1
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Zhang Z, Dai L. Construction of axially chiral molecules enabled by photoinduced enantioselective reactions. Chem Sci 2024; 15:12636-12643. [PMID: 39148771 PMCID: PMC11323314 DOI: 10.1039/d4sc03766a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2024] [Accepted: 07/22/2024] [Indexed: 08/17/2024] Open
Abstract
Axially chiral molecular scaffolds are widely found in pharmaceutical molecules, functionalized materials, and chiral ligands. The synthesis of these compounds has garnered considerable interest from both academia and industry. The construction of such molecules, enabled by transition metal catalysis and organocatalysis under thermodynamic conditions, has been extensively studied and well-reviewed. In recent years, photoinduced enantioselective reactions have emerged as powerful methods for the catalytic construction of axial chirality. In this review, we provide an overview of various synthetic strategies for the photoinduced construction of axial chirality, with a specific focus on reaction design and catalytic mechanisms. Additionally, we discuss the limitations of current methods and highlight future directions in this field.
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Affiliation(s)
- Zhaofei Zhang
- Department of Chemistry, Purdue University West Lafayette Indiana 47907 USA
| | - Lei Dai
- Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, Chemical Biology Research Center, School of Pharmaceutical Sciences, Chongqing University Chongqing 401331 China
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2
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Wang J, Fu Q, Cao S, Lv X, Yin Y, Ban X, Zhao X, Jiang Z. Enantioselective [2 + 2] Photocycloreversion Enables De Novo Deracemization Synthesis of Cyclobutanes. J Am Chem Soc 2024; 146:22840-22849. [PMID: 39094097 DOI: 10.1021/jacs.4c08290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
While photochemical deracemization significantly enhances atom economy by eliminating the necessity for additional oxidants or reductants, the laborious presynthesis of substrates from feedstock chemicals is often required, thereby compromising the practicality of this method. In this study, we propose a novel approach known as de novo deracemization synthesis, which involves direct utilization of simple substrates undergoing both photochemical transformation and reversible photochemical transformation. The efficient enantiocontrol of chiral catalysts in the latter process establishes an effective platform for deracemization. This alternative and practical approach to address the challenges of asymmetric photocatalysis has been successfully demonstrated in the photosensitized de novo deracemization synthesis of azaarene-functionalized cyclobutanes featuring three stereocenters, including an all-carbon quaternary center. By exclusively employing a suitable chiral catalyst to enable kinetically controlled [2 + 2] photocycloreversion, we pave a creative path toward achieving more cost-effective photochemical deracemization.
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Affiliation(s)
- Jiahao Wang
- Pingyuan Laboratory, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, PR China
| | - Qianqian Fu
- Pingyuan Laboratory, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, PR China
| | - Shanshan Cao
- Pingyuan Laboratory, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, PR China
| | - Xinxin Lv
- Pingyuan Laboratory, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, PR China
| | - Yanli Yin
- Pingyuan Laboratory, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, PR China
| | - Xu Ban
- Pingyuan Laboratory, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, PR China
| | - Xiaowei Zhao
- Henan Key Laboratory of Natural Medicine Innovation and Transformation, Henan University, Kaifeng, Henan 475004, PR China
| | - Zhiyong Jiang
- Pingyuan Laboratory, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, PR China
- Henan Key Laboratory of Natural Medicine Innovation and Transformation, Henan University, Kaifeng, Henan 475004, PR China
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3
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Song C, Bai X, Li B, Dang Y, Yu S. Photoexcited Palladium-Catalyzed Deracemization of Allenes. J Am Chem Soc 2024. [PMID: 39024194 DOI: 10.1021/jacs.4c07126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
The different enantiomers of specific chiral molecules frequently exhibit disparate biological, physiological, or pharmacological properties. Therefore, the efficient synthesis of single enantiomers is of particular importance not only to the pharmaceutical sector but also to other industrial sectors, such as agrochemical and fine chemical industries. Deracemization, a process during which a racemic mixture is converted into a nonracemic product with 100% atom economy and theoretical yield, is the most straightforward method to access enantioenriched molecules but a challenging task due to a decrease in entropy and microscopic reversibility. Axially chiral allenes bear a distinctive structure of two orthogonal cumulative π-systems and are acknowledged as synthetically versatile synthons in organic synthesis. The selective creation of axially chiral allenes with high optical purity under mild reaction conditions has always been a very popular and hot topic in organic synthesis but remains challenging. Herein, a photoexcited palladium-catalyzed deracemization of nonprefunctionalized disubstituted allenes is disclosed. This method provides an efficient and economical strategy to accommodate a broad scope of allenes with good enantioselectivities and yields (53 examples, up to 96% yield and 95% ee). The use of a suitable chiral palladium complex with visible light irradiation is an essential factor in achieving this transformation. A metal-to-ligand charge transfer mechanism was proposed based on control experiments and density functional theory calculations. Quantum mechanical studies implicate dual modes of asymmetric induction behind our new protocol: (1) sterically controlled stereoselective binding of one allene enantiomer under the ground-state and (2) facile, noncovalent interaction-driven excited-state isomerization toward the opposite enantiomer. The success of this newly established photochemical deracemization strategy should provide inspiration for expansion to other multisubstituted allenes and will open up a new mode for enantioselective excited-state palladium catalysis.
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Affiliation(s)
- Changhua Song
- State Key Laboratory of Analytical Chemistry for Life Science, Jiangsu Key Laboratory of Advanced Organic Materials, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Xiangbin Bai
- State Key Laboratory of Analytical Chemistry for Life Science, Jiangsu Key Laboratory of Advanced Organic Materials, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Bo Li
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, China
| | - Yanfeng Dang
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, China
| | - Shouyun Yu
- State Key Laboratory of Analytical Chemistry for Life Science, Jiangsu Key Laboratory of Advanced Organic Materials, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
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4
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Ying M, Wang K, Yan W, Pu M, Lin L. Stable Axially Chiral Cyclohexylidenes from Catalytic Asymmetric Knoevenagel Condensation. Chemistry 2024; 30:e202401243. [PMID: 38711202 DOI: 10.1002/chem.202401243] [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: 03/28/2024] [Revised: 05/03/2024] [Accepted: 05/06/2024] [Indexed: 05/08/2024]
Abstract
Axially chiral cycloalkylidenes are interesting but less developed axially chiral molecules. Here, a bispidine-based chiral amine catalytic system was developed to promote efficiently the asymmetric Knoevenagel condensation of N-protected oxindoles and benzofuranones with 4-substituted cyclohexanones. A variety of alkylidenecycloalkanes with stable axial chirality were obtained in good yields and fairly good er (enantiomeric ratio). Based on the absolute configuration determination of product and DFT calculations, a possible mechanism of stereoselective induction was proposed.
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Affiliation(s)
- Meijia Ying
- Key Laboratory of Green Chemistry & Technology Ministry of Education, College of Chemistry, Sichuan University, P. R. China
| | - Kaixuan Wang
- Key Laboratory of Green Chemistry & Technology Ministry of Education, College of Chemistry, Sichuan University, P. R. China
| | - Wenjun Yan
- Key Laboratory of Green Chemistry & Technology Ministry of Education, College of Chemistry, Sichuan University, P. R. China
| | - Maoping Pu
- Key Laboratory of Green Chemistry & Technology Ministry of Education, College of Chemistry, Sichuan University, P. R. China
| | - Lili Lin
- Key Laboratory of Green Chemistry & Technology Ministry of Education, College of Chemistry, Sichuan University, P. R. China
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5
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Guo W, Hori M, Ogura Y, Nishimura K, Oki K, Ikai T, Yashima E, Ishihara K. Tandem Isomerization/α,β-Site-Selective and Enantioselective Addition Reactions of N-(3-Butynoyl)-3,5-dimethylpyrazole Induced by Chiral π-Cu(II) Catalysts. J Am Chem Soc 2023; 145:27080-27088. [PMID: 38032102 PMCID: PMC10722507 DOI: 10.1021/jacs.3c10820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 11/07/2023] [Accepted: 11/08/2023] [Indexed: 12/01/2023]
Abstract
Allenes are important building blocks, and derivatization of products via cycloadditions of allenes could become a powerful strategy for constructing carbocyclic and heterocyclic rings. However, the development of catalytic site-selective and enantioselective cycloaddition reactions of allenes still presents significant challenges. Here, we report chiral π-Cu(II)-complex-catalyzed isomerization of N-(3-butynoyl)-3,5-dimethyl-1H-pyrazole to generate N-allenoylpyrazole in situ and subsequent α,β-site-selective and enantioselective [3 + 2], [4 + 2], or [2 + 2] cycloaddition or conjugate addition reactions. The asymmetric environment created by the intramolecular π-Cu(II) interactions provides the corresponding adducts in moderate to high yield with excellent enantioselectivity. To the best of our knowledge, this is the first successful method for chiral-Lewis-acid-catalyzed tandem isomerization/α,β-site-selective and enantioselective cycloaddition or conjugate addition reactions of latent non-γ-substituted allenoyl derivative.
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Affiliation(s)
- Weiwei Guo
- Graduate
School of Engineering, Nagoya University, B2-3(611) Furo-cho, Chikusa, Nagoya 464-8603, Japan
| | - Masahiro Hori
- Graduate
School of Engineering, Nagoya University, B2-3(611) Furo-cho, Chikusa, Nagoya 464-8603, Japan
| | - Yoshihiro Ogura
- Graduate
School of Engineering, Nagoya University, B2-3(611) Furo-cho, Chikusa, Nagoya 464-8603, Japan
| | - Kazuki Nishimura
- Graduate
School of Engineering, Nagoya University, B2-3(611) Furo-cho, Chikusa, Nagoya 464-8603, Japan
| | - Kosuke Oki
- Graduate
School of Engineering, Nagoya University, B2-3(611) Furo-cho, Chikusa, Nagoya 464-8603, Japan
| | - Tomoyuki Ikai
- Graduate
School of Engineering, Nagoya University, B2-3(611) Furo-cho, Chikusa, Nagoya 464-8603, Japan
| | - Eiji Yashima
- Graduate
School of Engineering, Nagoya University, B2-3(611) Furo-cho, Chikusa, Nagoya 464-8603, Japan
| | - Kazuaki Ishihara
- Graduate
School of Engineering, Nagoya University, B2-3(611) Furo-cho, Chikusa, Nagoya 464-8603, Japan
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6
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Großkopf J, Bach T. Catalytic Photochemical Deracemization via Short-Lived Intermediates. Angew Chem Int Ed Engl 2023; 62:e202308241. [PMID: 37428113 DOI: 10.1002/anie.202308241] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 07/04/2023] [Accepted: 07/05/2023] [Indexed: 07/11/2023]
Abstract
Upon irradiation in the presence of a suitable chiral catalyst, racemic compound mixtures can be converted into enantiomerically pure compounds with the same constitution. The process is called photochemical deracemization and involves the formation of short-lived intermediates. By opening different reaction channels for the forward reaction to the intermediate and for the re-constitution of the chiral molecule, the entropically disfavored process becomes feasible. Since the discovery of the first photochemical deracemization in 2018, the field has been growing rapidly. This review comprehensively covers the research performed in the area and discusses current developments. It is subdivided according to the mode of action and the respective substrate classes. The focus of this review is on the scope of the individual reactions and on a discussion of the mechanistic details underlying the presented reaction.
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Affiliation(s)
- Johannes Großkopf
- School of Natural Sciences, Technische Universität München, Department Chemie and Catalysis Research Center (CRC), Lichtenbergstr. 4, 85747, Garching, Germany
| | - Thorsten Bach
- School of Natural Sciences, Technische Universität München, Department Chemie and Catalysis Research Center (CRC), Lichtenbergstr. 4, 85747, Garching, Germany
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7
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Huo SC, Indurmuddam RR, Hong BC, Lu CF, Chien SY. The hamburger-shape photocatalyst: thioxanthone-based chiral [2.2]paracyclophane for enantioselective visible-light photocatalysis of 3-methylquinoxalin-2(1 H)-one and styrenes. Org Biomol Chem 2023; 21:9330-9336. [PMID: 37987508 DOI: 10.1039/d3ob01580g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
A new thioxanthone-based photocatalyst with a [2.2]paracyclophane skeleton and planar chirality has been developed. The catalyst has been successfully applied in the visible light-mediated enantioselective aza Paternò-Büchi reactions of quinoxalinone and styrenes to produce azetidines. The structures of the catalyst derivatives were unequivocally determined by their single crystal X-ray crystallography analysis.
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Affiliation(s)
- Shou-Chih Huo
- Department of Chemistry and Biochemistry, National Chung Cheng University, Chiayi 621, Taiwan.
| | | | - Bor-Cherng Hong
- Department of Chemistry and Biochemistry, National Chung Cheng University, Chiayi 621, Taiwan.
| | - Chuan-Fu Lu
- Department of Chemistry and Biochemistry, National Chung Cheng University, Chiayi 621, Taiwan.
| | - Su-Ying Chien
- Instrumentation Center, National Taiwan University, Taipei 106, Taiwan
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8
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Onneken C, Morack T, Soika J, Sokolova O, Niemeyer N, Mück-Lichtenfeld C, Daniliuc CG, Neugebauer J, Gilmour R. Light-enabled deracemization of cyclopropanes by Al-salen photocatalysis. Nature 2023; 621:753-759. [PMID: 37612509 PMCID: PMC10533403 DOI: 10.1038/s41586-023-06407-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 07/05/2023] [Indexed: 08/25/2023]
Abstract
Privileged chiral catalysts-those that share common structural features and are enantioselective across a range of reactions-continue to transform the chemical-research landscape1. In recent years, new reactivity modes have been achieved through excited-state catalysis, processes activated by light, but it is unclear if the selectivity of ground-state privileged catalysts can be matched. Although the interception of photogenerated intermediates by ground-state cycles has partially addressed this challenge2, single, chiral photocatalysts that simultaneously regulate reactivity and selectivity are conspicuously scarce3. So far, precision donor-acceptor recognition motifs remain crucial in enantioselective photocatalyst design4. Here we show that chiral Al-salen complexes, which have well-defined photophysical properties, can be used for the efficient photochemical deracemization5 of cyclopropyl ketones (up to 98:2 enantiomeric ratio (e.r.)). Irradiation at λ = 400 nm (violet light) augments the reactivity of the commercial catalyst to enable reactivity and enantioselectivity to be regulated simultaneously. This circumvents the need for tailored catalyst-substrate recognition motifs. It is predicted that this study will stimulate a re-evaluation of many venerable (ground-state) chiral catalysts in excited-state processes, ultimately leading to the identification of candidates that may be considered 'privileged' in both reactivity models.
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Affiliation(s)
- Carina Onneken
- Institute of Organic Chemistry, Westfälische Wilhelms-Universität (WWU) Münster, Münster, Germany
| | - Tobias Morack
- Institute of Organic Chemistry, Westfälische Wilhelms-Universität (WWU) Münster, Münster, Germany
- Department of Chemistry, Yale University, New Haven, CT, USA
| | - Julia Soika
- Institute of Organic Chemistry, Westfälische Wilhelms-Universität (WWU) Münster, Münster, Germany
| | - Olga Sokolova
- Institute of Organic Chemistry, Westfälische Wilhelms-Universität (WWU) Münster, Münster, Germany
| | - Niklas Niemeyer
- Institute of Organic Chemistry, Westfälische Wilhelms-Universität (WWU) Münster, Münster, Germany
- Center for Multiscale Theory and Computation, Westfälische Wilhelms-Universität (WWU) Münster, Münster, Germany
| | - Christian Mück-Lichtenfeld
- Institute of Organic Chemistry, Westfälische Wilhelms-Universität (WWU) Münster, Münster, Germany
- Center for Multiscale Theory and Computation, Westfälische Wilhelms-Universität (WWU) Münster, Münster, Germany
| | - Constantin G Daniliuc
- Institute of Organic Chemistry, Westfälische Wilhelms-Universität (WWU) Münster, Münster, Germany
| | - Johannes Neugebauer
- Institute of Organic Chemistry, Westfälische Wilhelms-Universität (WWU) Münster, Münster, Germany.
- Center for Multiscale Theory and Computation, Westfälische Wilhelms-Universität (WWU) Münster, Münster, Germany.
| | - Ryan Gilmour
- Institute of Organic Chemistry, Westfälische Wilhelms-Universität (WWU) Münster, Münster, Germany.
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9
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Harvey FM, Heidecker AH, Merten C, Bach T. Diastereoselective, Lewis acid-mediated Diels-Alder reactions of allenoic acid derivatives and 1,3-cyclopentadienes. Org Biomol Chem 2023; 21:4422-4428. [PMID: 37184215 DOI: 10.1039/d3ob00598d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Allenes with different substituents at their terminal carbon atom display axial chirality and can be obtained in enantiopure form by a photochemical deracemization protocol. It has now been studied under which conditions allenoic acid derivatives undergo a Diels-Alder reaction with 1,3-cyclopentadienes and which products result. Cyclic derivatives (lactams, lactones) underwent an exo-selective reaction catalyzed by the Lewis acid Eu(fod)3, while acyclic derivatives yielded with high preference the endo-products (EtAlCl2 as the preferred Lewis acid). The exocyclic double bond forms with exquisite diastereoselectivity and the chirality transfer is close to perfect. The method was applied to the synthesis of the sesquiterpenes β-santalol (1) and 10(E)-β-santalic acid (13).
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Affiliation(s)
- Freya M Harvey
- Technische Universität München, School of Natural Sciences, Department of Chemistry and Catalysis Research Center, Lichtenbergstrasse 4, 85747 Garching, Germany.
| | - Alexandra H Heidecker
- Technische Universität München, School of Natural Sciences, Department of Chemistry and Catalysis Research Center, Lichtenbergstrasse 4, 85747 Garching, Germany.
| | - Christian Merten
- Organische Chemie II, Fakultät für Chemie und Biochemie, Ruhr-Universität Bochum, Universitätsstraße 150, 44801 Bochum, Germany
| | - Thorsten Bach
- Technische Universität München, School of Natural Sciences, Department of Chemistry and Catalysis Research Center, Lichtenbergstrasse 4, 85747 Garching, Germany.
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10
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Abstract
Deracemization, which converts a racemate into its single enantiomer without separation of the intermediate, has gained renewed interest in asymmetric synthesis with its inherent atomic economy and high efficiency. However, this ideal process requires selective energy input and delicate reaction design to surmount the thermodynamical and kinetical constraints. With the rapid development of asymmetric catalysis, many catalytic strategies in concert with exogenous energy input have been exploited to facilitate this nonspontaneous enantioenrichment. In this perspective, we will discuss the basic ideas to accomplish catalytic deracemization, categorized by the three major exogenous energy sources including chemical (redox)-, photo- and mechanical energy from attrition. Emphasis will be given to the catalytic features and the underlying deracemization mechanism together with perspectives on future development.
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Affiliation(s)
- Mouxin Huang
- Center of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100084, China
- Department of Medicinal Chemistry, Third Military of Medical University, Chongqing 400038, China
| | - Tianrun Pan
- Center of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Xieyang Jiang
- Center of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Sanzhong Luo
- Center of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100084, China
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11
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Jiang H, He XK, Jiang X, Zhao W, Lu LQ, Cheng Y, Xiao WJ. Photoinduced Cobalt-Catalyzed Desymmetrization of Dialdehydes to Access Axial Chirality. J Am Chem Soc 2023; 145:6944-6952. [PMID: 36920031 DOI: 10.1021/jacs.3c00462] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
Enantioselective metallaphotoredox catalysis, which combines photoredox catalysis and asymmetric transition-metal catalysis, has become an effective approach to achieve stereoconvergence under mild conditions. Although many impressive synthetic approaches have been developed to access central chirality, the construction of axial chirality by metallaphotoredox catalysis still remains underexplored. Herein, we report two visible light-induced cobalt-catalyzed asymmetric reductive couplings of biaryl dialdehydes to synthesize axially chiral aldehydes (60 examples, up to 98% yield, >19:1 dr, and >99% ee). This protocol shows good functional group tolerance, broad substrate scope, and excellent diastereo- and enantioselectivity.
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Affiliation(s)
- Hao Jiang
- CCNU-uOttawa Joint Research Centre, Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, 152 Luoyu Road, Wuhan 430079, P. R. China
| | - Xiang-Kui He
- CCNU-uOttawa Joint Research Centre, Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, 152 Luoyu Road, Wuhan 430079, P. R. China
| | - Xuan Jiang
- CCNU-uOttawa Joint Research Centre, Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, 152 Luoyu Road, Wuhan 430079, P. R. China
| | - Wei Zhao
- CCNU-uOttawa Joint Research Centre, Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, 152 Luoyu Road, Wuhan 430079, P. R. China
| | - Liang-Qiu Lu
- CCNU-uOttawa Joint Research Centre, Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, 152 Luoyu Road, Wuhan 430079, P. R. China.,Wuhan Institute of Photochemistry and Technology, 7 Bingang North Road, Wuhan 430083, P. R. China
| | - Ying Cheng
- CCNU-uOttawa Joint Research Centre, Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, 152 Luoyu Road, Wuhan 430079, P. R. China.,Wuhan Institute of Photochemistry and Technology, 7 Bingang North Road, Wuhan 430083, P. R. China
| | - Wen-Jing Xiao
- CCNU-uOttawa Joint Research Centre, Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, 152 Luoyu Road, Wuhan 430079, P. R. China.,Wuhan Institute of Photochemistry and Technology, 7 Bingang North Road, Wuhan 430083, P. R. China
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12
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Kutta RJ, Großkopf J, van Staalduinen N, Seitz A, Pracht P, Breitenlechner S, Bannwarth C, Nuernberger P, Bach T. Multifaceted View on the Mechanism of a Photochemical Deracemization Reaction. J Am Chem Soc 2023; 145:2354-2363. [PMID: 36660908 DOI: 10.1021/jacs.2c11265] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Upon irradiation in the presence of a chiral benzophenone catalyst (5 mol %), a racemic mixture of a given chiral imidazolidine-2,4-dione (hydantoin) can be converted almost quantitatively into the same compound with high enantiomeric excess (80-99% ee). The mechanism of this photochemical deracemization reaction was elucidated by a suite of mechanistic experiments. It was corroborated by nuclear magnetic resonance titration that the catalyst binds the two enantiomers by two-point hydrogen bonding. In one of the diastereomeric complexes, the hydrogen atom at the stereogenic carbon atom is ideally positioned for hydrogen atom transfer (HAT) to the photoexcited benzophenone. Detection of the protonated ketyl radical by transient absorption revealed hydrogen abstraction to occur from only one but not from the other hydantoin enantiomer. Quantum chemical calculations allowed us to visualize the HAT within this complex and, more importantly, showed that the back HAT does not occur to the carbon atom of the hydantoin radical but to its oxygen atom. The achiral enol formed in this process could be directly monitored by its characteristic transient absorption signal at λ ≅ 330 nm. Subsequent tautomerization leads to both hydantoin enantiomers, but only one of them returns to the catalytic cycle, thus leading to an enrichment of the other enantiomer. The data are fully consistent with deuterium labeling experiments and deliver a detailed picture of a synthetically useful photochemical deracemization reaction.
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Affiliation(s)
- Roger Jan Kutta
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, Universitätsstr. 31, RegensburgD-93053, Germany
| | - Johannes Großkopf
- Department Chemie and Catalysis Research Center (CRC), School of Natural Sciences, Technische Universität München, D-85747Garching, Germany
| | - Nils van Staalduinen
- Institut für Physikalische Chemie, RWTH Aachen University, D-52074Aachen, Germany
| | - Antonia Seitz
- Department Chemie and Catalysis Research Center (CRC), School of Natural Sciences, Technische Universität München, D-85747Garching, Germany
| | - Philipp Pracht
- Institut für Physikalische Chemie, RWTH Aachen University, D-52074Aachen, Germany.,Yusuf Hamied Department of Chemistry, University of Cambridge, CambridgeCB2 1EW, United Kingdom
| | - Stefan Breitenlechner
- Department Chemie and Catalysis Research Center (CRC), School of Natural Sciences, Technische Universität München, D-85747Garching, Germany
| | - Christoph Bannwarth
- Institut für Physikalische Chemie, RWTH Aachen University, D-52074Aachen, Germany
| | - Patrick Nuernberger
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, Universitätsstr. 31, RegensburgD-93053, Germany
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC), School of Natural Sciences, Technische Universität München, D-85747Garching, Germany
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13
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Zou S, Yu B, Huang H. Palladium-Catalyzed Ring-Closing Aminoalkylative Amination of Unactivated Aminoenynes. Angew Chem Int Ed Engl 2023; 62:e202215325. [PMID: 36409522 DOI: 10.1002/anie.202215325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 11/18/2022] [Accepted: 11/21/2022] [Indexed: 11/23/2022]
Abstract
An efficient strategy for preventing the β-hydride elimination of alkylpalladium species by ligation of the palladium with adjacent amino-group was developed, which enabled a novel palladium-catalyzed ring-closing aminoalkylative amination of unactivated aminoenynes. The reaction is amenable to aminals, as well as aliphatic aldehydes with secondary amines, which provides straightforward access to structurally diverse exocyclic allenic amines bearing 5 to 12-membered N-heterocycles. With chiral phosphoramidite-ligated palladium complex as the catalyst, an enantioselective variant was achieved with up to 93 % ee. Simultaneously, synthetic transformations of the chiral products were also conducted to afford structurally unique spirodiamines including one pharmaceutically active molecule via axial-to-central chirality transfer.
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Affiliation(s)
- Suchen Zou
- Hefei National Research Center for Physical Sciences at Microscale and Department of Chemistry, Center for Excellence in Molecular Synthesis of CAS, University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Bangkui Yu
- Hefei National Research Center for Physical Sciences at Microscale and Department of Chemistry, Center for Excellence in Molecular Synthesis of CAS, University of Science and Technology of China, Hefei, 230026, P. R. China
| | - Hanmin Huang
- Hefei National Research Center for Physical Sciences at Microscale and Department of Chemistry, Center for Excellence in Molecular Synthesis of CAS, University of Science and Technology of China, Hefei, 230026, P. R. China.,Key Laboratory of Green and Precise Synthetic Chemistry and Applications, Ministry of Education, Huaibei Normal University, Huaibei, Anhui, 235000, P. R. China
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14
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Abstract
Creating, conserving and modifying the stereochemistry of organic compounds has been the subject of significant research efforts in synthetic chemistry. Most synthetic routes are designed according to the stereoselectivity-determining step. Stereochemical editing is an alternative strategy, wherein the chiral-defining or geometry-defining steps are independent of the construction of the major scaffold or complexity. It enables late-stage alterations of stereochemistry and can generate isomers from a single compound. However, in many instances, stereochemical editing processes are contra-thermodynamic, meaning the transformation is unfavourable. To overcome this barrier, photocatalysis uses photogenerated radical species and introduces thermochemical biases. A range of synthetically valuable contra-thermodynamic stereochemical editing processes have been invented, including deracemization of chiral molecules, positional alkene isomerization and dynamic epimerization of sugars and diols. In this Review, we highlight the fundamental mechanisms of visible-light photocatalysis and the general reactivity modes of the photogenerated radical intermediates towards contra-thermodynamic stereochemical editing processes.
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15
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Liang D, Xiao W, Lakhdar S, Chen J. Construction of axially chiral compounds via catalytic asymmetric radical reaction. GREEN SYNTHESIS AND CATALYSIS 2022. [DOI: 10.1016/j.gresc.2022.06.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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16
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Zhang H, Huang C, Yuan XA, Yu S. Photoexcited Chiral Copper Complex-Mediated Alkene E → Z Isomerization Enables Kinetic Resolution. J Am Chem Soc 2022; 144:10958-10967. [PMID: 35675512 DOI: 10.1021/jacs.2c04040] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
While asymmetric synthesis has been established as a powerful synthetic tool for the construction of versatile enantioenriched molecules in the most efficient and practical manner, the resolution of racemates is still the most universal industrial approach to the synthesis of chiral compounds. However, the direct formation of enantiopure Z-isomers through the catalytic nonenzymatic kinetic resolution of racemic E-alkenes remains challenging. Herein, we disclose an unprecedented enantioselective E → Z isomerization mediated by a photoexcited chiral copper complex. This catalytic system enables kinetic resolution of 2-styrylpyrrolidines. This process is difficult to realize under thermal conditions. Mechanistic experiments and density functional theory (DFT) calculations revealed that different overall sensitization rates of the substrate-catalyst complex of the two enantiomers led to the observed excellent kinetic resolution efficiency. This photochemical transformation expands the potential of kinetic resolution beyond their established ground-state reactivity, furnishing a novel reaction mode for enantioselective catalysis at its excited state.
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Affiliation(s)
- Hao Zhang
- State Key Laboratory of Analytical Chemistry for Life Science, Jiangsu Key Laboratory of Advanced Organic Materials, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Congcong Huang
- School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, China
| | - Xiang-Ai Yuan
- School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, China
| | - Shouyun Yu
- State Key Laboratory of Analytical Chemistry for Life Science, Jiangsu Key Laboratory of Advanced Organic Materials, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
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17
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Del Vecchio A, Sinibaldi A, Nori V, Giorgianni G, Di Carmine G, Pesciaioli F. Synergistic Strategies in Aminocatalysis. Chemistry 2022; 28:e202200818. [PMID: 35666172 PMCID: PMC9539941 DOI: 10.1002/chem.202200818] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Indexed: 12/20/2022]
Abstract
Synergistic catalysis offers the unique possibility of simultaneous activation of both the nucleophile and the electrophile in a reaction. A requirement for this strategy is the stability of the active species towards the reaction conditions and the two concerted catalytic cycles. Since the beginning of the century, aminocatalysis has been established as a platform for the stereoselective activation of carbonyl compounds through HOMO‐raising or LUMO‐lowering. The burgeoning era of aminocatalysis has been driven by a deep understanding of these activation and stereoinduction modes, thanks to the introduction of versatile and privileged chiral amines. The aim of this review is to cover recent developments in synergistic strategies involving aminocatalysis in combination with organo‐, metal‐, photo‐, and electro‐catalysis, focusing on the evolution of privileged aminocatalysts architectures.
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Affiliation(s)
- Antonio Del Vecchio
- Department of Physical and Chemical Sciences Università degli Studi, dell'Aquila, via Vetoio, 67100, L'Aquila, Italy
| | - Arianna Sinibaldi
- Department of Physical and Chemical Sciences Università degli Studi, dell'Aquila, via Vetoio, 67100, L'Aquila, Italy
| | - Valeria Nori
- Department of Physical and Chemical Sciences Università degli Studi, dell'Aquila, via Vetoio, 67100, L'Aquila, Italy
| | - Giuliana Giorgianni
- Department of Physical and Chemical Sciences Università degli Studi, dell'Aquila, via Vetoio, 67100, L'Aquila, Italy
| | - Graziano Di Carmine
- Department of Chemical, Pharmaceutical and Agricultural Sciences Università degli Studi di Ferrara, Via Fossato di Mortara 17, 44121, Ferrara, Italy
| | - Fabio Pesciaioli
- Department of Physical and Chemical Sciences Università degli Studi, dell'Aquila, via Vetoio, 67100, L'Aquila, Italy
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18
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Reek JNH, de Bruin B, Pullen S, Mooibroek TJ, Kluwer AM, Caumes X. Transition Metal Catalysis Controlled by Hydrogen Bonding in the Second Coordination Sphere. Chem Rev 2022; 122:12308-12369. [PMID: 35593647 PMCID: PMC9335700 DOI: 10.1021/acs.chemrev.1c00862] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Transition metal catalysis is of utmost importance for the development of sustainable processes in academia and industry. The activity and selectivity of metal complexes are typically the result of the interplay between ligand and metal properties. As the ligand can be chemically altered, a large research focus has been on ligand development. More recently, it has been recognized that further control over activity and selectivity can be achieved by using the "second coordination sphere", which can be seen as the region beyond the direct coordination sphere of the metal center. Hydrogen bonds appear to be very useful interactions in this context as they typically have sufficient strength and directionality to exert control of the second coordination sphere, yet hydrogen bonds are typically very dynamic, allowing fast turnover. In this review we have highlighted several key features of hydrogen bonding interactions and have summarized the use of hydrogen bonding to program the second coordination sphere. Such control can be achieved by bridging two ligands that are coordinated to a metal center to effectively lead to supramolecular bidentate ligands. In addition, hydrogen bonding can be used to preorganize a substrate that is coordinated to the metal center. Both strategies lead to catalysts with superior properties in a variety of metal catalyzed transformations, including (asymmetric) hydrogenation, hydroformylation, C-H activation, oxidation, radical-type transformations, and photochemical reactions.
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Affiliation(s)
- Joost N H Reek
- Homogeneous and Supramolecular Catalysis, Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.,InCatT B.V., Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Bas de Bruin
- Homogeneous and Supramolecular Catalysis, Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Sonja Pullen
- Homogeneous and Supramolecular Catalysis, Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Tiddo J Mooibroek
- Homogeneous and Supramolecular Catalysis, Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | | | - Xavier Caumes
- InCatT B.V., Science Park 904, 1098 XH Amsterdam, The Netherlands
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19
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Takagi R, Tanimoto T. Enantioselective [2 + 2] photocycloaddition of quinolone using a C1-symmetric chiral phosphoric acid as a visible-light photocatalyst. Org Biomol Chem 2022; 20:3940-3947. [PMID: 35506886 DOI: 10.1039/d2ob00607c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The enantioselective intra- and intermolecular [2 + 2] photocycloaddition of quinolone using a C1-symmetric chiral phosphoric acid as a visible-light photocatalyst is developed. The thioxanthone chromophore on phosphoric acid plays an important role in both phototransformation and enantioselectivity.
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Affiliation(s)
- Ryukichi Takagi
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan.
| | - Takaaki Tanimoto
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan.
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20
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Liu YQ, Li QZ, Kou XX, Zeng R, Qi T, Zhang X, Peng C, Han B, Li JL. Radical Acylalkylation of 1,3-Enynes To Access Allenic Ketones via N-Heterocyclic Carbene Organocatalysis. J Org Chem 2022; 87:5229-5241. [DOI: 10.1021/acs.joc.2c00037] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Yan-Qing Liu
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, P. R. China
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, School of Pharmacy, Chengdu University, Chengdu 610106, P. R. China
| | - Qing-Zhu Li
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, School of Pharmacy, Chengdu University, Chengdu 610106, P. R. China
| | - Xin-Xin Kou
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, School of Pharmacy, Chengdu University, Chengdu 610106, P. R. China
| | - Rong Zeng
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, School of Pharmacy, Chengdu University, Chengdu 610106, P. R. China
| | - Ting Qi
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, School of Pharmacy, Chengdu University, Chengdu 610106, P. R. China
| | - Xiang Zhang
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, School of Pharmacy, Chengdu University, Chengdu 610106, P. R. China
| | - Cheng Peng
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, P. R. China
| | - Bo Han
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, P. R. China
| | - Jun-Long Li
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, P. R. China
- Antibiotics Research and Re-evaluation Key Laboratory of Sichuan Province, Sichuan Industrial Institute of Antibiotics, School of Pharmacy, Chengdu University, Chengdu 610106, P. R. China
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21
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Huang M, Zhang L, Pan T, Luo S. Deracemization through photochemical E/ Z isomerization of enamines. Science 2022; 375:869-874. [PMID: 35201874 DOI: 10.1126/science.abl4922] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Catalytic deracemization of α-branched aldehydes is a direct strategy to construct enantiopure α-tertiary carbonyls, which are essential to pharmaceutical applications. Here, we report a photochemical E/Z isomerization strategy for the deracemization of α-branched aldehydes by using simple aminocatalysts and readily available photosensitizers. A variety of racemic α-branched aldehydes could be directly transformed into either enantiomer with high selectivity. Rapid photodynamic E/Z isomerization and highly stereospecific iminium/enamine tautomerization are two key factors that underlie the enantioenrichment. This study presents a distinctive photochemical E/Z isomerization strategy for externally tuning enamine catalysis.
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Affiliation(s)
- Mouxin Huang
- Center of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Long Zhang
- Center of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100084, China.,Haihe Laboratory of Sustainable Chemical Transformations, Tianjin 300192, China
| | - Tianrun Pan
- Center of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Sanzhong Luo
- Center of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100084, China.,Haihe Laboratory of Sustainable Chemical Transformations, Tianjin 300192, China
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22
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Genzink MJ, Kidd JB, Swords WB, Yoon TP. Chiral Photocatalyst Structures in Asymmetric Photochemical Synthesis. Chem Rev 2022; 122:1654-1716. [PMID: 34606251 PMCID: PMC8792375 DOI: 10.1021/acs.chemrev.1c00467] [Citation(s) in RCA: 129] [Impact Index Per Article: 64.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Asymmetric catalysis is a major theme of research in contemporary synthetic organic chemistry. The discovery of general strategies for highly enantioselective photochemical reactions, however, has been a relatively recent development, and the variety of photoreactions that can be conducted in a stereocontrolled manner is consequently somewhat limited. Asymmetric photocatalysis is complicated by the short lifetimes and high reactivities characteristic of photogenerated reactive intermediates; the design of catalyst architectures that can provide effective enantiodifferentiating environments for these intermediates while minimizing the participation of uncontrolled racemic background processes has proven to be a key challenge for progress in this field. This review provides a summary of the chiral catalyst structures that have been studied for solution-phase asymmetric photochemistry, including chiral organic sensitizers, inorganic chromophores, and soluble macromolecules. While some of these photocatalysts are derived from privileged catalyst structures that are effective for both ground-state and photochemical transformations, others are structural designs unique to photocatalysis and offer insight into the logic required for highly effective stereocontrolled photocatalysis.
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Affiliation(s)
- Matthew J Genzink
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Jesse B Kidd
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Wesley B Swords
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Tehshik P Yoon
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
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23
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Su Y, Zou Y, Xiao W. Recent Advances in Photocatalytic Deracemization. CHINESE J ORG CHEM 2022. [DOI: 10.6023/cjoc202207046] [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]
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24
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Rai P, Maji K, Jana SK, Maji B. Intermolecular dearomative [4 + 2] cycloaddition of naphthalenes via visible-light energy-transfer-catalysis. Chem Sci 2022; 13:12503-12510. [PMID: 36349268 PMCID: PMC9628934 DOI: 10.1039/d2sc04005k] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 10/04/2022] [Indexed: 11/28/2022] Open
Abstract
The dearomative cycloaddition reaction serves as a blueprint for creating sp3-rich three-dimensional molecular topology from flat-aromatic compounds. However, severe reactivity and selectivity issues make this process arduous. Herein, we describe visible-light energy-transfer catalysis for the intermolecular dearomative [4 + 2] cycloaddition reaction of feedstock naphthalene molecules with vinyl benzenes. Tolerating a wide range of functional groups, structurally diverse 2-acyl naphthalenes and styrenes could easily be converted to a diverse range of bicyclo[2.2.2]octa-2,5-diene scaffolds in high yields and moderate endo-selectivities. The late-stage modification of the derivatives of pharmaceutical agents further demonstrated the broad potentiality of this methodology. The efficacy of the introduced methods was further highlighted by the post-synthetic diversification of the products. Furthermore, photoluminescence, electrochemical, kinetic, control experiments, and density-functional theory calculations support energy-transfer catalysis. Constructing 3D molecular scaffolds from aromatic hydrocarbons is challenging. Herein, we report dearomative [4 + 2] cycloaddition reaction of naphthalenes via visible-light EnT catalysis which overcomes issues of unfavorable thermodynamics, low yields, and selectivity.![]()
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Affiliation(s)
- Pramod Rai
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, WB, India
| | - Kakoli Maji
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, WB, India
| | - Sayan K. Jana
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, WB, India
| | - Biplab Maji
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, WB, India
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25
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Reactivity and selectivity modulation within a molecular assembly: recent examples from photochemistry. Photochem Photobiol Sci 2021; 21:719-737. [PMID: 34914081 PMCID: PMC9174329 DOI: 10.1007/s43630-021-00146-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 11/17/2021] [Indexed: 12/05/2022]
Abstract
In recent years, photochemical reactions have emerged as powerful transformations which significantly expand the repertoire of organic synthesis. However, a certain lack of selectivity can hamper their application and limit their scope. In this context, a major research effort continues to focus on an improved control over stereo- and chemoselectivity that can be achieved in molecular assemblies between photosubstrates and an appropriate host molecule. In this tutorial review, some recent, representative examples of photochemical reactions have been collected whose unique outcome is dictated by the formation of a molecular assembly driven by non-covalent weak interactions.
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26
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Zhang Z, Hu X. Visible-Light-Driven Catalytic Deracemization of Secondary Alcohols. Angew Chem Int Ed Engl 2021; 60:22833-22838. [PMID: 34397164 PMCID: PMC8519112 DOI: 10.1002/anie.202107570] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/14/2021] [Indexed: 11/18/2022]
Abstract
Deracemization of racemic chiral compounds is an attractive approach in asymmetric synthesis, but its development has been hindered by energetic and kinetic challenges. Here we describe a catalytic deracemization method for secondary benzylic alcohols which are important synthetic intermediates and end products for many industries. Driven by visible light only, this method is based on sequential photochemical dehydrogenation followed by enantioselective thermal hydrogenation. The combination of a heterogeneous dehydrogenation photocatalyst and a chiral molecular hydrogenation catalyst is essential to ensure two distinct pathways for the forward and reverse reactions. These reactions convert a large number of racemic aryl alkyl alcohols into their enantiomerically enriched forms in good yields and enantioselectivities.
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Affiliation(s)
- Zhikun Zhang
- Laboratory of Inorganic Synthesis and CatalysisInstitute of Chemical Sciences and EngineeringEcole Poly-technique Fédérale de Lausanne (EPFL)ISIC-LSCI, BCH 3305Lausanne1015Switzerland
| | - Xile Hu
- Laboratory of Inorganic Synthesis and CatalysisInstitute of Chemical Sciences and EngineeringEcole Poly-technique Fédérale de Lausanne (EPFL)ISIC-LSCI, BCH 3305Lausanne1015Switzerland
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27
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Zhang Z, Hu X. Visible‐Light‐Driven Catalytic Deracemization of Secondary Alcohols. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202107570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Zhikun Zhang
- Laboratory of Inorganic Synthesis and Catalysis Institute of Chemical Sciences and Engineering Ecole Poly-technique Fédérale de Lausanne (EPFL) ISIC-LSCI, BCH 3305 Lausanne 1015 Switzerland
| | - Xile Hu
- Laboratory of Inorganic Synthesis and Catalysis Institute of Chemical Sciences and Engineering Ecole Poly-technique Fédérale de Lausanne (EPFL) ISIC-LSCI, BCH 3305 Lausanne 1015 Switzerland
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28
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Zhang C, Gao AZ, Nie X, Ye CX, Ivlev SI, Chen S, Meggers E. Catalytic α-Deracemization of Ketones Enabled by Photoredox Deprotonation and Enantioselective Protonation. J Am Chem Soc 2021; 143:13393-13400. [PMID: 34392683 DOI: 10.1021/jacs.1c06637] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
This study reports the catalytic deracemization of ketones bearing stereocenters in the α-position in a single reaction via deprotonation, followed by enantioselective protonation. The principle of microscopic reversibility, which has previously rendered this strategy elusive, is overcome by a photoredox deprotonation through single electron transfer and subsequent hydrogen atom transfer (HAT). Specifically, the irradiation of racemic pyridylketones in the presence of a single photocatalyst and a tertiary amine provides nonracemic carbonyl compounds with up to 97% enantiomeric excess. The photocatalyst harvests the visible light, induces the redox process, and is responsible for the asymmetric induction, while the amine serves as a single electron donor, HAT reagent, and proton source. This conceptually simple light-driven strategy of coupling a photoredox deprotonation with a stereocontrolled protonation, in conjunction with an enrichment process, serves as a blueprint for other deracemizations of ubiquitous carbonyl compounds.
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Affiliation(s)
- Chenhao Zhang
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35043 Marburg, Germany
| | - Anthony Z Gao
- Department of Chemistry and Biochemistry, Oberlin College, Oberlin, Ohio 44074, United States
| | - Xin Nie
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35043 Marburg, Germany
| | - Chen-Xi Ye
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35043 Marburg, Germany
| | - Sergei I Ivlev
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35043 Marburg, Germany
| | - Shuming Chen
- Department of Chemistry and Biochemistry, Oberlin College, Oberlin, Ohio 44074, United States
| | - Eric Meggers
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35043 Marburg, Germany
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29
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Plaza M, Großkopf J, Breitenlechner S, Bannwarth C, Bach T. Photochemical Deracemization of Primary Allene Amides by Triplet Energy Transfer: A Combined Synthetic and Theoretical Study. J Am Chem Soc 2021; 143:11209-11217. [PMID: 34279085 DOI: 10.1021/jacs.1c05286] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The photochemical deracemization of 2,4-disubstituted 2,3-butadienamides (allene amides) was investigated both experimentally and theoretically. The reaction was catalyzed by a thioxanthone which is covalently linked to a chiral 1,5,7-trimethyl-3-azabicyclo[3.3.1]nonan-2-one skeleton providing a U-shaped arrangement of the sensitizing unit relative to a potential hydrogen-bonding site. Upon irradiation at λ = 420 nm in the presence of the sensitizer (2.5 mol %), the amides reached at -10 °C a photostationary state in which one enantiomer prevailed. The enantioenriched allene amides (70-93% ee) were isolated in 74% to quantitative yield (19 examples). Based on luminescence data and DFT calculations, energy transfer from the thioxanthone to the allene amides is thermodynamically feasible, and the achiral triplet allene intermediate was structurally characterized. Hydrogen bonding of the amide enantiomers to the sensitizer was monitored by NMR titration. The experimental association constants (Ka) were similar (59.8 vs 25.7 L·mol-1). DFT calculations, however, revealed a significant difference in the binding properties of the two enantiomers. The major product enantiomer exhibits a noncovalent dispersion interaction of its arylmethyl group to the external benzene ring of the thioxanthone, thus moving away the allene from the carbonyl chromophore. The minor enantiomer displays a CH-π interaction of the hydrogen atom at the terminal allene carbon atom to the same benzene ring, thus forcing the allene into close proximity to the chromophore. The binding behavior explains the observed enantioselectivity which, as corroborated by additional calculations, is due to a rapid triplet energy transfer within the substrate-catalyst complex of the minor enantiomer.
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Affiliation(s)
- Manuel Plaza
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, D-85747 Garching, Germany
| | - Johannes Großkopf
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, D-85747 Garching, Germany
| | - Stefan Breitenlechner
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, D-85747 Garching, Germany
| | - Christoph Bannwarth
- Institute of Physical Chemistry, RWTH Aachen University, D-52056 Aachen, Germany
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, D-85747 Garching, Germany
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30
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Großkopf J, Kratz T, Rigotti T, Bach T. Enantioselective Photochemical Reactions Enabled by Triplet Energy Transfer. Chem Rev 2021; 122:1626-1653. [PMID: 34227803 DOI: 10.1021/acs.chemrev.1c00272] [Citation(s) in RCA: 137] [Impact Index Per Article: 45.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
For molecules with a singlet ground state, the population of triplet states is mainly possible (a) by direct excitation and subsequent intersystem crossing or (b) by energy transfer from an appropriate sensitizer. The latter scenario enables a catalytic photochemical reaction in which the sensitizer adopts the role of a catalyst undergoing several cycles of photon absorption and subsequent energy transfer to the substrate. If the product molecule of a triplet-sensitized process is chiral, this process can proceed enantioselectively upon judicious choice of a chiral triplet sensitizer. An enantioselective reaction can also occur in a dual catalytic approach in which, apart from an achiral sensitizer, a second chiral catalyst activates the substrate toward sensitization. Although the idea of enantioselective photochemical reactions via triplet intermediates has been pursued for more than 50 years, notable selectivities exceeding 90% enantiomeric excess (ee) have only been realized in the past decade. This review attempts to provide a comprehensive survey on the various photochemical reactions which were rendered enantioselective by triplet sensitization.
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Affiliation(s)
- Johannes Großkopf
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, D-85747 Garching, Germany
| | - Thilo Kratz
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, D-85747 Garching, Germany
| | - Thomas Rigotti
- 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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31
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Liu J, Wei Y, Shi M. Direct Activation of a Remote C(sp 3 )-H Bond Enabled by a Visible-Light Photosensitized Allene Moiety. Angew Chem Int Ed Engl 2021; 60:12053-12059. [PMID: 33719146 DOI: 10.1002/anie.202101266] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 03/02/2021] [Indexed: 12/14/2022]
Abstract
Despite allene derivatives have been always regarded as a radical accepter in traditional radical chemistry for decades, the reactivity of allene derivatives under excited state in radical chemistry was rarely explored. Herein, we wish to report an example to engage triplet-excited state of allene moiety as hydrogen-atom-transfer (HAT) partner in the activation of remote sp3 C-H bond via visible-light irradiation under mild reaction conditions with broad substrate scope and good functional-group tolerance. The reaction mechanism involving the generation of triplet excited state of allene derivative and the subsequent HAT process was supported by deuterium labeling, kinetic analysis experiments and DFT calculations.
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Affiliation(s)
- Jiaxin Liu
- State Key Laboratory of Organometallic Chemistry, University of Chinese Academy of Sciences, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, China
| | - Yin Wei
- State Key Laboratory of Organometallic Chemistry, University of Chinese Academy of Sciences, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, China
| | - Min Shi
- State Key Laboratory of Organometallic Chemistry, University of Chinese Academy of Sciences, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, China
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32
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Liu J, Wei Y, Shi M. Direct Activation of a Remote C(sp
3
)–H Bond Enabled by a Visible‐Light Photosensitized Allene Moiety. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202101266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Jiaxin Liu
- State Key Laboratory of Organometallic Chemistry University of Chinese Academy of Sciences Center for Excellence in Molecular Synthesis Shanghai Institute of Organic Chemistry Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
| | - Yin Wei
- State Key Laboratory of Organometallic Chemistry University of Chinese Academy of Sciences Center for Excellence in Molecular Synthesis Shanghai Institute of Organic Chemistry Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
| | - Min Shi
- State Key Laboratory of Organometallic Chemistry University of Chinese Academy of Sciences Center for Excellence in Molecular Synthesis Shanghai Institute of Organic Chemistry Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China
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33
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Li X, Großkopf J, Jandl C, Bach T. Enantioselective, Visible Light Mediated Aza Paternò–Büchi Reactions of Quinoxalinones. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202013276] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Xinyao Li
- Department Chemie and Catalysis Research Center (CRC) Technische Universität München Lichtenbergstrasse 4 85747 Garching Germany
| | - Johannes Großkopf
- Department Chemie and Catalysis Research Center (CRC) Technische Universität München Lichtenbergstrasse 4 85747 Garching Germany
| | - Christian Jandl
- Department Chemie and Catalysis Research Center (CRC) Technische Universität München Lichtenbergstrasse 4 85747 Garching Germany
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC) Technische Universität München Lichtenbergstrasse 4 85747 Garching Germany
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34
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Buhse T, Cruz JM, Noble-Terán ME, Hochberg D, Ribó JM, Crusats J, Micheau JC. Spontaneous Deracemizations. Chem Rev 2021; 121:2147-2229. [DOI: 10.1021/acs.chemrev.0c00819] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Thomas Buhse
- Centro de Investigaciones Químicas−IICBA, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, 62209 Cuernavaca, Morelos Mexico
| | - José-Manuel Cruz
- Facultad de Ciencias en Física y Matemáticas, Universidad Autónoma de Chiapas, Tuxtla Gutiérrez, Chiapas 29050, Mexico
| | - María E. Noble-Terán
- Centro de Investigaciones Químicas−IICBA, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, 62209 Cuernavaca, Morelos Mexico
| | - David Hochberg
- Department of Molecular Evolution, Centro de Astrobiología (CSIC-INTA), Carretera Ajalvir, Km. 4, 28850 Torrejón de Ardoz, Madrid Spain
| | - Josep M. Ribó
- Institut de Ciències del Cosmos (IEEC-ICC) and Departament de Química Inorgànica i Orgànica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Catalunya Spain
| | - Joaquim Crusats
- Institut de Ciències del Cosmos (IEEC-ICC) and Departament de Química Inorgànica i Orgànica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Catalunya Spain
| | - Jean-Claude Micheau
- Laboratoire des IMRCP, UMR au CNRS No. 5623, Université Paul Sabatier, F-31062 Toulouse Cedex, France
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35
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Zhou TP, Zhong F, Wu Y, Liao RZ. Regioselectivity and stereoselectivity of intramolecular [2 + 2] photocycloaddition catalyzed by chiral thioxanthone: a quantum chemical study. Org Biomol Chem 2021; 19:1532-1540. [DOI: 10.1039/d0ob02330b] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Chiral photosensitizer-catalyzed stereoselective olefin cyclization has shown its significance in organic synthesis.
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Affiliation(s)
- Tai-Ping Zhou
- Key Laboratory of Materials Chemistry for Energy Conversion and Storage
- Ministry of Education
- Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica
- Hubei Key Laboratory of Materials Chemistry and Service Failure
- School of Chemistry and Chemical Engineering
| | - Fangrui Zhong
- Key Laboratory of Materials Chemistry for Energy Conversion and Storage
- Ministry of Education
- Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica
- Hubei Key Laboratory of Materials Chemistry and Service Failure
- School of Chemistry and Chemical Engineering
| | - Yuzhou Wu
- Key Laboratory of Materials Chemistry for Energy Conversion and Storage
- Ministry of Education
- Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica
- Hubei Key Laboratory of Materials Chemistry and Service Failure
- School of Chemistry and Chemical Engineering
| | - Rong-Zhen Liao
- Key Laboratory of Materials Chemistry for Energy Conversion and Storage
- Ministry of Education
- Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica
- Hubei Key Laboratory of Materials Chemistry and Service Failure
- School of Chemistry and Chemical Engineering
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36
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Li X, Großkopf J, Jandl C, Bach T. Enantioselective, Visible Light Mediated Aza Paternò-Büchi Reactions of Quinoxalinones. Angew Chem Int Ed Engl 2020; 60:2684-2688. [PMID: 33084097 PMCID: PMC7898282 DOI: 10.1002/anie.202013276] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Indexed: 02/04/2023]
Abstract
3-Substituted quinoxalin-2(1H)-ones and various aryl-substituted or tethered olefins underwent an enantioselective, inter- or intramolecular aza Paternò-Büchi reaction upon irradiation at λ=420 nm in the presence of a chiral sensitizer (10 mol %). For the intermolecular reaction with 1-arylethenes as olefin components, the scope of the reaction was studied (14 examples, 50-99 % yield, 86-98 % ee). The absolute and relative configuration of the products were elucidated by single-crystal X-ray crystallography. The reaction is suggested to occur by triplet energy transfer in a hydrogen-bonded 1:1 complex between the imine substrate and the catalyst. The intramolecular cycloaddition, consecutive reactions of the product azetidines, and an alternative reaction mode of quinoxalinones were investigated in preliminary experiments.
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Affiliation(s)
- Xinyao Li
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstrasse 4, 85747, Garching, Germany
| | - Johannes Großkopf
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstrasse 4, 85747, Garching, Germany
| | - Christian Jandl
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstrasse 4, 85747, Garching, Germany
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstrasse 4, 85747, Garching, Germany
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37
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Li X, Kutta RJ, Jandl C, Bauer A, Nuernberger P, Bach T. Photochemically Induced Ring Opening of Spirocyclopropyl Oxindoles: Evidence for a Triplet 1,3‐Diradical Intermediate and Deracemization by a Chiral Sensitizer. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202008384] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Xinyao Li
- Department Chemie and Catalysis Research Center (CRC) Technische Universität München Lichtenbergstraße 4 85747 Garching Germany
| | - Roger J. Kutta
- Institut für Physikalische und Theoretische Chemie Universität Regensburg Universitätsstr. 31 93053 Regensburg Germany
| | - Christian Jandl
- Department Chemie and Catalysis Research Center (CRC) Technische Universität München Lichtenbergstraße 4 85747 Garching Germany
| | - Andreas Bauer
- Department Chemie and Catalysis Research Center (CRC) Technische Universität München Lichtenbergstraße 4 85747 Garching Germany
| | - Patrick Nuernberger
- Institut für Physikalische und Theoretische Chemie Universität Regensburg Universitätsstr. 31 93053 Regensburg Germany
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC) Technische Universität München Lichtenbergstraße 4 85747 Garching Germany
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38
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Prentice C, Morrisson J, Smith AD, Zysman-Colman E. Recent developments in enantioselective photocatalysis. Beilstein J Org Chem 2020; 16:2363-2441. [PMID: 33082877 PMCID: PMC7537410 DOI: 10.3762/bjoc.16.197] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 09/09/2020] [Indexed: 01/02/2023] Open
Abstract
Enantioselective photocatalysis has rapidly grown into a powerful tool for synthetic chemists. This review describes the various strategies for creating enantioenriched products through merging enantioselective catalysis and photocatalysis, with a focus on the most recent developments and a particular interest in the proposed mechanisms for each. With the aim of understanding the scope of each strategy, to help guide and inspire further innovation in this field.
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Affiliation(s)
- Callum Prentice
- Organic Semiconductor Centre, EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, Fife, Scotland, KY16 9ST, United Kingdom
| | - James Morrisson
- Pharmaceutical Sciences, IMED Biotech Unit, AstraZeneca, Macclesfield SK102NA, United Kingdom
| | - Andrew D Smith
- Organic Semiconductor Centre, EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, Fife, Scotland, KY16 9ST, United Kingdom
| | - Eli Zysman-Colman
- Organic Semiconductor Centre, EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, Fife, Scotland, KY16 9ST, United Kingdom
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39
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Li X, Kutta RJ, Jandl C, Bauer A, Nuernberger P, Bach T. Photochemically Induced Ring Opening of Spirocyclopropyl Oxindoles: Evidence for a Triplet 1,3-Diradical Intermediate and Deracemization by a Chiral Sensitizer. Angew Chem Int Ed Engl 2020; 59:21640-21647. [PMID: 32757341 PMCID: PMC7756555 DOI: 10.1002/anie.202008384] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 07/23/2020] [Indexed: 12/17/2022]
Abstract
The photochemical deracemization of spiro[cyclopropane‐1,3′‐indolin]‐2′‐ones (spirocyclopropyl oxindoles) was studied. The corresponding 2,2‐dichloro compound is configurationally labile upon direct irradiation at λ=350 nm and upon irradiation at λ=405 nm in the presence of achiral thioxanthen‐9‐one as the sensitizer. The triplet 1,3‐diradical intermediate generated in the latter reaction was detected by transient absorption spectroscopy and its lifetime determined (τ=22 μs). Using a chiral thioxanthone or xanthone, with a lactam hydrogen bonding site as a photosensitizer, allowed the deracemization of differently substituted chiral spirocyclopropyl oxindoles with yields of 65–98 % and in 50–85 % ee (17 examples). Three mechanistic contributions were identified to co‐act favorably for high enantioselectivity: the difference in binding constants to the chiral thioxanthone, the smaller molecular distance in the complex of the minor enantiomer, and the lifetime of the intermediate 1,3‐diradical.
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Affiliation(s)
- Xinyao Li
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstraße 4, 85747, Garching, Germany
| | - Roger J Kutta
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Christian Jandl
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstraße 4, 85747, Garching, Germany
| | - Andreas Bauer
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstraße 4, 85747, Garching, Germany
| | - Patrick Nuernberger
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstraße 4, 85747, Garching, Germany
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40
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Plaza M, Jandl C, Bach T. Photochemical Deracemization of Allenes and Subsequent Chirality Transfer. Angew Chem Int Ed Engl 2020; 59:12785-12788. [PMID: 32390291 PMCID: PMC7537568 DOI: 10.1002/anie.202004797] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Indexed: 12/29/2022]
Abstract
Trisubstituted allenes with a 3-(1'-alkenylidene)-pyrrolidin-2-one motif were successfully deracemized (13 examples, 86-98 % ee) employing visible light (λ=420 nm) and a chiral triplet sensitizer as the catalyst (2.5 mol %). The photocatalyst likely operates by selective recognition of one allene enantiomer via hydrogen bonds and by a triplet-sensitized racemization process. Even a tetrasubstituted allene (45 % ee) and a seven-membered 3-(1'-alkenylidene)-azepan-2-one (62 % ee) could be enantiomerically enriched under the chosen conditions. It was shown that the axial chirality of the allenes can be converted into point chirality by a Diels-Alder (94-97 % ee) or a bromination reaction (91 % ee). Ring opening of the five-membered pyrrolidin-2-one was achieved without significantly compromising the integrity of the chirality axis (92 % ee).
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Affiliation(s)
- Manuel Plaza
- Department Chemie and Catalysis Research Center (CRC)Technische Universität MünchenLichtenbergstrasse 485747GarchingGermany
| | - Christian Jandl
- Department Chemie and Catalysis Research Center (CRC)Technische Universität MünchenLichtenbergstrasse 485747GarchingGermany
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC)Technische Universität MünchenLichtenbergstrasse 485747GarchingGermany
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41
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Rigotti T, Alemán J. Visible light photocatalysis – from racemic to asymmetric activation strategies. Chem Commun (Camb) 2020; 56:11169-11190. [DOI: 10.1039/d0cc03738a] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The most significant contributions towards enantioselective photocatalysis have been described with a special emphasis on the various activation strategies.
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Affiliation(s)
- Thomas Rigotti
- Organic Chemistry Department
- Universidad Autónoma de Madrid
- 28049 Madrid
- Spain
| | - José Alemán
- Organic Chemistry Department
- Universidad Autónoma de Madrid
- 28049 Madrid
- Spain
- Institute for Advanced Research in Chemical Sciences (IAdChem)
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