1
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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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2
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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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3
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Xu Y, Dong G. Deracemization through C-C bond manipulation. Sci Bull (Beijing) 2024; 69:285-287. [PMID: 38105162 DOI: 10.1016/j.scib.2023.12.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Affiliation(s)
- Yan Xu
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
| | - Guangbin Dong
- Department of Chemistry, University of Chicago, Chicago IL 60637, USA.
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4
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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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5
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Großkopf J, Plaza M, Kutta RJ, Nuernberger P, Bach T. Creating a Defined Chirality in Amino Acids and Cyclic Dipeptides by Photochemical Deracemization. Angew Chem Int Ed Engl 2023; 62:e202313606. [PMID: 37793026 DOI: 10.1002/anie.202313606] [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: 09/13/2023] [Revised: 09/30/2023] [Accepted: 10/02/2023] [Indexed: 10/06/2023]
Abstract
2,5-Diketopiperazines are cyclic dipeptides displaying a wide range of applications. Their enantioselective preparation has now been found possible from the respective racemates by a photochemical deracemization (53 examples, 74 % to quantitative yield, 71-99 % ee). A chiral benzophenone catalyst in concert with irradiation at λ=366 nm enables to establish the configuration at the stereogenic carbon atom C6 at will. If other stereogenic centers are present in the diketopiperazines they remain unaffected and a stereochemical editing is possible at a single position. Consecutive reactions, including the conversion into N-aryl or N-alkyl amino acids or the reduction to piperazines, occur without compromising the newly created stereogenic center. Transient absorption spectroscopy revealed that the benzophenone catalyst processes one enantiomer of the 2,5-diketopiperazines preferentially and enables a reversible hydrogen atom transfer that is responsible for the deracemization process. The remarkably long lifetime of the protonated ketyl radical implies a yet unprecedented mode of action.
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Affiliation(s)
- Johannes Großkopf
- Department Chemie and Catalysis Research Center (CRC), School of Natural Sciences, Technische Universität München, D-85747, Garching, Germany
| | - Manuel Plaza
- Department Chemie and Catalysis Research Center (CRC), School of Natural Sciences, Technische Universität München, D-85747, Garching, Germany
| | - Roger Jan Kutta
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, Universitätsstr. 31, D-93053, Regensburg, Germany
| | - Patrick Nuernberger
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, Universitätsstr. 31, D-93053, Regensburg, Germany
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC), School of Natural Sciences, Technische Universität München, D-85747, Garching, Germany
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6
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Wen L, Ding J, Duan L, Wang S, An Q, Wang H, Zuo Z. Multiplicative enhancement of stereoenrichment by a single catalyst for deracemization of alcohols. Science 2023; 382:458-464. [PMID: 37883537 DOI: 10.1126/science.adj0040] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 09/04/2023] [Indexed: 10/28/2023]
Abstract
Stereochemical enrichment of a racemic mixture by deracemization must overcome unfavorable entropic effects as well as the principle of microscopic reversibility; recently, photochemical reaction pathways unveiled by the energetic input of light have led to innovations toward this end, most often by ablation of a stereogenic C(sp3)-H bond. We report a photochemically driven deracemization protocol in which a single chiral catalyst effects two mechanistically different steps, C-C bond cleavage and C-C bond formation, to achieve multiplicative enhancement of stereoinduction, which leads to high levels of stereoselectivity. Ligand-to-metal charge transfer excitation of a titanium catalyst coordinated by a chiral phosphoric acid or bisoxazoline efficiently enriches racemic alcohols that feature adjacent and fully substituted stereogenic centers to enantiomeric ratios up to 99:1. Mechanistic investigations support a pathway of sequential radical-mediated bond scission and bond formation through a common prochiral intermediate and reveal that, although the overall stereoenrichment is high, the selectivity in each individual step is moderate.
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Affiliation(s)
- Lu Wen
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Jia Ding
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Lingfei Duan
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Shun Wang
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Qing An
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Hexiang Wang
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Zhiwei Zuo
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200032, China
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7
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Chen Q, Zhu Y, Shi X, Huang R, Jiang C, Zhang K, Liu G. Light-driven redox deracemization of indolines and tetrahydroquinolines using a photocatalyst coupled with chiral phosphoric acid. Chem Sci 2023; 14:1715-1723. [PMID: 36819858 PMCID: PMC9930931 DOI: 10.1039/d2sc06340a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 01/09/2023] [Indexed: 01/11/2023] Open
Abstract
The integration of oxidation and enantioselective reduction enables a redox deracemization to directly access enantioenriched products from their corresponding racemates. However, the solution of the kinetically microscopic reversibility of substrates used in this oxidation/reduction unidirectional event is a great challenge. To address this issue, we have developed a light-driven strategy to enable an efficient redox deracemization of cyclamines. The method combines a photocatalyst and a chiral phosphoric acid in a toluene/aqueous cyclodextrin emulsion biphasic co-solvent system to drive the cascade out-of-equilibrium. Systemic optimizations achieve a feasible oxidation/reduction cascade sequence, and mechanistic investigations demonstrate a unidirectional process. This single-operation cascade route, which involves initial photocatalyzed oxidation of achiral cyclamines to cyclimines and subsequent chiral phosphoric acid-catalyzed enantioselective reduction of cyclimines to chiral cyclamines, is suitable for constructing optically pure indolines and tetrahydroquinolines.
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Affiliation(s)
- Qipeng Chen
- International Joint Laboratory on Resource Chemistry of Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University Shanghai 200234 P. R. China
| | - Yuanli Zhu
- International Joint Laboratory on Resource Chemistry of Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University Shanghai 200234 P. R. China
| | - Xujing Shi
- International Joint Laboratory on Resource Chemistry of Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University Shanghai 200234 P. R. China
| | - Renfu Huang
- International Joint Laboratory on Resource Chemistry of Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University Shanghai 200234 P. R. China
| | - Chuang Jiang
- International Joint Laboratory on Resource Chemistry of Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University Shanghai 200234 P. R. China
| | - Kun Zhang
- International Joint Laboratory on Resource Chemistry of Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University Shanghai 200234 P. R. China
| | - Guohua Liu
- International Joint Laboratory on Resource Chemistry of Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University Shanghai 200234 P. R. China
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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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Kim M, Hong S, Jeong J, Hong S. Visible-Light-Active Coumarin- and Quinolinone-Based Photocatalysts and Their Applications in Chemical Transformations. CHEM REC 2023:e202200267. [PMID: 36627191 DOI: 10.1002/tcr.202200267] [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: 11/28/2022] [Revised: 12/16/2022] [Indexed: 01/12/2023]
Abstract
Organic dyes have been actively studied as useful photocatalysts because they allow access to versatile structural flexibility and green synthetic applications. The identification of a new class of robust organic chromophores is, therefore, in high demand to increase structural diversity and variability. Although coumarins and quinolinones have long been acknowledged as organic chromophores, their ability to participate in photoinduced transformations is somewhat less familiar. Fascinated by their chromophoric features and adaptable platform, our group is interested in the identification of fluorescent bioactive molecules and in the development of new photoinduced synthetic methods using coumarins and quinolinones as photocatalysts. This account provides an overview of our recent progress in the discovery and application of light-absorbing coumarin and quinolinone derivatives in photochemistry and medicinal chemistry.
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Affiliation(s)
- Myojeong Kim
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea.,Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Seonghyeok Hong
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea.,Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Jinwook Jeong
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea.,Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Sungwoo Hong
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea.,Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
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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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Kratz T, Steinbach P, Breitenlechner S, Storch G, Bannwarth C, Bach T. Photochemical Deracemization of Chiral Alkenes via Triplet Energy Transfer. J Am Chem Soc 2022; 144:10133-10138. [PMID: 35658423 DOI: 10.1021/jacs.2c02511] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A visible-light-mediated, enantioselective approach to axially chiral alkenes is described. Starting from a racemic mixture, a major alkene enantiomer is formed due to selective triplet energy transfer from a catalytically active chiral sensitizer. A catalyst loading of 2 mol % was sufficient to guarantee consistently high enantioselectivities and yields (16 examples, 51%-quant., 81-96% ee). NMR studies and DFT computations revealed that triplet energy transfer is more rapid within the substrate-catalyst complex of the minor alkene enantiomer. Since this enantiomer is continuously racemized, the major enantiomer is enriched in the photostationary state.
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Affiliation(s)
- Thilo Kratz
- School of Natural Sciences, Department Chemie, and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Pit Steinbach
- Institut für Physikalische Chemie, RWTH Aachen University, 52074 Aachen, Germany
| | - Stefan Breitenlechner
- School of Natural Sciences, Department Chemie, and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Golo Storch
- School of Natural Sciences, Department Chemie, and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Christoph Bannwarth
- Institut für Physikalische Chemie, RWTH Aachen University, 52074 Aachen, Germany
| | - Thorsten Bach
- School of Natural Sciences, Department Chemie, and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany
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12
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Photochemical α-Deracemization of Carbonyl Compounds. Tetrahedron Lett 2022. [DOI: 10.1016/j.tetlet.2022.153808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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13
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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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14
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Zhou J, Wang C, Zhou C, Duo F, Chu L, Zhang M. Self-supporting photocatalyst of 2D Bi 2O 3 anchored on carbon paper for degradation pollutants. RSC Adv 2022; 12:33449-33458. [PMID: 36425167 PMCID: PMC9680007 DOI: 10.1039/d2ra06042f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Accepted: 11/18/2022] [Indexed: 11/23/2022] Open
Abstract
Two-dimensional vertically aligned Bi2O3 nanosheets over carbon paper (CP) were prepared via an in situ growth approach. Bi2O3/CP exhibits a robust photocatalytic activity, as well as renewability and flexibility. With Rhodamine B and 2,4-dichlorophenol used as target pollutants, the rate constant of Bi2O3/CP was 3.72 × 10−3 min−1 and 6.93 × 10−3 min−1 under visible-light irradiation for 2 h, respectively. The improved activity was attributed to the synergistic effects of the hierarchical structure of Bi2O3 and the conductive substrate, CP; the former provided efficient catalytic sites for the pollutants and absorbed more of the light scattered among the nanosheets, while the latter is beneficial to the photogenerated electron transfer. Two-dimensional vertically aligned Bi2O3 nanosheets over carbon paper (CP) were prepared via an in situ growth approach.![]()
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Affiliation(s)
- Jianwei Zhou
- College of Chemistry and Material Engineering, Xinxiang University, Xinxiang 453003, China
- Photoelectrocatalytic Material and Micro-nano Application Technology Academician Workstation, Xinxiang University, Xinxiang 453003, China
| | - Chubei Wang
- Photoelectrocatalytic Material and Micro-nano Application Technology Academician Workstation, Xinxiang University, Xinxiang 453003, China
| | - Chen Zhou
- College of Foreign Languages, Xinxiang University, Xinxiang 453003, China
| | - Fangfang Duo
- Photoelectrocatalytic Material and Micro-nano Application Technology Academician Workstation, Xinxiang University, Xinxiang 453003, China
| | - Liangliang Chu
- Photoelectrocatalytic Material and Micro-nano Application Technology Academician Workstation, Xinxiang University, Xinxiang 453003, China
| | - Mingliang Zhang
- Photoelectrocatalytic Material and Micro-nano Application Technology Academician Workstation, Xinxiang University, Xinxiang 453003, China
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15
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Großkopf J, Plaza M, Seitz A, Breitenlechner S, Storch G, Bach T. Photochemical Deracemization at sp 3-Hybridized Carbon Centers via a Reversible Hydrogen Atom Transfer. J Am Chem Soc 2021; 143:21241-21245. [PMID: 34902253 DOI: 10.1021/jacs.1c11266] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A photochemical deracemization of 5-substituted 3-phenylimidazolidine-2,4-diones (hydantoins) is reported (27 examples, 69%-quant., 80-99% ee). The reaction is catalyzed by a chiral diarylketone which displays a two-point hydrogen bonding site. Mechanistic evidence (DFT calculations, radical clock experiments, H/D labeling) suggests the reaction to occur by selective hydrogen atom transfer (HAT). Upon hydrogen binding, one substrate enantiomer displays the hydrogen atom at the stereogenic center to the photoexcited catalyst allowing for a HAT from the substrate and eventually for its conversion into the product enantiomer. The product enantiomer is not processed by the catalyst and is thus enriched in the photostationary state.
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Affiliation(s)
- Johannes Großkopf
- School of Natural Sciences, Department Chemie, and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Manuel Plaza
- School of Natural Sciences, Department Chemie, and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Antonia Seitz
- School of Natural Sciences, Department Chemie, and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Stefan Breitenlechner
- School of Natural Sciences, Department Chemie, and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Golo Storch
- School of Natural Sciences, Department Chemie, and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Thorsten Bach
- School of Natural Sciences, Department Chemie, and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany
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16
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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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17
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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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18
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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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19
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Huang H, Shi R, Zhang X, Zhao J, Su C, Zhang T. Photothermal‐Assisted Triphase Photocatalysis Over a Multifunctional Bilayer Paper. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202110336] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Affiliation(s)
- Huining Huang
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials Technical Institute of Physics and Chemistry Chinese Academy of Sciences Beijing 100190 China
- International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education Institute of Microscale Optoelectronics Shenzhen University Shenzhen 518060 China
| | - Run Shi
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials Technical Institute of Physics and Chemistry Chinese Academy of Sciences Beijing 100190 China
| | - Xuerui Zhang
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials Technical Institute of Physics and Chemistry Chinese Academy of Sciences Beijing 100190 China
- Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing 100049 China
| | - Jiaqing Zhao
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials Technical Institute of Physics and Chemistry Chinese Academy of Sciences Beijing 100190 China
- Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing 100049 China
| | - Chenliang Su
- International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education Institute of Microscale Optoelectronics Shenzhen University Shenzhen 518060 China
| | - Tierui Zhang
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials Technical Institute of Physics and Chemistry Chinese Academy of Sciences Beijing 100190 China
- Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing 100049 China
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20
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Huang H, Shi R, Zhang X, Zhao J, Su C, Zhang T. Photothermal-assisted triphase photocatalysis over a multifunctional bilayer paper. Angew Chem Int Ed Engl 2021; 60:22963-22969. [PMID: 34374187 DOI: 10.1002/anie.202110336] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Indexed: 12/07/2022]
Abstract
Photocatalysis as one of the future environment technologies has been investigated for decades. Despite great efforts in catalyst engineering, the widely used powder dispersion and photoelectrode systems are still restricted by sluggish interfacial mass transfer and chemical processes. Here we develop a scalable bilayer paper from commercialized TiO 2 and carbon nanomaterials, self-supported at gas-liquid-solid interfaces for photothermal-assisted triphase photocatalysis. The photogeneration of reactive oxygen species can be facilitated through fast oxygen diffusion over triphase interfaces, while the interfacial photothermal effect promotes the following free radical reaction for advanced oxidation of phenol. Under full spectrum irradiation, the triphase system shows 13 times higher reaction rate than diphase controlled system, achieving 88.4% mineralization of high concentration phenol within 90 min full spectrum irradiation. The bilayer paper also exhibits high stability over 40 times cycling experiments and sunlight driven feasibility, showing potentials for large scale photocatalytic applications by being further integrated into a triphase flow reactor.
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Affiliation(s)
- Huining Huang
- Technical Institute of Physics and Chemistry Chinese Academy of Sciences: Technical Institute of Physics and Chemistry, KLPCOM, CHINA
| | - Run Shi
- Technical Institute of Physics and Chemistry Chinese Academy of Sciences: Technical Institute of Physics and Chemistry, KLPCOM, CHINA
| | - Xuerui Zhang
- Technical Institute of Physics and Chemistry Chinese Academy of Sciences: Technical Institute of Physics and Chemistry, KLPCOM, CHINA
| | - Jiaqing Zhao
- Technical Institute of Physics and Chemistry Chinese Academy of Sciences: Technical Institute of Physics and Chemistry, KLPCOM, CHINA
| | - Chenliang Su
- Shenzhen University, Institute of microscale and optoelectronics, CHINA
| | - Tierui Zhang
- Technical Institute of Physics and Chemistry (TIPC), Chinese Academy of Sciences (CAS), Key Laboratory of Photochemical Conversion and Optoelectronic Materials, No.29 Zhongguancun East Road, Haidian District,, 100190, Beijing, CHINA
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21
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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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22
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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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23
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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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24
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Li F, Qiang Z, Chen S, Wei J, Li T, Zhang D. Synthesis of CdS-loaded (CuC 10H 26N 6) 3(PW 12O 40) 2 for enhanced photocatalytic degradation of tetracycline under simulated solar light irradiation. RSC Adv 2020; 10:37072-37079. [PMID: 35521265 PMCID: PMC9057070 DOI: 10.1039/d0ra03755a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Accepted: 09/18/2020] [Indexed: 01/19/2023] Open
Abstract
Largely discharged and excreted medical pollutants pose huge threats to ecosystems. However, typical photocatalysts, such as the Keggin-typed H3PW12O40, can hardly degrade these hazards under visible-light due to their broad bandgap and catalytic disability. In this work, the visible light harvesting was enabled by combining macrocyclic coordination compound CuC10H26N6Cl2O8 with H3PW12O40, and the resulting CuPW was loaded with CdS to reach robust catalytic ability to totally detoxify medicines. We prepared the CuPW–CdS composites through a facile precipitation method, and it showed excellent photocatalytic degradation for degrading tetracycline under visible-light irradiation. The (CuC10H26N6)3(PW12O40)2 with 10 wt% load of CdS shows the highest performance and is ∼6 times more efficient than the pure CuPW counterpart. The heterojunctional CuPW–CdS composites promote the separation of electrons and holes, and consequentially enhance photocatalytic activity. Thanks to migration of electrons from CdS to CuPW, the photocorrosion of CdS is prohibited, resulting in a high chemical stability during photocatalysis. In this work we design a new route to the multi-structural composite photocatalysts for practical applications in medical pollutant decontamination. We demonstrated the incorporation of (CuC12H30N6)2+ into the a Keggin type H3PW12O40 by a simple one-pot self-assembly process. A heterojunction structure was constructed by introducing CdS which has high photocatalytic activities.![]()
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Affiliation(s)
- Feng Li
- College of Chemistry, Key Lab of Environment Friendly Chemistry and Application in Ministry of Education, Xiangtan University Xiangtan 411105 China.,Nano and Molecular Systems Research Unit, Faculty of Science, University of Oulu P.O. Box 3000 FIN-90014 Finland
| | - Zhuomin Qiang
- College of Chemistry, Key Lab of Environment Friendly Chemistry and Application in Ministry of Education, Xiangtan University Xiangtan 411105 China
| | - Shunqiang Chen
- College of Chemistry, Key Lab of Environment Friendly Chemistry and Application in Ministry of Education, Xiangtan University Xiangtan 411105 China
| | - Jianyu Wei
- China Tobacco Guangxi Industrial Co., Ltd Nanning Guangxi 530001 PR China
| | - Taohai Li
- College of Chemistry, Key Lab of Environment Friendly Chemistry and Application in Ministry of Education, Xiangtan University Xiangtan 411105 China.,Nano and Molecular Systems Research Unit, Faculty of Science, University of Oulu P.O. Box 3000 FIN-90014 Finland
| | - Dabin Zhang
- School of Mechanical Engineering, Guizhou University Guiyang Guizhou 550025 PR China
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25
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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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26
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Abstract
Either stereo reactants or stereo catalysis from achiral or chiral molecules are a prerequisite to obtain pure enantiomeric lipid derivatives. We reviewed a few plausibly organic syntheses of phospholipids under prebiotic conditions with special attention paid to the starting materials as pro-chiral dihydroxyacetone and dihydroxyacetone phosphate (DHAP), which are the key molecules to break symmetry in phospholipids. The advantages of homochiral membranes compared to those of heterochiral membranes were analysed in terms of specific recognition, optimal functions of enzymes, membrane fluidity and topological packing. All biological membranes contain enantiomerically pure lipids in modern bacteria, eukarya and archaea. The contemporary archaea, comprising of methanogens, halobacteria and thermoacidophiles, are living under extreme conditions reminiscent of primitive environment and may indicate the origin of one ancient evolution path of lipid biosynthesis. The analysis of the known lipid metabolism reveals that all modern cells including archaea synthetize enantiomerically pure lipid precursors from prochiral DHAP. Sn-glycerol-1-phosphate dehydrogenase (G1PDH), usually found in archaea, catalyses the formation of sn-glycerol-1-phosphate (G1P), while sn-glycerol-3-phosphate dehydrogenase (G3PDH) catalyses the formation of sn-glycerol-3-phosphate (G3P) in bacteria and eukarya. The selective enzymatic activity seems to be the main strategy that evolution retained to obtain enantiomerically pure lipids. The occurrence of two genes encoding for G1PDH and G3PDH served to build up an evolutionary tree being the basis of our hypothesis article focusing on the evolution of these two genes. Gene encoding for G3PDH in eukarya may originate from G3PDH gene found in rare archaea indicating that archaea appeared earlier in the evolutionary tree than eukarya. Archaea and bacteria evolved probably separately, due to their distinct respective genes coding for G1PDH and G3PDH. We propose that prochiral DHAP is an essential molecule since it provides a convergent link between G1DPH and G3PDH. The synthesis of enantiopure phospholipids from DHAP appeared probably firstly in the presence of chemical catalysts, before being catalysed by enzymes which were the products of later Darwinian selection. The enzymes were probably selected for their efficient catalytic activities during evolution from large libraries of vesicles containing amino acids, carbohydrates, nucleic acids, lipids, and meteorite components that induced symmetry imbalance.
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27
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Zhu DL, Wu Q, Young DJ, Wang H, Ren ZG, Li HX. Acyl Radicals from α-Keto Acids Using a Carbonyl Photocatalyst: Photoredox-Catalyzed Synthesis of Ketones. Org Lett 2020; 22:6832-6837. [DOI: 10.1021/acs.orglett.0c02351] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Da-Liang Zhu
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
| | - Qi Wu
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
| | - David James Young
- College of Engineering, Information Technology and Environment, Charles Darwin University, Darwin, Northern Territory 0909, Australia
| | - Hao Wang
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
| | - Zhi-Gang Ren
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
| | - Hong-Xi Li
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
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28
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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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29
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Plaza M, Jandl C, Bach T. Photochemical Deracemization of Allenes and Subsequent Chirality Transfer. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202004797] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Manuel Plaza
- 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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30
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Hong BC. Enantioselective synthesis enabled by visible light photocatalysis. Org Biomol Chem 2020; 18:4298-4353. [PMID: 32458948 DOI: 10.1039/d0ob00759e] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
Enantioselective photoreaction has been a synthetic challenge for decades. With the continuous development of modern visible light photocatalysis and asymmetric catalysis, remarkable advances have been achieved through the synergistic action of these catalytic reactions, allowing the construction of various enantiomerically enriched molecules that were once inaccessible using photocatalytic reactions. This review presents some of the contemporary developments in enantioselective visible-light photocatalysis reactions, covering the period from 2008 to March 2020, with the contents classified by catalysis type.
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Affiliation(s)
- Bor-Cherng Hong
- Department of Chemistry and Biochemistry, National Chung Cheng University, Chia-Yi, 621, Taiwan, Republic of China.
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31
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Zheng L, Xue H, Wong WK, Cao H, Wu J, Khan SA. Cloud-inspired multiple scattering for light intensified photochemical flow reactors. REACT CHEM ENG 2020. [DOI: 10.1039/d0re00080a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
A novel photoflow reactor that mimics how nature accelerates photochemistry in the clouds.
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Affiliation(s)
- Lu Zheng
- Department of Chemical and Biomolecular Engineering
- National University of Singapore
- Singapore 117576
- Singapore
| | - Hansong Xue
- Department of Chemical and Biomolecular Engineering
- National University of Singapore
- Singapore 117576
- Singapore
| | - Wai Kuan Wong
- Department of Chemical and Biomolecular Engineering
- National University of Singapore
- Singapore 117576
- Singapore
| | - Hui Cao
- Department of Chemistry
- National University of Singapore
- Singapore 117543
- Singapore
| | - Jie Wu
- Department of Chemistry
- National University of Singapore
- Singapore 117543
- Singapore
| | - Saif A. Khan
- Department of Chemical and Biomolecular Engineering
- National University of Singapore
- Singapore 117576
- Singapore
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