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Liu M, Uyeda C. Redox Approaches to Carbene Generation in Catalytic Cyclopropanation Reactions. Angew Chem Int Ed Engl 2024; 63:e202406218. [PMID: 38752878 DOI: 10.1002/anie.202406218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Indexed: 06/15/2024]
Abstract
Transition metal-catalyzed carbene transfer reactions have a century-old history in organic chemistry and are a primary method for the synthesis of cyclopropanes. Much of the work in this field has focused on the use of diazo compounds and related precursors, which can transfer a carbene fragment to a catalyst with concomitant loss of a stable byproduct. Despite the utility of this approach, there are persistent limitations in the scope of viable carbenes, most notably those lacking stabilizing substituents. By coupling carbene transfer chemistry with two-electron redox cycles, it is possible to expand the available starting materials that can be used as carbene precursors. In this Minireview, we discuss emerging catalytic reductive cyclopropanation reactions using either gem-dihaloalkanes or carbonyl compounds. This strategy is inspired by classic stoichiometric transformations, such as the Simmons-Smith cyclopropanation and the Clemmensen reduction, but instead entails the formation of a catalytically generated transition metal carbene or carbenoid. We also present recent efforts to generate carbenes directly from methylene (CR2H2) groups via a formal 1,1-dehydrogenation. These reactions are currently restricted to substrates containing electron-withdrawing substituents, which serve to facilitate deprotonation and subsequent oxidation of the anion.
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Affiliation(s)
- Mingxin Liu
- Department of Chemistry, Purdue University, 560 Oval Dr., West Lafayette, IN 47907, USA
| | - Christopher Uyeda
- Department of Chemistry, Purdue University, 560 Oval Dr., West Lafayette, IN 47907, USA
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Hu J, Tang M, Wang J, Wu Z, Friedrich A, Marder TB. Photocatalyzed Borylcyclopropanation of Alkenes with a (Diborylmethyl)iodide Reagent. Angew Chem Int Ed Engl 2023; 62:e202305175. [PMID: 37527975 DOI: 10.1002/anie.202305175] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 07/31/2023] [Accepted: 08/01/2023] [Indexed: 08/03/2023]
Abstract
Cyclopropane skeletons play a prominent role in the development of organic synthesis and pharmaceutical chemistry. Herein, we report the design and synthesis of a stable, multifunctional (diborylmethyl)iodide reagent (CHI(Bpin)2 ) for the photoinduced cyclopropanation of alkenes, providing an array of 1,2-substituted cyclopropylboronates in good yields. This α-haloboronic ester can be readily synthesized on a multigram scale from commercially available starting materials. Furthermore, the protocol displays high chemo- and diastereoselectivity, excellent functional-group tolerance, and allows for late-stage borylcyclopropanation of complex molecules. Mechanistic studies reveal that the borylcyclopropanation proceeds through a radical addition/polar cyclization pathway mediated by the photocatalyst fac-Ir(ppy)3 and visible light.
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Affiliation(s)
- Jiefeng Hu
- School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, 211816 Jiangsu, China
- Institut für Anorganische Chemie and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg Am Hubland, 97074, Würzburg, Germany
| | - Man Tang
- School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, 211816 Jiangsu, China
| | - Jing Wang
- School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, 211816 Jiangsu, China
| | - Zhu Wu
- Institut für Anorganische Chemie and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg Am Hubland, 97074, Würzburg, Germany
| | - Alexandra Friedrich
- Institut für Anorganische Chemie and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg Am Hubland, 97074, Würzburg, Germany
| | - Todd B Marder
- Institut für Anorganische Chemie and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg Am Hubland, 97074, Würzburg, Germany
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Poudel DP, Pokhrel A, Tak RK, Shankar M, Giri R. Photosensitized O 2 enables intermolecular alkene cyclopropanation by active methylene compounds. Science 2023; 381:545-553. [PMID: 37535731 PMCID: PMC11216814 DOI: 10.1126/science.adg3209] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 06/26/2023] [Indexed: 08/05/2023]
Abstract
Cyclopropanes are key features in many preclinical, clinical, and commercial drugs, as well as natural products. The most prolific technique for their synthesis is the metal-catalyzed reaction of an alkene with a diazoalkane, a highly energetic reagent requiring stringent safety precautions. Discovery of alternative innocuous reagents remains an ongoing challenge. Herein, we report a simple photoredox-catalyzed intermolecular cyclopropanation of unactivated alkenes with active methylene compounds. The reaction proceeds in neutral solvent under air or dioxygen (O2) with a photoredox catalyst excited by blue light-emitting diode light and an iodine co-catalyst that is either added as molecular iodine or generated in situ from alkyl iodides. Mechanistic investigations indicate that photosensitized O2 plays a vital role in the generation of carbon-centered radicals for both the addition of active methylene compounds to alkenes and the ring closure.
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Affiliation(s)
- Dhruba P. Poudel
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
| | | | | | - Majji Shankar
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Ramesh Giri
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
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Ni J, Xia X, Gu D, Wang Z. Ti-Catalyzed Modular Ketone Synthesis from Carboxylic Derivatives and gem-Dihaloalkanes. J Am Chem Soc 2023. [PMID: 37365677 DOI: 10.1021/jacs.3c04009] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
Ketones are ubiquitous in organic synthesis. However, the general method to convert widely available carboxylic acids, unactivated esters, and amides into ketones remains elusive. Herein, we describe the Ti-catalyzed modular ketone synthesis from carboxylic derivatives and easily accessed gem-dihaloalkanes. Notably, this protocol could achieve the direct catalytic olefination of carboxylic acids. This method features a sequence of olefination and electrophilic transformation and good functional group compatibility and allows rapid access to various functionalized ketones. Preliminary mechanistic studies provide insights into the reaction pathway and support the intermediacy of plausible alkylidene titanocene and gem-bimetallic complexes.
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Affiliation(s)
- Jiabin Ni
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, School of Science, Westlake University, Hangzhou 310024, Zhejiang Province, China; Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou 310024, Zhejiang Province, China
| | - Xiaowen Xia
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, School of Science, Westlake University, Hangzhou 310024, Zhejiang Province, China; Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou 310024, Zhejiang Province, China
| | - Danyu Gu
- Instrumentation and Service Center for Molecular Sciences, Westlake University, Hangzhou 310024, Zhejiang Province, China
| | - Zhaobin Wang
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, School of Science, Westlake University, Hangzhou 310024, Zhejiang Province, China; Institute of Natural Sciences, Westlake Institute for Advanced Study, Hangzhou 310024, Zhejiang Province, China
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Williams OP, Chmiel AF, Mikhael M, Bates DM, Yeung CS, Wickens ZK. Practical and General Alcohol Deoxygenation Protocol. Angew Chem Int Ed Engl 2023; 62:e202300178. [PMID: 36840940 PMCID: PMC10121858 DOI: 10.1002/anie.202300178] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 02/23/2023] [Accepted: 02/23/2023] [Indexed: 02/26/2023]
Abstract
Herein, we describe a practical protocol for the removal of alcohol functional groups through reductive cleavage of their benzoate ester analogs. This transformation requires a strong single electron transfer (SET) reductant and a means to accelerate slow fragmentation following substrate reduction. To accomplish this, we developed a photocatalytic system that generates a potent reductant from formate salts alongside Brønsted or Lewis acids that promote fragmentation of the reduced intermediate. This deoxygenation procedure is effective across structurally and electronically diverse alcohols and enables a variety of difficult net transformations. This protocol requires no precautions to exclude air or moisture and remains efficient on multigram scale. Finally, the system can be adapted to a one-pot benzoylation-deoxygenation sequence to enable direct alcohol deletion. Mechanistic studies validate that the role of acidic additives is to promote the key C(sp3 )-O bond fragmentation step.
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Affiliation(s)
- Oliver P. Williams
- Department of Chemistry, University of Wisconsin-Madison; Madison, Wisconsin, 53706, United States
| | - Alyah F. Chmiel
- Department of Chemistry, University of Wisconsin-Madison; Madison, Wisconsin, 53706, United States
| | - Myriam Mikhael
- Discovery Chemistry, Merck & Co., Inc., 33 Avenue Louis Pasteur, Boston, MA 02115, United States
| | - Desiree M. Bates
- Department of Chemistry, University of Wisconsin-Madison; Madison, Wisconsin, 53706, United States
| | - Charles S. Yeung
- Discovery Chemistry, Merck & Co., Inc., 33 Avenue Louis Pasteur, Boston, MA 02115, United States
| | - Zachary K. Wickens
- Department of Chemistry, University of Wisconsin-Madison; Madison, Wisconsin, 53706, United States
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An unexpected reaction of indole derivatives and EAA catalyzed with InCl3. MOLECULAR CATALYSIS 2023. [DOI: 10.1016/j.mcat.2023.113065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
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Palomo E, Sharma AK, Wang Z, Jiang L, Maseras F, Suero MG. Generating Fischer-Type Rh-Carbenes with Rh-Carbynoids. J Am Chem Soc 2023; 145:4975-4981. [PMID: 36812070 PMCID: PMC9999426 DOI: 10.1021/jacs.3c00012] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
We describe the first catalytic generation of Fischer-type acyloxy Rh(II)-carbenes from carboxylic acids and Rh(II)-carbynoids. This novel class of transient donor/acceptor Rh(II)-carbenes evolved through a cyclopropanation process providing access to densely functionalized cyclopropyl-fused lactones with excellent diastereoselectivity. DFT calculations allowed the analysis of the properties of Rh(II)-carbynoids and acyloxy Rh(II)-carbenes as well as the characterization of the mechanism.
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Affiliation(s)
- Eric Palomo
- Institute of Chemical Research of Catalonia (ICIQ-CERCA), The Barcelona Institute of Science and Technology, Països Catalans 16, 43007 Tarragona, Spain.,Departament de Química Analítica i Química Orgánica, Universitat Rovira i Virgili, Calle Marcel.lí Domingo, 1, Tarragona 43007, Spain
| | - Akhilesh K Sharma
- Institute of Chemical Research of Catalonia (ICIQ-CERCA), The Barcelona Institute of Science and Technology, Països Catalans 16, 43007 Tarragona, Spain
| | - Zhaofeng Wang
- Institute of Chemical Research of Catalonia (ICIQ-CERCA), The Barcelona Institute of Science and Technology, Països Catalans 16, 43007 Tarragona, Spain
| | - Liyin Jiang
- Institute of Chemical Research of Catalonia (ICIQ-CERCA), The Barcelona Institute of Science and Technology, Països Catalans 16, 43007 Tarragona, Spain
| | - Feliu Maseras
- Institute of Chemical Research of Catalonia (ICIQ-CERCA), The Barcelona Institute of Science and Technology, Països Catalans 16, 43007 Tarragona, Spain
| | - Marcos G Suero
- Institute of Chemical Research of Catalonia (ICIQ-CERCA), The Barcelona Institute of Science and Technology, Països Catalans 16, 43007 Tarragona, Spain
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Gao Q, Xu S. Site- and Stereoselective C(sp 3 )-H Borylation of Strained (Hetero)Cycloalkanols Enabled by Iridium Catalysis. Angew Chem Int Ed Engl 2023; 62:e202218025. [PMID: 36581587 DOI: 10.1002/anie.202218025] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 12/28/2022] [Accepted: 12/29/2022] [Indexed: 12/31/2022]
Abstract
Transition metal-catalyzed site- and stereoselective C-H activation of strained (hetero)cycloalkanes remains a formidable challenge. We herein report a carbamate-directed iridium-catalyzed asymmetric β-C(sp3 )-H borylation of cyclopropanol derivatives. A variety of densely functionalized cyclopropanols were obtained in good enantioselectivities via desymmetrization and kinetic resolution. In addition, site-selective C(sp3 )-H borylation of methine groups furnished α-borylated (hetero)cycloalkanols in moderate to good yields. The synthetic utility of the method was further shown in a gram-scale synthesis and diverse downstream transformations of borylated products.
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Affiliation(s)
- Qian Gao
- State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Senmiao Xu
- State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
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