1
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Ai CR, Liu L, Wang XC. Borane-Catalyzed Enantioselective α-Alkylation of Unactivated 2-Alkylbenzoxazoles with Electron-Deficient Olefins. J Am Chem Soc 2024; 146:24663-24669. [PMID: 39163278 DOI: 10.1021/jacs.4c09067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/22/2024]
Abstract
Chiral borane-catalyzed reactions have recently emerged as a powerful tool for the enantioselective production of chiral scaffolds. In this study, we demonstrated for the first time that a chiral bisborane catalyst can be used for the α-functionalization of 2-alkylazaarenes; specifically, we accomplished unprecedented highly enantioselective α-alkylation of unactivated 2-alkylbenzoxazoles with electron-deficient olefins. The strong Lewis acidity and the steric bulk of the bisborane catalyst were essential to the observed reactivity and selectivity.
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Affiliation(s)
- Chong-Ren Ai
- State Key Laboratory and Institute of Elemento-Organic Chemistry, Haihe Laboratory of Sustainable Chemical Transformations, Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Lu Liu
- State Key Laboratory and Institute of Elemento-Organic Chemistry, Haihe Laboratory of Sustainable Chemical Transformations, Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Xiao-Chen Wang
- State Key Laboratory and Institute of Elemento-Organic Chemistry, Haihe Laboratory of Sustainable Chemical Transformations, Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin 300071, China
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2
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Wu Q, Han J, Huang J, Zhang H, Ren M, Zhang X, Fu Z. Asymmetric synthesis of chiral pyrazolo[3,4- b]pyridin-6-ones under carbene catalysis. Org Biomol Chem 2023; 21:6898-6902. [PMID: 37581413 DOI: 10.1039/d3ob01057k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
A structurally diverse set of chiral pyrazolo[3,4-b]pyridin-6-ones was efficiently prepared in excellent yields with excellent enantioselectivities via N-heterocyclic carbene-catalyzed oxidative [3 + 3] annulation of enals with pyrazol-5-amines. The reaction features mild reaction conditions, a broad substrate scope, and easy scale-up.
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Affiliation(s)
- Qianqian Wu
- Institute of Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China.
| | - Jinna Han
- Institute of Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China.
| | - Jie Huang
- Institute of Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China.
| | - Hailong Zhang
- Institute of Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China.
| | - Min Ren
- Institute of Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China.
| | - Xiaoxiang Zhang
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, China
| | - Zhenqian Fu
- Institute of Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China.
- Ningbo Institute, Chongqing Technology Innovation Center, Frontiers Science Center for Flexible Electronics (FSCFE), Northwestern Polytechnical University, Xi'an 710072, China
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3
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Eckhardt P, Elliot Q, Alabugin IV, Opatz T. Two Paths to Oxidative C-H Amination Under Basic Conditions: A Theoretical Case Study Reveals Hidden Opportunities Provided by Electron Upconversion. Chemistry 2022; 28:e202201637. [PMID: 35880945 PMCID: PMC9804812 DOI: 10.1002/chem.202201637] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Indexed: 01/09/2023]
Abstract
Traditionally, cross-dehydrogenative coupling (CDC) leads to C-N bond formation under basic and oxidative conditions and is proposed to proceed via a two-electron bond formation mediated by carbenium ions. However, the formation of such high-energy intermediates is only possible in the presence of strong oxidants, which may lead to undesired side reactions and poor functional group tolerance. In this work we explore if oxidation under basic conditions allows the formation of three-electron bonds (resulting in "upconverted" highly-reducing radical-anions). The benefit of this "upconversion" process is in the ability to use milder oxidants (e. g., O2 ) and to avoid high-energy intermediates. Comparison of the two- and three-electron pathways using quantum mechanical calculations reveals that not only does the absence of a strong oxidant shut down two-electron pathways in favor of a three-electron path but, paradoxically, weaker oxidants react faster with the upconverted reductants by avoiding the inverted Marcus region for electron transfer.
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Affiliation(s)
- Paul Eckhardt
- Department of ChemistryJohannes Gutenberg University MainzDuesbergweg 10–1455128MainzGermany
| | - Quintin Elliot
- Department of Chemistry and BiochemistryFlorida State UniversityTallahasseeFlorida 32306USA
| | - Igor V. Alabugin
- Department of Chemistry and BiochemistryFlorida State UniversityTallahasseeFlorida 32306USA
| | - Till Opatz
- Department of ChemistryJohannes Gutenberg University MainzDuesbergweg 10–1455128MainzGermany
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4
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Liu XJ, Zhang WY, Zheng C, You SL. Iridium-Catalyzed Asymmetric Allylic Substitution of Methyl Azaarenes. Angew Chem Int Ed Engl 2022; 61:e202200164. [PMID: 35238122 DOI: 10.1002/anie.202200164] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Indexed: 12/11/2022]
Abstract
Herein, an Ir-catalyzed asymmetric allylic substitution reaction of methyl azaarenes is described. Azaarenes such as (benzo)thiazole, oxazole, benzoimidazole, pyridine, and (iso)quinoline are all tolerated. The corresponding chiral azaarene derivatives are obtained in good yields with high enantioselectivity (up to 96 % yield and 99 % ee). The utilization of the Knochel reagent TMPZnBr⋅LiBr warrants the in situ formation of benzylic nucleophiles without additional activating reagents. 1 H NMR studies suggested a two-fold function of the Knochel reagent in this reaction. The synthetic utility of this method has been showcased by a concise enantioselective synthesis of an allosteric protein kinase modulator.
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Affiliation(s)
- Xi-Jia Liu
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Lu, Shanghai, 200032, China
| | - Wen-Yun Zhang
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Lu, Shanghai, 200032, China
| | - Chao Zheng
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Lu, Shanghai, 200032, China
| | - Shu-Li You
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Lu, Shanghai, 200032, China
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5
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Liu XJ, Zhang WY, Zheng C, You SL. Iridium‐Catalyzed Asymmetric Allylic Substitution of Methyl Azaarenes. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202200164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Xi-Jia Liu
- Shanghai Institute of Organic Chemistry State Key Laboratory of Organometallic Chemistry CHINA
| | - Wen-Yun Zhang
- Shanghai Institute of Organic Chemistry State Key Laboratory of Organometallic Chemistry CHINA
| | - Chao Zheng
- Shanghai Institute of Organic Chemistry State Key Laboratory of Organometallic Chemistry CHINA
| | - Shu-Li You
- Shanghai Inst Org Chem State Key Lab Organometallic Chem 345 Lingling Lu 200032 Shanghai CHINA
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6
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Mondal S, Dumur F, Gigmes D, Sibi MP, Bertrand MP, Nechab M. Enantioselective Radical Reactions Using Chiral Catalysts. Chem Rev 2022; 122:5842-5976. [DOI: 10.1021/acs.chemrev.1c00582] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Shovan Mondal
- Department of Chemistry, Syamsundar College, Shyamsundar 713424, West Bengal, India
| | - Frédéric Dumur
- Aix Marseille Univ, CNRS, Institut de Chimie Radicalaire UMR 7273, F-13390e Marseille, France
| | - Didier Gigmes
- Aix Marseille Univ, CNRS, Institut de Chimie Radicalaire UMR 7273, F-13390e Marseille, France
| | - Mukund P. Sibi
- Department of Chemistry and Biochemistry North Dakota State University, Fargo, North Dakota 58108, United States
| | - Michèle P. Bertrand
- Aix Marseille Univ, CNRS, Institut de Chimie Radicalaire UMR 7273, F-13390e Marseille, France
| | - Malek Nechab
- Aix Marseille Univ, CNRS, Institut de Chimie Radicalaire UMR 7273, F-13390e Marseille, France
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7
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Chu Y, Hu F, Feng P, Hui XP. N-Heterocyclic Carbene-Catalyzed Enantioselective Dearomatizing Annulation of Benzoxazoles with Enals. Org Chem Front 2022. [DOI: 10.1039/d1qo01861b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The first N-heterocyclic carbene-catalyzed enantioselective dearomatizing annulation of benzoxazoles with α,β-unsaturated aldehydes has been achieved. The reaction was found to be compatible with a wide range of benzoxazoles and the...
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8
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Lin S, Cui J, Chen Y, Li Y. Copper-Catalyzed Direct Cycloaddition of Imidazoles and Alkenes to Trifluoromethylated Tricyclic Imidazoles. J Org Chem 2021; 86:15768-15776. [PMID: 34632765 DOI: 10.1021/acs.joc.1c01832] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
We reported herein a copper-catalyzed trifluoromethylarylated cycloaddition of imidazoles and olefins using CF3SO2Cl as the radical source to synthesize highly functionalized tricyclic imidazoles. This procedure exhibits a wide range of substrate scope with 25%-93% isolated yields (36 examples). Mechanistic studies were carried out to support a free trifluoromethyl radical pathway.
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Affiliation(s)
- Shengnan Lin
- Key Laboratory of Molecule Synthesis and Function Discovery, College of Chemistry, Fuzhou University, Fuzhou 350108, China
| | - Jianchao Cui
- Key Laboratory of Molecule Synthesis and Function Discovery, College of Chemistry, Fuzhou University, Fuzhou 350108, China
| | - Yu Chen
- Key Laboratory of Molecule Synthesis and Function Discovery, College of Chemistry, Fuzhou University, Fuzhou 350108, China
| | - Yi Li
- Key Laboratory of Molecule Synthesis and Function Discovery, College of Chemistry, Fuzhou University, Fuzhou 350108, China
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9
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Lin S, Chen Y, Luo X, Li Y. Sustainable Cascades to Difluoroalkylated Polycyclic Imidazoles. European J Org Chem 2021. [DOI: 10.1002/ejoc.202100868] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Sheng‐Nan Lin
- Key Laboratory of Medicinal Chemistry for Natural Resource Ministry of Education and Yunnan Province School of Chemical Science and Technology Yunnan University Kunming 650091 China
| | - Yu Chen
- Key Laboratory of Molecule Synthesis and Function Discovery (Fujian Province University) College of Chemistry Fuzhou University Fuzhou 350108 China
| | - Xiao‐Dong Luo
- Key Laboratory of Medicinal Chemistry for Natural Resource Ministry of Education and Yunnan Province School of Chemical Science and Technology Yunnan University Kunming 650091 China
| | - Yi Li
- Key Laboratory of Molecule Synthesis and Function Discovery (Fujian Province University) College of Chemistry Fuzhou University Fuzhou 350108 China
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10
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Pavithra T, Devi ES, Maheswari CU. Recent Advances in N‐Heterocyclic Carbene Catalyzed Oxidative Cyclization for the Formation of Heterocycles. ASIAN J ORG CHEM 2021. [DOI: 10.1002/ajoc.202100289] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- T. Pavithra
- Department of Chemistry, School of Chemical and Biotechnology SASTRA Deemed University Thanjavur 613401 India
| | - E. Sankari Devi
- Department of Chemistry, School of Chemical and Biotechnology SASTRA Deemed University Thanjavur 613401 India
| | - C. Uma Maheswari
- Department of Chemistry, School of Chemical and Biotechnology SASTRA Deemed University Thanjavur 613401 India
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11
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Jiang P, Guo J, Gong M, Zhou X, Cao W, Fu Z, Huang W. N-Heterocyclic carbene-catalyzed [3 + 3] annulation of bromoenals with 2-aminochromones to access chromeno[2,3- b]pyridinones. Org Biomol Chem 2021; 19:4882-4886. [PMID: 34013952 DOI: 10.1039/d1ob00720c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
N-Heterocyclic carbene-catalyzed [3 + 3] annulation of bromoenals with 2-aminochromones has been successfully developed. A structurally diverse set of chromeno[2,3-b]pyridinones was efficiently constructed in acceptable to excellent yields. The reaction features mild reaction conditions, a broad substrate scope, and easy scale-up.
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Affiliation(s)
- Pengrui Jiang
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China.
| | - Jingcheng Guo
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China.
| | - Minghua Gong
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China.
| | - Xiangui Zhou
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China.
| | - Wei Cao
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China.
| | - Zhenqian Fu
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China.
| | - Wei Huang
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211816, China.
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12
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Zhang M, Wang Y, Li SJ, Wang X, Shi Q, Li X, Qu LB, Wei D, Lan Y. Multiple Functional Organocatalyst-Promoted Inert C–C Activation: Mechanism and Origin of Selectivities. ACS Catal 2021. [DOI: 10.1021/acscatal.0c05511] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Min Zhang
- Green Catalysis Center and College of Chemistry, Zhengzhou University, Zhengzhou, Henan 450001, China
| | - Yang Wang
- Department of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002, China
| | - Shi-Jun Li
- Green Catalysis Center and College of Chemistry, Zhengzhou University, Zhengzhou, Henan 450001, China
| | - Xinghua Wang
- Green Catalysis Center and College of Chemistry, Zhengzhou University, Zhengzhou, Henan 450001, China
| | - Qianqian Shi
- Green Catalysis Center and College of Chemistry, Zhengzhou University, Zhengzhou, Henan 450001, China
| | - Xue Li
- Green Catalysis Center and College of Chemistry, Zhengzhou University, Zhengzhou, Henan 450001, China
| | - Ling-Bo Qu
- Green Catalysis Center and College of Chemistry, Zhengzhou University, Zhengzhou, Henan 450001, China
| | - Donghui Wei
- Green Catalysis Center and College of Chemistry, Zhengzhou University, Zhengzhou, Henan 450001, China
| | - Yu Lan
- Green Catalysis Center and College of Chemistry, Zhengzhou University, Zhengzhou, Henan 450001, China
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13
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Chen X, Wang H, Jin Z, Chi YR. N
‐Heterocyclic
Carbene Organocatalysis: Activation Modes and Typical Reactive Intermediates. CHINESE J CHEM 2020. [DOI: 10.1002/cjoc.202000107] [Citation(s) in RCA: 92] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Xingkuan Chen
- Department of Chemistry, Jinan University Guangzhou Guangdong 510632 China
| | - Hongling Wang
- Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Guizhou University Huaxi District Guiyang Guizhou 550025 China
| | - Zhichao Jin
- Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Guizhou University Huaxi District Guiyang Guizhou 550025 China
| | - Yonggui Robin Chi
- Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Guizhou University Huaxi District Guiyang Guizhou 550025 China
- Division of Chemistry & Biological Chemistry, School of Physical & Mathematical Sciences, Nanyang Technological University Singapore 637371 Singapore
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14
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Barik S, Shee S, Ghosh A, Biju AT. Catalytic, Enantioselective C2-Functionalization of 3-Aminobenzofurans Using N-Heterocyclic Carbenes. Org Lett 2020; 22:3865-3869. [DOI: 10.1021/acs.orglett.0c01112] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Shilpa Barik
- Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012, India
| | - Sayan Shee
- Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012, India
| | - Arghya Ghosh
- Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012, India
| | - Akkattu T. Biju
- Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012, India
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15
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Xie Y, Li L, Sun S, Wu Z, Lang M, Jiang D, Wang J. Enantioselective NHC-Catalyzed [3+3] Annulation of α-Bromoenals with 2-Aminobenzimidazoles. Org Lett 2020; 22:391-394. [PMID: 31913042 DOI: 10.1021/acs.orglett.9b04054] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A chiral carbene-catalyzed [3+3] annulation of α-bromoenals with 2-aminobenzimidazoles providing pyrimido[1,2-a]benzimidazoles has been described. This protocol features a broad scope and good functional group tolerance. Biological studies indicated that the formed pyrimido[1,2-a]benzimidazole exhibited moderate cytotoxic activity against tumor cells.
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Affiliation(s)
- Yangxi Xie
- School of Pharmaceutical Sciences , Tsinghua University , Beijing 100084 , China
| | - Luoyuan Li
- School of Pharmaceutical Sciences , Tsinghua University , Beijing 100084 , China
| | - Shaofa Sun
- College of Chemistry and Biological Sciences , Hubei University of Science and Technology , Hubei 437100 , China
| | - Zijun Wu
- School of Pharmaceutical Sciences , Tsinghua University , Beijing 100084 , China
| | - Ming Lang
- School of Pharmaceutical Sciences , Tsinghua University , Beijing 100084 , China
| | - Di Jiang
- School of Pharmaceutical Sciences , Tsinghua University , Beijing 100084 , China
| | - Jian Wang
- College of Chemistry and Biological Sciences , Hubei University of Science and Technology , Hubei 437100 , China.,School of Pharmaceutical Sciences , Tsinghua University , Beijing 100084 , China
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16
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Sun S, Lang M, Wang J. N‐Heterocyclic Carbene‐Catalyzed
β
‐Indolylation of
α
‐Bromoenals with Indoles. Adv Synth Catal 2019. [DOI: 10.1002/adsc.201900699] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Shaofa Sun
- College of Chemistry and Biological SciencesHubei University of Science and Technology Hubei 437100 People's Republic of China
| | - Ming Lang
- School of Pharmaceutical SciencesTsinghua University Beijing 100084 People's Republic of China
| | - Jian Wang
- School of Pharmaceutical SciencesTsinghua University Beijing 100084 People's Republic of China
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17
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Ghosh A, Barik S, Biju AT. NHC-Catalyzed [3 + 3] Annulation of Thioamides and Modified Enals for the Enantioselective Synthesis of Functionalized Thiazinones. Org Lett 2019; 21:8598-8602. [PMID: 31618035 DOI: 10.1021/acs.orglett.9b03188] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
N-Heterocyclic carbene (NHC)-catalyzed [3 + 3] annulation of thioamides with modified enals allowing the enantioselective synthesis of functionalized 1,3-thiazin-4-ones is reported. The NHC generated from the chiral triazolium salt was optimal and the reaction is initiated by the thia-Michael addition to catalytically generated α,β-unsaturated acylazolium intermediates derived from 2-bromoenals, followed by intramolecular cyclization. This operationally simple procedure offers a straightforward and rapid access to target compounds in moderate to good yields and enantiomeric ratio values.
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Affiliation(s)
- Arghya Ghosh
- Department of Organic Chemistry , Indian Institute of Science , Bangalore - 560012 , India
| | - Soumen Barik
- Department of Organic Chemistry , Indian Institute of Science , Bangalore - 560012 , India
| | - Akkattu T Biju
- Department of Organic Chemistry , Indian Institute of Science , Bangalore - 560012 , India
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18
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Abstract
N-heterocyclic carbene organocatalysis under oxidizing conditions provides a vast range of various synthetic procedures via diverse mechanisms. The available catalysts, bases, oxidants, and oxidizing methods afford numerous opportunities for developing this branch of organocatalysis. Furthermore, implementation of tandem reactions and cooperative catalysis in the described methodology significantly expands the possibilities of modern organic chemistry. This approach allows the synthesis of different structurally complex and often enantiomerically enriched substances, which can be interesting in terms of biological activity and natural product synthesis. Many esters, amides, thioesters, lactams, lactones, and other cyclic compounds obtained in oxidative or oxygenative reactions promoted by N-heterocyclic carbenes can be interesting precursors in advanced organic synthesis. Sophistication and broad applicability prove that the described synthetic approaches are exceptionally worthy of further development.
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