1
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Tyler J, Schäfer F, Shao H, Stein C, Wong A, Daniliuc CG, Houk KN, Glorius F. Bicyclo[1.1.0]butyl Radical Cations: Synthesis and Application to [2π + 2σ] Cycloaddition Reactions. J Am Chem Soc 2024; 146:16237-16247. [PMID: 38811005 PMCID: PMC11177261 DOI: 10.1021/jacs.4c04403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Revised: 05/13/2024] [Accepted: 05/14/2024] [Indexed: 05/31/2024]
Abstract
As the chemistry that surrounds the field of strained hydrocarbons, such as bicyclo[1.1.0]butane, continues to expand, it becomes increasingly advantageous to develop alternative reactivity modes that harness their unique properties to access new regions of chemical space. Herein, we report the use of photoredox catalysis to promote the single-electron oxidation of bicyclo[1.1.0]butanes. The synthetic utility of the resulting radical cations is highlighted by their ability to undergo highly regio- and diastereoselective [2π + 2σ] cycloaddition reactions. The most notable feature of this transformation is the breadth of alkene classes that can be employed, including nonactivated alkenes, which have so far been elusive for previous strategies. A rigorous mechanistic investigation, in conjunction with DFT computation, was undertaken in order to better understand the physical nature of bicyclo[1.1.0]butyl radical cations and thus provides a platform from which further studies into the synthetic applications of these intermediates can be built upon.
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Affiliation(s)
- Jasper
L. Tyler
- Organisch-Chemisches
Institut, Universität Münster, 48149 Münster, Germany
| | - Felix Schäfer
- Organisch-Chemisches
Institut, Universität Münster, 48149 Münster, Germany
| | - Huiling Shao
- Department
of Chemistry and Biochemistry, University
of California, Los Angeles, California 90095-1569, United States
| | - Colin Stein
- Organisch-Chemisches
Institut, Universität Münster, 48149 Münster, Germany
| | - Audrey Wong
- Department
of Chemistry and Biochemistry, University
of California, Los Angeles, California 90095-1569, United States
| | | | - K. N. Houk
- Department
of Chemistry and Biochemistry, University
of California, Los Angeles, California 90095-1569, United States
| | - Frank Glorius
- Organisch-Chemisches
Institut, Universität Münster, 48149 Münster, Germany
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2
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Ohashi E, Karanjit S, Nakayama A, Takeuchi K, Emam SE, Ando H, Ishida T, Namba K. Efficient construction of the hexacyclic ring core of palau'amine: the p K a concept for proceeding with unfavorable equilibrium reactions. Chem Sci 2021; 12:12201-12210. [PMID: 34667586 PMCID: PMC8457368 DOI: 10.1039/d1sc03260g] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 08/10/2021] [Indexed: 11/21/2022] Open
Abstract
Palau'amine has received a great deal of attention as an attractive synthetic target due to its intriguing molecular architecture and significant immunosuppressive activity, and we achieved its total synthesis in 2015. However, the synthesized palau'amine has not been readily applicable to the mechanistic study of immunosuppressive activity, because it requires 45 longest linear steps from a commercially available compound. Here, we report the short-step construction of the ABCDEF hexacyclic ring core of palau'amine. The construction of the CDE tricyclic ring core in a single step is achieved by our pKa concept for proceeding with unfavorable equilibrium reactions, and a palau'amine analog without the aminomethyl and chloride groups is synthesized in 20 longest linear steps from the same starting material. The palau'amine analog is confirmed to retain the immunosuppressive activity. The present synthetic approach for a palau'amine analog has the potential for use in the development of palau'amine probes for mechanistic elucidation. A palau'amine analog (2) was synthesized from 2-cyclopentenone in 20 steps. The construction of the CDE tricyclic ring core in a single step is achieved by our pKa concept for proceeding with the unfavorable equilibrium reactions.![]()
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Affiliation(s)
- Eisaku Ohashi
- Graduate School of Pharmaceutical Sciences, Tokushima University 1-78 Shomachi Tokushima 770-8505 Japan
| | - Sangita Karanjit
- Graduate School of Pharmaceutical Sciences, Tokushima University 1-78 Shomachi Tokushima 770-8505 Japan .,Research Cluster on "Innovative Chemical Sensing", Tokushima University 1-78 Shomachi Tokushima 770-8505 Japan
| | - Atsushi Nakayama
- Graduate School of Pharmaceutical Sciences, Tokushima University 1-78 Shomachi Tokushima 770-8505 Japan .,Research Cluster on "Innovative Chemical Sensing", Tokushima University 1-78 Shomachi Tokushima 770-8505 Japan
| | - Kohei Takeuchi
- Graduate School of Pharmaceutical Sciences, Tokushima University 1-78 Shomachi Tokushima 770-8505 Japan
| | - Sherif E Emam
- Graduate School of Pharmaceutical Sciences, Tokushima University 1-78 Shomachi Tokushima 770-8505 Japan
| | - Hidenori Ando
- Graduate School of Pharmaceutical Sciences, Tokushima University 1-78 Shomachi Tokushima 770-8505 Japan
| | - Tatsuhiro Ishida
- Graduate School of Pharmaceutical Sciences, Tokushima University 1-78 Shomachi Tokushima 770-8505 Japan
| | - Kosuke Namba
- Graduate School of Pharmaceutical Sciences, Tokushima University 1-78 Shomachi Tokushima 770-8505 Japan .,Research Cluster on "Innovative Chemical Sensing", Tokushima University 1-78 Shomachi Tokushima 770-8505 Japan
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3
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Mu X, Li Y, Zheng N, Long J, Chen S, Liu B, Zhao C, Yang Z. Stereoselective Synthesis of Cyclohepta[
b
]indoles by Visible‐Light‐Induced [2+2]‐Cycloaddition/retro‐Mannich‐type Reactions. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202101104] [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)
- Xin‐Peng Mu
- State Key Laboratory of Chemical Oncogenomics and Laboratory of Chemical Genomics School of Chemical Biology and Biotechnology Peking University Shenzhen Graduate School Shenzhen 518055 P. R. China
| | - Yuan‐He Li
- Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education and Beijing National Laboratory for Molecular Science (BNLMS) Peking-Tsinghua Center for Life Sciences Peking University Beijing 100871 P. R. China
| | - Nan Zheng
- State Key Laboratory of Chemical Oncogenomics and Laboratory of Chemical Genomics School of Chemical Biology and Biotechnology Peking University Shenzhen Graduate School Shenzhen 518055 P. R. China
| | - Jian‐Yu Long
- State Key Laboratory of Chemical Oncogenomics and Laboratory of Chemical Genomics School of Chemical Biology and Biotechnology Peking University Shenzhen Graduate School Shenzhen 518055 P. R. China
| | - Si‐Jia Chen
- State Key Laboratory of Chemical Oncogenomics and Laboratory of Chemical Genomics School of Chemical Biology and Biotechnology Peking University Shenzhen Graduate School Shenzhen 518055 P. R. China
| | - Bing‐Yan Liu
- State Key Laboratory of Chemical Oncogenomics and Laboratory of Chemical Genomics School of Chemical Biology and Biotechnology Peking University Shenzhen Graduate School Shenzhen 518055 P. R. China
| | - Chun‐Bo Zhao
- State Key Laboratory of Chemical Oncogenomics and Laboratory of Chemical Genomics School of Chemical Biology and Biotechnology Peking University Shenzhen Graduate School Shenzhen 518055 P. R. China
| | - Zhen Yang
- State Key Laboratory of Chemical Oncogenomics and Laboratory of Chemical Genomics School of Chemical Biology and Biotechnology Peking University Shenzhen Graduate School Shenzhen 518055 P. R. China
- Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education and Beijing National Laboratory for Molecular Science (BNLMS) Peking-Tsinghua Center for Life Sciences Peking University Beijing 100871 P. R. China
- Shenzhen Bay Laboratory Shenzhen 518055 P. R. China
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4
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Mu XP, Li YH, Zheng N, Long JY, Chen SJ, Liu BY, Zhao CB, Yang Z. Stereoselective Synthesis of Cyclohepta[b]indoles by Visible-Light-Induced [2+2]-Cycloaddition/retro-Mannich-type Reactions. Angew Chem Int Ed Engl 2021; 60:11211-11216. [PMID: 33683807 DOI: 10.1002/anie.202101104] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 02/27/2021] [Indexed: 12/12/2022]
Abstract
A novel method for the concise synthesis of cyclohepta[b]indoles in high yields was developed. The method involves a visible-light-induced, photocatalyzed [2+2]-cycloaddition/ retro-Mannich-type reaction of enaminones. Experimental and computational studies suggested that the reaction is a photoredox process initiated by single-electron oxidation of an enaminone moiety, which undergoes subsequent cyclobutane formation and rapidly fragmentation in a radical-cation state to form cyclohepta[b]indoles.
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Affiliation(s)
- Xin-Peng Mu
- State Key Laboratory of Chemical Oncogenomics and Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, 518055, P. R. China
| | - Yuan-He Li
- Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education and Beijing National Laboratory for Molecular Science (BNLMS), Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, P. R. China
| | - Nan Zheng
- State Key Laboratory of Chemical Oncogenomics and Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, 518055, P. R. China
| | - Jian-Yu Long
- State Key Laboratory of Chemical Oncogenomics and Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, 518055, P. R. China
| | - Si-Jia Chen
- State Key Laboratory of Chemical Oncogenomics and Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, 518055, P. R. China
| | - Bing-Yan Liu
- State Key Laboratory of Chemical Oncogenomics and Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, 518055, P. R. China
| | - Chun-Bo Zhao
- State Key Laboratory of Chemical Oncogenomics and Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, 518055, P. R. China
| | - Zhen Yang
- State Key Laboratory of Chemical Oncogenomics and Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, 518055, P. R. China.,Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education and Beijing National Laboratory for Molecular Science (BNLMS), Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, P. R. China.,Shenzhen Bay Laboratory, Shenzhen, 518055, P. R. China
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5
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Ma Z, Chen C. Natural products as inspiration for the development of new synthetic methods. J CHIN CHEM SOC-TAIP 2018; 65:43-59. [PMID: 29430058 PMCID: PMC5800783 DOI: 10.1002/jccs.201700134] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Natural products have played an important role in shaping modern synthetic organic chemistry. In particular, their complex molecular skeletons have stimulated the development of many new synthetic methods. We highlight in this article some recent examples of synthetic design inspired by the biosynthesis of natural products.
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Affiliation(s)
- Zhiqiang Ma
- Department of Biochemistry, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9038, USA
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, P. R. China
| | - Chuo Chen
- Department of Biochemistry, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9038, USA
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6
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Kim H, Hwang YJ, Han I, Joo JM. Regioselective C–H alkenylation of imidazoles and its application to the synthesis of unsymmetrically substituted benzimidazoles. Chem Commun (Camb) 2018; 54:6879-6882. [DOI: 10.1039/c8cc02405g] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A palladium-catalyzed C5-selective alkenylation of imidazoles has been developed and applied to the synthesis of alkenyl imidazoles and multi-substituted benzimidazoles.
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Affiliation(s)
- Hyeongwoo Kim
- Department of Chemistry and Chemistry Institute of Functional Materials
- Pusan National University
- Busan 46241
- Republic of Korea
| | - Ye Ji Hwang
- Department of Chemistry and Chemistry Institute of Functional Materials
- Pusan National University
- Busan 46241
- Republic of Korea
| | - Inhyuk Han
- Department of Chemistry and Chemistry Institute of Functional Materials
- Pusan National University
- Busan 46241
- Republic of Korea
| | - Jung Min Joo
- Department of Chemistry and Chemistry Institute of Functional Materials
- Pusan National University
- Busan 46241
- Republic of Korea
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7
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Plesniak MP, Huang HM, Procter DJ. Radical cascade reactions triggered by single electron transfer. Nat Rev Chem 2017. [DOI: 10.1038/s41570-017-0077] [Citation(s) in RCA: 169] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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8
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Abstract
Covering: July 2012 to June 2015. Previous review: Nat. Prod. Rep., 2013, 30, 869-915The structurally diverse imidazole-, oxazole-, and thiazole-containing secondary metabolites are widely distributed in terrestrial and marine environments, and exhibit extensive pharmacological activities. In this review the latest progress involving the isolation, biological activities, and chemical and biogenetic synthesis studies on these natural products has been summarized.
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Affiliation(s)
- Zhong Jin
- State Key Laboratory and Institute of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, China. and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300071, China
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9
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Stevenson SM, Higgins RF, Shores MP, Ferreira EM. Chromium photocatalysis: accessing structural complements to Diels-Alder adducts with electron-deficient dienophiles. Chem Sci 2017; 8:654-660. [PMID: 28451213 PMCID: PMC5297334 DOI: 10.1039/c6sc03303b] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 09/11/2016] [Indexed: 12/29/2022] Open
Abstract
A chromium-catalyzed, visible light-activated net [4 + 2] cycloaddition between dienes and electron-deficient alkenes is described. Gathered evidence, via control experiments, isolated intermediates, and measured redox potentials, points to several converging reaction pathways that afford the cyclohexene adducts, including a photochemical [2 + 2] cycloaddition/vinylcyclobutane rearrangement cascade and a substrate excitation/oxidation sequence to a radical cation intermediate. Notably, the accompanying mechanistic stipulations result in a process that yields regioisomeric compounds from those generated by traditional Diels-Alder cycloadditions.
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Affiliation(s)
- Susan M Stevenson
- Department of Chemistry , University of Georgia , Athens , GA 30602 , USA .
| | - Robert F Higgins
- Department of Chemistry , Colorado State University , Fort Collins , CO 80523 , USA
| | - Matthew P Shores
- Department of Chemistry , Colorado State University , Fort Collins , CO 80523 , USA
| | - Eric M Ferreira
- Department of Chemistry , University of Georgia , Athens , GA 30602 , USA .
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10
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Affiliation(s)
- Kosuke Namba
- Graduate School of Biomedical Sciences, Tokushima University
| | | | | | - Keiji Tanino
- Department of Chemistry, Faculty of Science, Hokkaido University
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11
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Poplata S, Tröster A, Zou YQ, Bach T. Recent Advances in the Synthesis of Cyclobutanes by Olefin [2 + 2] Photocycloaddition Reactions. Chem Rev 2016; 116:9748-815. [PMID: 27018601 PMCID: PMC5025837 DOI: 10.1021/acs.chemrev.5b00723] [Citation(s) in RCA: 648] [Impact Index Per Article: 81.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Indexed: 11/30/2022]
Abstract
The [2 + 2] photocycloaddition is undisputedly the most important and most frequently used photochemical reaction. In this review, it is attempted to cover all recent aspects of [2 + 2] photocycloaddition chemistry with an emphasis on synthetically relevant, regio-, and stereoselective reactions. The review aims to comprehensively discuss relevant work, which was done in the field in the last 20 years (i.e., from 1995 to 2015). Organization of the data follows a subdivision according to mechanism and substrate classes. Cu(I) and PET (photoinduced electron transfer) catalysis are treated separately in sections 2 and 4 , whereas the vast majority of photocycloaddition reactions which occur by direct excitation or sensitization are divided within section 3 into individual subsections according to the photochemically excited olefin.
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Affiliation(s)
- Saner Poplata
- Department Chemie and Catalysis
Research Center (CRC), Technische Universität
München, D-85747 Garching, Germany
| | - Andreas Tröster
- Department Chemie and Catalysis
Research Center (CRC), Technische Universität
München, D-85747 Garching, Germany
| | - You-Quan Zou
- Department Chemie and Catalysis
Research Center (CRC), Technische Universität
München, D-85747 Garching, Germany
| | - Thorsten Bach
- Department Chemie and Catalysis
Research Center (CRC), Technische Universität
München, D-85747 Garching, Germany
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12
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13
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Beniddir MA, Evanno L, Joseph D, Skiredj A, Poupon E. Emergence of diversity and stereochemical outcomes in the biosynthetic pathways of cyclobutane-centered marine alkaloid dimers. Nat Prod Rep 2016; 33:820-42. [DOI: 10.1039/c5np00159e] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
A deep-sea dive into the ecology and chemistry of surprising cyclobutanes from marine invertebrates.
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Affiliation(s)
| | - Laurent Evanno
- BioCIS
- Univ. Paris-Sud
- CNRS
- Université Paris-Saclay
- Châtenay-Malabry
| | - Delphine Joseph
- BioCIS
- Univ. Paris-Sud
- CNRS
- Université Paris-Saclay
- Châtenay-Malabry
| | - Adam Skiredj
- BioCIS
- Univ. Paris-Sud
- CNRS
- Université Paris-Saclay
- Châtenay-Malabry
| | - Erwan Poupon
- BioCIS
- Univ. Paris-Sud
- CNRS
- Université Paris-Saclay
- Châtenay-Malabry
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14
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Namba K, Takeuchi K, Kaihara Y, Oda M, Nakayama A, Nakayama A, Yoshida M, Tanino K. Total synthesis of palau'amine. Nat Commun 2015; 6:8731. [PMID: 26530707 PMCID: PMC4667646 DOI: 10.1038/ncomms9731] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 09/25/2015] [Indexed: 11/09/2022] Open
Abstract
Palau'amine has received a great deal of attention in the past two decades as an attractive synthetic target by virtue of its intriguing molecular architecture and significant immunosuppressive activity. Here we report the total synthesis of palau'amine characterized by the construction of an ABDE tetracyclic ring core including a trans-bicylo[3.3.0]octane skeleton at a middle stage of total synthesis. The ABDE tetracyclic ring core is constructed by a cascade reaction of a cleavage of the N-N bond, including simultaneous formation of imine, the addition of amide anion to the resulting imine (D-ring formation) and the condensation of pyrrole with methyl ester (B-ring formation) in a single step. The synthetic palau'amine is confirmed to exhibit excellent immunosuppressive activity. The present synthetic route has the potential to help elucidate a pharmacophore as well as the mechanistic details of immunosuppressive activity.
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Affiliation(s)
- Kosuke Namba
- Department of Pharmaceutical Science, Tokushima University, 1-78 Shomachi, Tokushima 770-8505, Japan
| | - Kohei Takeuchi
- Department of Pharmaceutical Science, Tokushima University, 1-78 Shomachi, Tokushima 770-8505, Japan.,Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan
| | - Yukari Kaihara
- Department of Chemistry, Faculty of Science, Hokkaido University, Kita-ku, Sapporo 060-0810, Japan
| | - Masataka Oda
- Graduate School of Medical and Dental Sciences, Niigata University, Chuo-ku, Niigata 951-8514, Japan
| | - Akira Nakayama
- Catalysis Research Center, Hokkaido University, Sapporo 001-0021, Japan
| | - Atsushi Nakayama
- Department of Pharmaceutical Science, Tokushima University, 1-78 Shomachi, Tokushima 770-8505, Japan
| | - Masahiro Yoshida
- Department of Pharmaceutical Science, Tokushima University, 1-78 Shomachi, Tokushima 770-8505, Japan
| | - Keiji Tanino
- Department of Chemistry, Faculty of Science, Hokkaido University, Kita-ku, Sapporo 060-0810, Japan
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15
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Angnes RA, Li Z, Correia CRD, Hammond GB. Recent synthetic additions to the visible light photoredox catalysis toolbox. Org Biomol Chem 2015; 13:9152-67. [PMID: 26242759 DOI: 10.1039/c5ob01349f] [Citation(s) in RCA: 171] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The boom in visible light photoredox catalysis (VLPC) research has demonstrated that this novel synthetic approach is here to stay. VLPC enables reactive radical intermediates to be catalytically generated at ambient temperature, a feat not generally allowed through traditional pyrolysis- or radical initiator-based methodologies. VLPC has vastly extended the range of substrates and reaction schemes that have been traditionally the domain of radical reactions. In this review the photophysics background of VLPC will be briefly discussed, followed by a report on recent inroads of VLPC into decarboxylative couplings and radical C-H functionalization of aromatic compounds. The bulk of the review will be dedicated to advances in synergistic catalysis involving VLPC, namely the combination of photoredox catalysis with organocatalysis, including β-functionalization of carbonyl groups, functionalization of weak aliphatic C-H bonds, and anti-Markovnikov hydrofunctionalization of alkenes; dual catalysis with gold or with nickel, photoredox catalysis as an oxidation promoter in transition metal catalysis, and acid-catalyzed enantioselective radical addition to π systems.
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Affiliation(s)
- Ricardo A Angnes
- Chemistry Institute, State University of Campinas - Unicamp C.P. 6154, CEP. 13083-970, Campinas, São Paulo, Brazil
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16
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Wang X, Gao Y, Ma Z, Rodriguez RA, Yu ZX, Chen C. Syntheses of Sceptrins and Nakamuric Acid and Insights into the Biosyntheses of Pyrrole-Imidazole Dimers. Org Chem Front 2015; 2:978-984. [PMID: 26328059 PMCID: PMC4551504 DOI: 10.1039/c5qo00165j] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Sceptrins and nakamuric acid are structurally unique antibiotics isolated from marine sponges. Recent studies suggest that the biosynthesis of these dimeric pyrrole-imidazole alkaloids involves a single-electron transfer (SET)-promoted [2+2] cycloaddition to form their cyclobutane core skeletons. We describe herein the biomimetic syntheses of racemic sceptrin and nakamuric acid. We also report the asymmetric syntheses of sceptrin, bromosceptrin, and dibromosceptrin in their natural enantiomeric form. We further provide mechanistic insights into the pathway selectivity of the SET-promoted [2+2] and [4+2] cycloadditions that lead to the divergent formation of the sceptrin and ageliferin core skeletons. Both the [2+2] and [4+2] cycloadditions are stepwise reactions, with the [2+2] pathway kinetically and thermodynamically favored over the [4+2] pathway. For the [2+2] cycloaddition, the dimerization of pyrrole-imidazole monomers is rate-limiting, whereas for the [4+2] cycloaddition, the cyclization is the slowest step.
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Affiliation(s)
- Xiaolei Wang
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Yang Gao
- College of Chemistry, Peking University, Beijing 100871, China ; Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Hubei, Wuhan 430079, China
| | - Zhiqiang Ma
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Rodrigo A Rodriguez
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Zhi-Xiang Yu
- College of Chemistry, Peking University, Beijing 100871, China
| | - Chuo Chen
- Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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