797-811. [PMID: 33369426 DOI: 10.1021/acs.jmedchem.0c01762] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In the kynurenine pathway for tryptophan degradation, an unstable metabolic intermediate, α-amino-β-carboxymuconate-ε-semialdehyde (ACMS), can nonenzymatically cyclize to form quinolinic acid, the precursor for de novo biosynthesis of nicotinamide adenine dinucleotide (NAD+). In a competing reaction, ACMS is decarboxylated by ACMS decarboxylase (ACMSD) for further metabolism and energy production. Therefore, the inhibition of ACMSD increases NAD+ levels. In this study, an Food and Drug Administration (FDA)-approved drug, diflunisal, was found to competitively inhibit ACMSD. The complex structure of ACMSD with diflunisal revealed a previously unknown ligand-binding mode and was consistent with the results of inhibition assays, as well as a structure-activity relationship (SAR) study. Moreover, two synthesized diflunisal derivatives showed half-maximal inhibitory concentration (IC50) values 1 order of magnitude better than diflunisal at 1.32 ± 0.07 μM (22) and 3.10 ± 0.11 μM (20), respectively. The results suggest that diflunisal derivatives have the potential to modulate NAD+ levels. The ligand-binding mode revealed here provides a new direction for developing inhibitors of ACMSD.
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Affiliation(s)
- Yu Yang
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Timothy Borel
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
| | | | - David Johnson
- Computational Chemical Biology Core and Molecular Graphics and Modeling Laboratory, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Jacob P Sorrentino
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Chinedum Udokwu
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Ian Davis
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Aimin Liu
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Ryan A Altman
- Department of Medicinal Chemistry and Molecular Pharmacology and Department of Chemistry, Purdue University, 575 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
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16
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Yuan K, Feoktistova T, Cheong PHY, Altman RA. Arylation of gem-difluoroalkenes using a Pd/Cu Co-catalytic system that avoids β-fluoride elimination. Chem Sci 2020; 12:1363-1367. [PMID: 34163899 PMCID: PMC8179108 DOI: 10.1039/d0sc05192f] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
PdII/CuI co-catalyze an arylation reaction of gem-difluoroalkenes using arylsulfonyl chlorides to deliver α,α-difluorobenzyl products. The reaction proceeds through a β,β-difluoroalkyl-Pd intermediate that typically undergoes unimolecular β-F elimination to deliver monofluorinated alkene products in a net C-F functionalization reaction. However to avoid β-F elimination, we offer the β,β-difluoroalkyl-Pd intermediate an alternate low-energy route involving β-H elimination to ultimately deliver difluorinated products in a net arylation/isomerization sequence. Overall, this reaction enables exploration of new reactivities of unstable fluorinated alkyl-metal species, while also providing new opportunities for transforming readily available fluorinated alkenes into more elaborate substructures.
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Affiliation(s)
- Kedong Yuan
- Tianjin Key Laboratory of Advanced Functional Porous Materials, Institute for New Energy Materials & Low-Carbon Technologies, School of Materials Science and Engineering, Tianjin University of Technology Tianjin 300384 P. R. China
| | - Taisiia Feoktistova
- Department of Chemistry, Oregon State University 153 Gilbert Hall Corvallis OR USA
| | - Paul Ha-Yeon Cheong
- Department of Chemistry, Oregon State University 153 Gilbert Hall Corvallis OR USA
| | - Ryan A Altman
- Department of Medicinal Chemistry and Molecular Pharmacology, Department of Chemistry, Purdue University West Lafayette IN 47907 USA
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Altman RA, Pomerantz WCK. In This Issue, Volume 11, Issue 10 (“Medicinal Chemistry: From Targets to Therapies” Special Issue). ACS Med Chem Lett 2020. [DOI: 10.1021/acsmedchemlett.0c00507] [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: 11/28/2022] Open
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18
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Altman RA. In This Issue, Volume 11, Issue 9. ACS Med Chem Lett 2020. [DOI: 10.1021/acsmedchemlett.0c00459] [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: 11/28/2022] Open
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Abstract
gem-Difluoroalkenes represent valuable synthetic handles for organofluorine chemistry; however, most reactions of this substructure proceed through reactive intermediates prone to eliminate a fluorine atom and generate monofluorinated products. Taking advantage of the distinct reactivity of gem-difluoroalkenes, we present a cobalt-catalyzed regioselective unsymmetrical dioxygenation of gem-difluoroalkenes using phenols and molecular oxygen, which retains both fluorine atoms and provides β-phenoxy-β,β-difluorobenzyl alcohols. Mechanistic studies suggest that the reaction operates through a radical chain process initiated by Co(II)/O2/phenol and quenched by the Co-based catalyst. This mechanism enables the retention of both fluorine atoms, which contrasts most transition-metal-catalyzed reactions of gem-difluoroalkenes that typically involve defluorination.
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Affiliation(s)
- Douglas L Orsi
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Justin T Douglas
- Molecular Structures Group, Nuclear Magnetic Resonance Laboratory, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Jacob P Sorrentino
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Ryan A Altman
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47907, United States.,Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
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20
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Sorrentino JP, Ambler BR, Altman RA. Late-Stage Conversion of a Metabolically Labile Aryl Methyl Ether-Containing Natural Product to Fluoroalkyl Analogues. J Org Chem 2020; 85:5416-5427. [PMID: 32191836 DOI: 10.1021/acs.joc.0c00125] [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: 12/22/2022]
Abstract
We report the conversion of aryl methyl ethers and phenols into six fluoroalkyl analogues through late-stage functionalization of a natural product-derived FDA-approved therapeutic. This series of short synthetic sequences exploits a combination of both modern and traditional methods and demonstrates that some recently reported methods do not always work as well as desired on a natural product-like scaffold. Nonetheless, reaction optimization can deliver sufficient quantities of each target analogue for medicinal chemistry purposes. In some cases, classical reactions and synthetic sequences still outcompete modern organofluorine transformations, which should encourage the continued search for improved reactions. Overall, the project provides a valuable synthetic roadmap for medicinal chemists to access a range of fluorinated therapeutic candidates with distinct physicochemical properties relative to the original O-based analogue.
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Affiliation(s)
- Jacob P Sorrentino
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Brett R Ambler
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States.,Department of Discovery Chemistry MRL, Merck & Co., Inc., 770 Sumneytown Pike, West Point, Pennsylvania 19486, United States
| | - Ryan A Altman
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
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21
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de Azambuja F, Yang MH, Feoktistova T, Selvaraju M, Brueckner AC, Grove MA, Koley S, Cheong PHY, Altman RA. Connecting remote C-H bond functionalization and decarboxylative coupling using simple amines. Nat Chem 2020; 12:489-496. [PMID: 32152476 PMCID: PMC7192790 DOI: 10.1038/s41557-020-0428-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [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: 04/28/2018] [Accepted: 01/23/2020] [Indexed: 01/01/2023]
Abstract
Transition metal-catalyzed C–H functionalization and decarboxylative coupling are two of the most notable synthetic strategies developed in the last 30 years. Herein, we connect these two reaction pathways using bases and a simple Pd-based catalyst system to promote a para-selective C–H functionalization reaction from benzylic electrophiles. Experimental and computational mechanistic studies suggest a pathway involving an uncommon Pd-catalyzed dearomatization of the benzyl moiety followed by a base-enabled rearomatization through a formal 1,5-hydrogen migration. This reaction complements “C–H activation” strategies that convert inert C–H bonds into C–metal bonds prior to C–C bond formation. Instead, this reaction exploits an inverted sequence and promotes C–C bond formation prior to deprotonation. These studies provide an opportunity to develop general para-selective C–H functionalization reactions from benzylic electrophiles and show how new reactive modalities may be accessed with careful control of reaction conditions.
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Affiliation(s)
- Francisco de Azambuja
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, KS, USA.,Department of Chemistry, KU Leuven, Leuven, Belgium
| | - Ming-Hsiu Yang
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, KS, USA.,The Scripps Research Institute, La Jolla, CA, USA
| | | | | | | | - Markas A Grove
- Department of Chemistry, Oregon State University, Corvallis, OR, USA
| | - Suvajit Koley
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, KS, USA
| | | | - Ryan A Altman
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, KS, USA.
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22
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Koley S, Altman RA. Recent Advances in Transition Metal-Catalyzed Functionalization of gem-Difluoroalkenes. Isr J Chem 2020; 60:313-339. [PMID: 32523163 PMCID: PMC7286626 DOI: 10.1002/ijch.201900173] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [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: 12/16/2019] [Accepted: 02/17/2020] [Indexed: 11/11/2022]
Abstract
gem-Difluorinated alkenes are readily accessible building blocks that can undergo functionalization to provide a broad spectrum of fluorinated and non-fluorinated products. Herein, we review recent (since 2017) transition metal-catalyzed transformations of these specialized alkenes and summarize general reactivity patterns of these reactions. Many transition metal-catalyzed reactions undergo net C-F bond functionalization reactions to deliver monofluorinated products. These reactions typically proceed through β-fluoro alkylmetal intermediates that readily eliminate a β-fluoride to deliver monofluoroalkene products. A second series of reactions exploit coinage metal fluorides to add F- to the gem-difluorinated alkene, and further functionalization delivers trifluoromethyl-containing products. In stark contrast, few transition metal-catalyzed reactions proceed in net "fluorine-retentive processes" to deliver difluoromethylene-based products.
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Affiliation(s)
- Suvajit Koley
- Department of Medicinal Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas, 66045, USA
| | - Ryan A Altman
- Department of Medicinal Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas, 66045, USA
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23
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Cassell RJ, Sharma KK, Su H, Cummins BR, Cui H, Mores KL, Blaine AT, Altman RA, van Rijn RM. The Meta-Position of Phe 4 in Leu-Enkephalin Regulates Potency, Selectivity, Functional Activity, and Signaling Bias at the Delta and Mu Opioid Receptors. Molecules 2019; 24:molecules24244542. [PMID: 31842282 PMCID: PMC6943441 DOI: 10.3390/molecules24244542] [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] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 12/08/2019] [Accepted: 12/10/2019] [Indexed: 01/10/2023] Open
Abstract
As tool compounds to study cardiac ischemia, the endogenous δ-opioid receptors (δOR) agonist Leu5-enkephalin and the more metabolically stable synthetic peptide (d-Ala2, d-Leu5)-enkephalin are frequently employed. However, both peptides have similar pharmacological profiles that restrict detailed investigation of the cellular mechanism of the δOR’s protective role during ischemic events. Thus, a need remains for δOR peptides with improved selectivity and unique signaling properties for investigating the specific roles for δOR signaling in cardiac ischemia. To this end, we explored substitution at the Phe4 position of Leu5-enkephalin for its ability to modulate receptor function and selectivity. Peptides were assessed for their affinity to bind to δORs and µ-opioid receptors (µORs) and potency to inhibit cAMP signaling and to recruit β-arrestin 2. Additionally, peptide stability was measured in rat plasma. Substitution of the meta-position of Phe4 of Leu5-enkephalin provided high-affinity ligands with varying levels of selectivity and bias at both the δOR and µOR and improved peptide stability, while substitution with picoline derivatives produced lower-affinity ligands with G protein biases at both receptors. Overall, these favorable substitutions at the meta-position of Phe4 may be combined with other modifications to Leu5-enkephalin to deliver improved agonists with finely tuned potency, selectivity, bias and drug-like properties.
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MESH Headings
- Animals
- CHO Cells
- Cricetulus
- Enkephalin, Leucine/genetics
- Enkephalin, Leucine/pharmacology
- Humans
- Phenylalanine
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, delta/genetics
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/genetics
- Receptors, Opioid, mu/metabolism
- Signal Transduction/drug effects
- Signal Transduction/genetics
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Affiliation(s)
- Robert J. Cassell
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; (R.J.C.); (H.S.); (K.L.M.); (A.T.B.)
| | - Krishna K. Sharma
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, KS 66045, USA;
| | - Hongyu Su
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; (R.J.C.); (H.S.); (K.L.M.); (A.T.B.)
| | | | - Haoyue Cui
- College of Wuya, Shenyang Pharmaceutical University, Shenyang 110016, China;
| | - Kendall L. Mores
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; (R.J.C.); (H.S.); (K.L.M.); (A.T.B.)
| | - Arryn T. Blaine
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; (R.J.C.); (H.S.); (K.L.M.); (A.T.B.)
| | - Ryan A. Altman
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, KS 66045, USA;
- Correspondence: (R.A.A.); (R.M.v.R.)
| | - Richard M. van Rijn
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA; (R.J.C.); (H.S.); (K.L.M.); (A.T.B.)
- Purdue Institute for Drug Discovery, Purdue University, West Lafayette, IN 47907, USA
- Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
- Correspondence: (R.A.A.); (R.M.v.R.)
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24
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Abstract
Gem-difluoroalkenes are an easily accessed fluorinated functional group, and a useful intermediate for elaborating into more complex fluorinated compounds. Currently, most functionalization reactions of gem-difluoroalkenes, with or without a transition metal-based catalyst system, involve the addition or removal of a fluorine atom to generate trifluorinated or monofluorinated products, respectively. In contrast, we present a complementary "fluorine-retentive" reaction that exploits an organocatalytic strategy to add phenols across gem-difluoroalkenes to deliver β,β-difluorophenethyl arylethers. The products are produced in good to moderate yields and selectivities, thus providing a range of compounds that are underrepresented in the synthetic and medicinal chemistry literature.
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Affiliation(s)
- Douglas L Orsi
- The University of Kansas, Department of Medicinal Chemistry, Lawrence, KS 66045
| | - M Ramu Yadav
- The University of Kansas, Department of Medicinal Chemistry, Lawrence, KS 66045
| | - Ryan A Altman
- The University of Kansas, Department of Medicinal Chemistry, Lawrence, KS 66045
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25
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Han C, Alabanza LM, Kelly SM, Orsi DL, Gosselin F, Altman RA. BBDFA: A Practical Reagent for Trifluoromethylation of Allylic and Benzylic Alcohols on Preparative Scale. Org Process Res Dev 2019. [DOI: 10.1021/acs.oprd.9b00201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Chong Han
- Department of Small Molecule Process Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Lady Mae Alabanza
- Department of Small Molecule Process Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Sean M. Kelly
- Department of Small Molecule Process Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Douglas L. Orsi
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Francis Gosselin
- Department of Small Molecule Process Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Ryan A. Altman
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
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26
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Altman RA. In This Issue, Volume 10, Issue 6. ACS Med Chem Lett 2019. [DOI: 10.1021/acsmedchemlett.9b00234] [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: 11/30/2022] Open
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27
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Vallakati R, Plotnikov AT, Altman RA. Synthesis of 2-D- L-Tryptophan by Sequential Ir-Catalyzed Reactions. Tetrahedron 2019; 75:2261-2264. [PMID: 31130755 DOI: 10.1016/j.tet.2019.02.054] [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: 11/28/2022]
Abstract
Herein, we report a practical synthesis of 2-D-L-tryptophan via sequential Ir-catalyzed C-H borylation, and Ir-catalyzed C-2-deborylative deuteration steps. In this synthetic sequence, deprotection of the Boc and methyl ester groups proved challenging, due to replacement of deuterium with hydrogen. However, mild deprotection conditions were developed to avoid this D/H scrambling. Further, 2-D-L-Tryptophan is stable in many buffers used for biological studies.
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Affiliation(s)
- Ravikrishna Vallakati
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Abel T Plotnikov
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Ryan A Altman
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
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28
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Abstract
A new bench-stable trifluoromethylation reagent, phenyl bromodifluoroacetate, converts readily available alcohols to trifluoromethanes in a Cu-catalyzed deoxytrifluoromethylation reaction. This reaction streamlines access to target biologically active molecules, and should be useful for a variety of medicinal, agricultural, and materials chemists.
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Affiliation(s)
- Francisco de Azambuja
- Department of Medicinal Chemistry , The University of Kansas , Lawrence , Kansas 66045 , United States
| | - Sydney M Lovrien
- Department of Medicinal Chemistry , The University of Kansas , Lawrence , Kansas 66045 , United States
| | - Patrick Ross
- Department of Medicinal Chemistry , The University of Kansas , Lawrence , Kansas 66045 , United States
| | - Brett R Ambler
- Department of Medicinal Chemistry , The University of Kansas , Lawrence , Kansas 66045 , United States
| | - Ryan A Altman
- Department of Medicinal Chemistry , The University of Kansas , Lawrence , Kansas 66045 , United States
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29
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Altman RA, Sharma KK, Rajewski LG, Toren PC, Baltezor MJ, Pal M, Karad SN. Tyr 1-ψ[( Z)CF═CH]-Gly 2 Fluorinated Peptidomimetic Improves Distribution and Metabolism Properties of Leu-Enkephalin. ACS Chem Neurosci 2018; 9:1735-1742. [PMID: 29648788 DOI: 10.1021/acschemneuro.8b00085] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [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: 12/17/2022] Open
Abstract
Opioid peptides are key regulators in cellular and intercellular physiological responses, and could be therapeutically useful for modulating several pathological conditions. Unfortunately, the use of peptide-based agonists to target centrally located opioid receptors is limited by poor physicochemical (PC), distribution, metabolic, and pharmacokinetic (DMPK) properties that restrict penetration across the blood-brain barrier via passive diffusion. To address these problems, the present paper exploits fluorinated peptidomimetics to simultaneously modify PC and DMPK properties, thus facilitating entry into the central nervous system. As an initial example, the present paper exploited the Tyr1-ψ[( Z)CF═CH]-Gly2 peptidomimetic to improve PC druglike characteristics (computational), plasma and microsomal degradation, and systemic and CNS distribution of Leu-enkephalin (Tyr-Gly-Gly-Phe-Leu). Thus, the fluoroalkene replacement transformed an instable in vitro tool compound into a stable and centrally distributed in vivo probe. In contrast, the Tyr1-ψ[CF3CH2-NH]-Gly2 peptidomimetic decreased stability by accelerating proteolysis at the Gly3-Phe4 position.
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Affiliation(s)
- Ryan A. Altman
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Krishna K. Sharma
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Lian G. Rajewski
- Biotechnology Innovation and Optimization Center, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Paul C. Toren
- Biotechnology Innovation and Optimization Center, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Michael J. Baltezor
- Biotechnology Innovation and Optimization Center, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Mohan Pal
- Department of Pathology, Michigan Medicine, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Somnath N. Karad
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
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30
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Shin I, Ambler BR, Wherritt D, Griffith WP, Maldonado AC, Altman RA, Liu A. Stepwise O-Atom Transfer in Heme-Based Tryptophan Dioxygenase: Role of Substrate Ammonium in Epoxide Ring Opening. J Am Chem Soc 2018; 140:4372-4379. [PMID: 29506384 PMCID: PMC5874177 DOI: 10.1021/jacs.8b00262] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [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: 12/19/2022]
Abstract
Heme-based tryptophan dioxygenases are established immunosuppressive metalloproteins with significant biomedical interest. Here, we synthesized two mechanistic probes to specifically test if the α-amino group of the substrate directly participates in a critical step of the O atom transfer during catalysis in human tryptophan 2,3-dioxygenase (TDO). Substitution of the nitrogen atom of the substrate to a carbon (probe 1) or oxygen (probe 2) slowed the catalytic step following the first O atom transfer such that transferring the second O atom becomes less likely to occur, although the dioxygenated products were observed with both probes. A monooxygenated product was also produced from probe 2 in a significant quantity. Analysis of this new product by HPLC coupled UV-vis spectroscopy, high-resolution mass spectrometry, 1H NMR, 13C NMR, HSQC, HMBC, and infrared (IR) spectroscopies concluded that this monooxygenated product is a furoindoline compound derived from an unstable epoxyindole intermediate. These results prove that small molecules can manipulate the stepwise O atom transfer reaction of TDO and provide a showcase for a tunable mechanism by synthetic compounds. The product analysis results corroborate the presence of a substrate-based epoxyindole intermediate during catalysis and provide the first substantial experimental evidence for the involvement of the substrate α-amino group in the epoxide ring-opening step during catalysis. This combined synthetic, biochemical, and biophysical study establishes the catalytic role of the α-amino group of the substrate during the O atom transfer reactions and thus represents a substantial advance to the mechanistic comprehension of the heme-based tryptophan dioxygenases.
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Affiliation(s)
- Inchul Shin
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Brett R. Ambler
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Daniel Wherritt
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Wendell P. Griffith
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Amanda C. Maldonado
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Ryan A. Altman
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Aimin Liu
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
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31
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Abstract
Fluorination of organic molecules significantly impacts the basic physicochemical properties of small and large biologically active molecules, agrichemicals, and materials. Thus, the development of synthetic reactions to access these substructures is important for many applied fields of chemistry. However, these fluorine-induced perturbations of chemical properties can inhibit standard chemical transformations, which provides unique challenges for synthetic organic chemists. In addition, the physicochemical properties imparted by fluorinated substituents can enable distinct reactivity patterns relative to non-fluorinated substrates, thus making synthetic organofluorine chemistry a fertile ground for developing new, exciting transformations. In this feature article, we detail our experiences in methodology, wherein fluorinated substrates have enabled unique reactivity patterns relative to non-fluorous substrates. Specifically, we highlight the non-standard chemo- and regio-selectivities imparted by fluorinated substrates on Pd-catalyzed coupling reactions, nucleophilic addition reactions of olefins, and Cu-catalyzed decarboxylative fluoroalkylation reactions.
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Affiliation(s)
- Douglas L Orsi
- Department of Medicinal Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, USA.
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32
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Karad SN, Pal M, Crowley RS, Prisinzano TE, Altman RA. Synthesis and Opioid Activity of Tyr 1 -ψ[(Z)CF=CH]-Gly 2 and Tyr 1 -ψ[(S)/(R)-CF 3 CH-NH]-Gly 2 Leu-enkephalin Fluorinated Peptidomimetics. ChemMedChem 2017; 12:571-576. [PMID: 28296145 DOI: 10.1002/cmdc.201700103] [Citation(s) in RCA: 21] [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: 02/15/2017] [Revised: 03/13/2017] [Indexed: 12/16/2022]
Abstract
We describe the design, synthesis, and opioid activity of fluoroalkene (Tyr1 -ψ[(Z)CF=CH]-Gly2 ) and trifluoroethylamine (Tyr1 -ψ[(S)/(R)-CF3 CH-NH]-Gly2 ) analogues of the endogenous opioid neuropeptide, Leu-enkephalin. The fluoroalkene peptidomimetic exhibited low nanomolar functional activity (5.0±2 nm and 60±15 nm for δ- and μ-opioid receptors, respectively) with a μ/δ-selectivity ratio that mimics that of the natural peptide. However, the trifluoroethylamine peptidomimetics, irrespective of stereochemistry, did not activate the opioid receptors, which suggest that bulky CF3 substituents are not tolerated at this position.
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Affiliation(s)
- Somnath Narayan Karad
- Department of Medicinal Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas, 66045, USA
| | - Mohan Pal
- Department of Medicinal Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas, 66045, USA
| | - Rachel S Crowley
- Department of Medicinal Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas, 66045, USA
| | - Thomas E Prisinzano
- Department of Medicinal Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas, 66045, USA
| | - Ryan A Altman
- Department of Medicinal Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas, 66045, USA
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33
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Abstract
A nucleophilic addition reaction of aryl thiols to readily available β,β-difluorostyrenes provides α,α-difluoroalkylthioethers. The reaction proceeds through an unstable anionic intermediate, prone to eliminate fluoride and generate α-fluorovinylthioethers. However, the use of base catalysis overcomes the facile β-fluoride elimination, generating α,α-difluoroalkylthioethers in excellent yields and selectivities.
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Affiliation(s)
- Douglas L Orsi
- Department of Medicinal Chemistry, The University of Kansas , 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, United States
| | - Brandon J Easley
- Department of Medicinal Chemistry, The University of Kansas , 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, United States
| | - Ashley M Lick
- Department of Medicinal Chemistry, The University of Kansas , 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, United States
| | - Ryan A Altman
- Department of Medicinal Chemistry, The University of Kansas , 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, United States
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34
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Affiliation(s)
- Ming‐Hsiu Yang
- Department of Medicinal Chemistry The University of Kansas 1251 Wescoe Hall Drive Lawrence KS 66045 USA
| | - Jordan R. Hunt
- Department of Medicinal Chemistry The University of Kansas 1251 Wescoe Hall Drive Lawrence KS 66045 USA
| | - Niusha Sharifi
- Department of Medicinal Chemistry, Faculty of Pharmacy Tehran University of Medical Science 16 Azar St. Tehran 1417614411 Iran
| | - Ryan A. Altman
- Department of Medicinal Chemistry The University of Kansas 1251 Wescoe Hall Drive Lawrence KS 66045 USA
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35
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Yang MH, Hunt JR, Sharifi N, Altman RA. Palladium Catalysis Enables Benzylation of α,α-Difluoroketone Enolates. Angew Chem Int Ed Engl 2016; 55:9080-3. [PMID: 27312868 DOI: 10.1002/anie.201604149] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [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: 04/28/2016] [Indexed: 11/06/2022]
Abstract
A palladium-catalyzed decarboxylative benzylation reaction of α,α-difluoroketone enolates is reported, in which the key C(α)-C(sp(3) ) bond is generated by reductive elimination from a palladium intermediate. The transformation provides convergent access to α-benzyl-α,α-difluoroketone-based products, and should be useful for accessing biological probes.
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Affiliation(s)
- Ming-Hsiu Yang
- Department of Medicinal Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS, 66045, USA
| | - Jordan R Hunt
- Department of Medicinal Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS, 66045, USA
| | - Niusha Sharifi
- Department of Medicinal Chemistry, Faculty of Pharmacy, Tehran University of Medical Science, 16 Azar St., Tehran, 1417614411, Iran
| | - Ryan A Altman
- Department of Medicinal Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS, 66045, USA.
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36
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Abstract
Trifluoroethylarenes are found in a variety of biologically active molecules, and strategies for accessing this substructure are important for developing therapeutic candidates and biological probes. Trifluoroethylarenes can be directly accessed via nucleophilic trifluoromethylation of benzylic electrophiles; however, current catalytic methods do not effectively transform electron-deficient substrates and heterocycles. To address this gap, we report a Cu-catalyzed decarboxylative trifluoromethylation of benzylic bromodifluoroacetates. To account for the tolerance of sensitive functional groups, we propose an inner-sphere mechanism of decarboxylation.
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Affiliation(s)
- Brett R Ambler
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Lingui Zhu
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Ryan A Altman
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
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37
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Abstract
"Cu-CF3" species have been used historically for a broad spectrum of nucleophilic trifluoromethylation reactions. Although recent advancements have employed ligands to stabilize and harness the reactivity of this key organometallic intermediate, the ability of a ligand to differentiate a regiochemical outcome of a Cu-CF3-mediated or -catalyzed reaction has not been previously reported. Herein, we report the first example of a Cu-catalyzed trifluoromethylation reaction in which a ligand controls the regiochemical outcome. More specifically, we demonstrate the ability of bipyridyl-derived ligands to control the regioselectivity of the Cu-catalyzed nucleophilic trifluoromethylation reactions of propargyl electrophiles to generate (trifluoromethyl)allenes. This method provides a variety of di-, tri-, and tetrasubstituted (trifluoromethyl)allenes, which can be further modified to generate complex fluorinated substructures.
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Affiliation(s)
- Brett R Ambler
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Santosh Peddi
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Ryan A Altman
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
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38
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Yang M, Orsi DL, Altman RA. Ligand-controlled regiodivergent palladium-catalyzed decarboxylative allylation reaction to access α,α-difluoroketones. Angew Chem Int Ed Engl 2015; 54:2361-5. [PMID: 25581845 PMCID: PMC4373536 DOI: 10.1002/anie.201410039] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [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: 10/13/2014] [Revised: 11/25/2014] [Indexed: 11/08/2022]
Abstract
α,α-Difluoroketones possess unique physicochemical properties that are useful for developing therapeutics and probes for chemical biology. To access the α-allyl-α,α-difluoroketone substructure, complementary palladium-catalyzed decarboxylative allylation reactions were developed to provide linear and branched α-allyl-α,α-difluoroketones. For these orthogonal processes, the fluorination pattern of the substrate enabled the ligands to dictate the regioselectivity of the transformations.
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Affiliation(s)
- Ming–Hsiu Yang
- Department of Medicinal Chemistry, the University of Kansas 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, United States
| | - Douglas L. Orsi
- Department of Medicinal Chemistry, the University of Kansas 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, United States
| | - Ryan A. Altman
- Department of Medicinal Chemistry, the University of Kansas 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, United States
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39
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Yang MH, Orsi DL, Altman RA. Ligand-Controlled Regiodivergent Palladium-Catalyzed Decarboxylative Allylation Reaction to Access α,α-Difluoroketones. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201410039] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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40
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Abstract
The ability to convert simple and common substrates into fluoroalkyl derivatives under mild conditions remains an important goal for medicinal and agricultural chemists. One representative example of a desirable transformation involves the conversion of aromatic and heteroaromatic ketones and aldehydes into aryl and heteroaryl β,β,β-trifluoroethylarenes and -heteroarenes. The traditional approach for this net transformation involves stoichiometric metals and/or multistep reaction sequences that consume excessive time, material, and labor resources while providing low yields of products. To complement these traditional strategies, we report a one-pot metal-free decarboxylative procedure for accessing β,β,β-trifluoroethylarenes and -heteroarenes from readily available ketones and aldehydes. This method features several benefits, including ease of operation, readily available reagents, mild reaction conditions, high functional-group compatibility, and scalability.
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Affiliation(s)
- Yupu Qiao
- Department of Medicinal Chemistry, The University of Kansas , Lawrence, Kansas 66045, United States
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41
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Abstract
The development of efficient methods for accessing fluorinated functional groups is desirable. Herein, we report a two-step method that utilizes catalytic Cu for the decarboxylative trifluoromethylation of propargyl bromodifluoroacetates. This protocol affords a mixture of propargyl trifluoromethanes and trifluoromethyl allenes.
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Affiliation(s)
- Brett R Ambler
- Department of Medicinal Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, United States
| | - Santosh Peddi
- Department of Pharmacy, Birla Institute of Technology & Science, Pilani - Hyderabad Campus, Jawahar Nagar, Shameerpet Mandal, Hyderabad, 500078 Andhra Pradesh, India
| | - Ryan A Altman
- Department of Medicinal Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, United States
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42
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Affiliation(s)
- Ryan A Altman
- Department of Medicinal Chemistry The University of Kansas 1251 Wescoe Hall Drive 4046A Malott Hall Lawrence, KS 66045 USA.
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43
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Abstract
The development of new synthetic fluorination reactions has important implications in medicinal, agricultural, and materials chemistries. Given the prevalence and accessibility of alcohols, methods to convert alcohols to trifluoromethanes are desirable. However, this transformation typically requires four-step processes, specialty chemicals, and/or stoichiometric metals to access the trifluoromethyl-containing product. A two-step copper-catalyzed decarboxylative protocol for converting allylic alcohols to trifluoromethanes is reported. Preliminary mechanistic studies distinguish this reaction from previously reported Cu-mediated reactions.
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Affiliation(s)
- Brett R Ambler
- Department of Medicinal Chemistry, University of Kansas , 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, United States
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44
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Zhu L, Liu S, Douglas JT, Altman RA. Copper-mediated deoxygenative trifluoromethylation of benzylic xanthates: generation of a C-CF(3) bond from an O-based electrophile. Chemistry 2013; 19:12800-5. [PMID: 23922222 DOI: 10.1002/chem.201302328] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [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: 06/18/2013] [Indexed: 11/09/2022]
Abstract
The conversion of an alcohol-based functional group, into a trifluoromethyl analogue is a desirable transformation. However, few methods are capable of converting O-based electrophiles into trifluoromethanes. The copper-mediated trifluoromethylation of benzylic xanthates using Umemoto's reagent as the source of CF3 to form C-CF3 bonds is described. The method is compatible with an array of benzylic xanthates bearing useful functional groups. A preliminary mechanistic investigation suggests that the C-CF3 bond forms by reaction of the substrate with in situ generated CuCF3 and CuOTf. Further evidence suggests that the reaction could proceed via a radical cation intermediate.
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Affiliation(s)
- Lingui Zhu
- Department of Medicinal Chemistry, University of Kansas, Lawrence, KS 66045 (USA), Fax: (+1) 785-864-5326
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45
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Yang MH, Matikonda SS, Altman RA. Preparation of Fluoroalkenes via the Shapiro Reaction: Direct Access to Fluorinated Peptidomimetics. Org Lett 2013; 15:3894-7. [DOI: 10.1021/ol401637n] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Ming-Hsiu Yang
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Siddharth S. Matikonda
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
| | - Ryan A. Altman
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, Kansas 66045, United States
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46
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Abstract
The first total syntheses of the Lycopodium alkaloids (+)-nankakurine A (2), (+)-nankakurine B (3), and the originally purported structure 1 of nankakurine A were accomplished. The syntheses of 2 and 3 feature a demanding intramolecular azomethine imine cycloaddition as the key step for generating the octahydro-3,5-ethanoquinoline moiety and installing the correct relative configuration at the spiropiperidine ring juncture. The cyclization precursor was prepared from octahydronaphthalene ketone 50, which was assembled from enone (+)-9 and diene 48 by a cationic Diels-Alder reaction. The Diels-Alder reactants were synthesized from 5-hexyn-1-ol (16) and (+)-pulegone (49), respectively. The tetracyclic ring system of 1 was generated using an unprecedented nitrogen-terminated aza-Prins cyclization cascade. The enantioselective total syntheses of (+)-nankakurine A (2) and (+)-nankakurine B (3) establish the relative and absolute configuration of these alkaloids and are sufficiently concise that substantial quantities of 2 and 3 were prepared for biological studies. (+)-Nankakurine A and (+)-nankakurine B showed no effect on neurite outgrowth in rat hippocampal H-19 cells over a concentration range of 0.3-10 μM.
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Affiliation(s)
- Ryan A. Altman
- Department of Chemistry, 1102 Natural Sciences II, University of California, Irvine, Irvine, CA 92697-2025
| | - Bradley L. Nilsson
- Department of Chemistry, 1102 Natural Sciences II, University of California, Irvine, Irvine, CA 92697-2025
| | - Larry E. Overman
- Department of Chemistry, 1102 Natural Sciences II, University of California, Irvine, Irvine, CA 92697-2025
| | - Javier Read de Alaniz
- Department of Chemistry, 1102 Natural Sciences II, University of California, Irvine, Irvine, CA 92697-2025
| | - Jason M. Rohde
- Department of Chemistry, 1102 Natural Sciences II, University of California, Irvine, Irvine, CA 92697-2025
| | - Veronique Taupin
- Aging Department, sanofi-aventis R&D, 1 Avenue Pierre Brossolette, 91385 Chilly-Mazarin, France
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47
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Taylor AM, Altman RA, Buchwald SL. Palladium-catalyzed enantioselective alpha-arylation and alpha-vinylation of oxindoles facilitated by an axially chiral P-stereogenic ligand. J Am Chem Soc 2009; 131:9900-1. [PMID: 19580273 DOI: 10.1021/ja903880q] [Citation(s) in RCA: 227] [Impact Index Per Article: 15.1] [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
The enantioselective alpha-arylation and alpha-vinylation of oxindoles catalyzed by Pd and a biarylmonophosphine ligand with both axial and phosphorus-based chirogenicity is reported. The resultant quaternary carbon stereocenters are formed in high enantiomeric excess, and the conditions tolerate a range of substitution on both the oxindole and the aryl/vinyl coupling partners.
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Affiliation(s)
- Alexander M Taylor
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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48
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Abstract
In the cross-coupling reactions of unprotected oxindoles with aryl halides, Pd- and Cu-based catalyst systems displayed orthogonal chemoselectivity. A Pd-dialkylbiarylphosphine-based catalyst system chemoselectively arylated oxindole at the 3 position, while arylation occurred exclusively at the nitrogen using a Cu-diamine-based catalyst system. Computational examination of the relevant L1Pd(Ar)(oxindolate) and diamine-Cu(oxindolate) species was performed to gain mechanistic insight into the controlling features of the observed chemoselectivity.
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Affiliation(s)
- Ryan A. Altman
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Alan M. Hyde
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Xiaohua Huang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Stephen L. Buchwald
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
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49
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Abstract
Pyrrole 2-carboxylic acid (L5) was found to be an effective ligand for the Cu-catalyzed monoarylation of anilines with aryl iodides and bromides. Under the reported conditions (10% CuI/20% L5/DMSO/K3PO 4/80-100 degrees C/20-24 h), a variety of useful functional groups were tolerated, and moderate to good yields of the diaryl amine products were obtained.
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Affiliation(s)
- Ryan A. Altman
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Kevin W. Anderson
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Stephen L. Buchwald
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139
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50
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Abstract
The following protocol describes the selective cross-coupling of an amine with an aryl halide using a Pd-based catalyst to provide the corresponding N-arylated amine. This general procedure for C-N bond formation includes a detailed description of an appropriate reaction setup, two methods for assaying the crude reaction mixtures (thin layer chromatography (TLC) and gas chromatography (GC)) and procedures for the isolation, purification and characterization of the anticipated product. Reagents and catalyst precursors can be manipulated in the air; however, the cross-coupling reactions must be performed under an inert atmosphere. Two Pd-catalyzed C-N bond-forming reactions are included in the text as representative examples of these procedures. Although the reactions can proceed in <5 min, the protocols, including workup, generally take 6-30 h to complete.
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Affiliation(s)
- Ryan A Altman
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue 18-490, Cambridge, Massachusetts 02139, USA
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