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Yan P, Stegbauer S, Wu Q, Kolodzeiski E, Stein CJ, Lu P, Bach T. Enantioselective Intramolecular ortho Photocycloaddition Reactions of 2-Acetonaphthones. Angew Chem Int Ed Engl 2024; 63:e202318126. [PMID: 38275271 DOI: 10.1002/anie.202318126] [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: 11/27/2023] [Revised: 01/22/2024] [Accepted: 01/23/2024] [Indexed: 01/27/2024]
Abstract
2-Acetonaphthones, which bear an alkenyl group tethered to its C1 carbon atom via an oxygen atom, were found to undergo an enantioselective intramolecular ortho photocycloaddition reaction. A chiral oxazaborolidine Lewis acid leads to a bathochromic absorption shift of the substrate and enables an efficient enantioface differentiation. Visible light irradiation (λ=450 nm) triggers the reaction which is tolerant of various groups at almost any position except carbon atom C8 (16 examples, 53-99 % yield, 80-97 % ee). Consecutive reactions were explored including a sensitized rearrangement to tetrahydrobiphenylenes, which occurred with full retention of configuration. Evidence was collected that the catalytic photocycloaddition occurs via triplet intermediates, and the binding mode of the acetonaphthone to the chiral Lewis acid was elucidated by DFT calculations.
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Affiliation(s)
- Peng Yan
- Research Center for Molecular Recognition and Synthesis, Department of Chemistry, Fudan University, 220 Handan Lu, Shanghai, 200433, China
| | - Simone Stegbauer
- Department Chemie and Catalysis Research Center (CRC) School of Natural Sciences, Technische Universität München, Lichtenbergstraße 4, D-85747, Garching, Germany
| | - Qinqin Wu
- Research Center for Molecular Recognition and Synthesis, Department of Chemistry, Fudan University, 220 Handan Lu, Shanghai, 200433, China
| | - Elena Kolodzeiski
- Department Chemie and Catalysis Research Center (CRC) School of Natural Sciences, Technische Universität München, Lichtenbergstraße 4, D-85747, Garching, Germany
| | - Christopher J Stein
- Department Chemie and Catalysis Research Center (CRC) School of Natural Sciences, Technische Universität München, Lichtenbergstraße 4, D-85747, Garching, Germany
| | - Ping Lu
- Research Center for Molecular Recognition and Synthesis, Department of Chemistry, Fudan University, 220 Handan Lu, Shanghai, 200433, China
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC) School of Natural Sciences, Technische Universität München, Lichtenbergstraße 4, D-85747, Garching, Germany
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Chen Y, Zhang S, Li Y, Li T, Ma Q, Yuan Y, Jia X. CBr 4 as a Mild Oxidant-Enabled Oxidation of a sp 3 C-H Bond: A Facile Synthesis of the Persistent Iminium Salts of Tetrahydroisoquinolines. Chemistry 2024; 30:e202303952. [PMID: 38193608 DOI: 10.1002/chem.202303952] [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: 11/28/2023] [Revised: 12/26/2023] [Accepted: 01/04/2024] [Indexed: 01/10/2024]
Abstract
Using CBr4 as a mild oxidant, the direct C-H bond oxidation of N-aryltetrahydroisoquinolines was achieved, giving a series of the corresponding iminium salts in high yields under metal- and photo-free reaction conditions. This reaction is superior in high yields and good functional group tolerance, and the late-stage derivatization showed that these iminium salts can readily be applied to the synthesis of the functionalized THIQs.
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Affiliation(s)
- Yuqin Chen
- School of Chemistry and Chemical Engineering, Yangzhou University, Siwangting Road 180, Yangzhou, Jiangsu, China, 225002
| | - Shuwei Zhang
- School of Chemistry and Chemical Engineering, Yangzhou University, Siwangting Road 180, Yangzhou, Jiangsu, China, 225002
| | - Yuemei Li
- School of Chemistry and Chemical Engineering, Yangzhou University, Siwangting Road 180, Yangzhou, Jiangsu, China, 225002
| | - Tong Li
- School of Chemistry and Chemical Engineering, Yangzhou University, Siwangting Road 180, Yangzhou, Jiangsu, China, 225002
| | - Qiyuan Ma
- School of Chemistry and Chemical Engineering, Yangzhou University, Siwangting Road 180, Yangzhou, Jiangsu, China, 225002
| | - Yu Yuan
- School of Chemistry and Chemical Engineering, Yangzhou University, Siwangting Road 180, Yangzhou, Jiangsu, China, 225002
| | - Xiaodong Jia
- School of Chemistry and Chemical Engineering, Yangzhou University, Siwangting Road 180, Yangzhou, Jiangsu, China, 225002
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Dutta S, Erchinger JE, Strieth-Kalthoff F, Kleinmans R, Glorius F. Energy transfer photocatalysis: exciting modes of reactivity. Chem Soc Rev 2024; 53:1068-1089. [PMID: 38168974 DOI: 10.1039/d3cs00190c] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Excited (triplet) states offer a myriad of attractive synthetic pathways, including cycloadditions, selective homolytic bond cleavages and strain-release chemistry, isomerizations, deracemizations, or the fusion with metal catalysis. Recent years have seen enormous advantages in enabling these reactivity modes through visible-light-mediated triplet-triplet energy transfer catalysis (TTEnT). This tutorial review provides an overview of this emerging strategy for synthesizing sought-after organic motifs in a mild, selective, and sustainable manner. Building on the photophysical foundations of energy transfer, this review also discusses catalyst design, as well as the challenges and opportunities of energy transfer catalysis.
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Affiliation(s)
- Subhabrata Dutta
- University of Münster, Organisch-Chemisches Institut, Corrensstraße 36, 48149 Münster, Germany.
| | - Johannes E Erchinger
- University of Münster, Organisch-Chemisches Institut, Corrensstraße 36, 48149 Münster, Germany.
| | - Felix Strieth-Kalthoff
- University of Münster, Organisch-Chemisches Institut, Corrensstraße 36, 48149 Münster, Germany.
| | - Roman Kleinmans
- University of Münster, Organisch-Chemisches Institut, Corrensstraße 36, 48149 Münster, Germany.
| | - Frank Glorius
- University of Münster, Organisch-Chemisches Institut, Corrensstraße 36, 48149 Münster, Germany.
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Palai A, Rai P, Maji B. Rejuvenation of dearomative cycloaddition reactions via visible light energy transfer catalysis. Chem Sci 2023; 14:12004-12025. [PMID: 37969572 PMCID: PMC10631258 DOI: 10.1039/d3sc04421a] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 10/12/2023] [Indexed: 11/17/2023] Open
Abstract
Dearomative cycloaddition is a powerful technique to access sp3-rich three-dimensional structural motifs from simple flat, aromatic feedstock. The building-up of unprecedentedly diverse polycyclic scaffolds with increased saturation and stereochemical information having various applications ranging from pharmaceutical to material sciences, is an essential goal in organic chemistry. However, the requirement of large energy inputs to disrupt the aromaticity of an arene moiety necessitates harsh reaction conditions for ground state dearomative cycloaddition. The photochemical requirement encompasses use of ultraviolet (UV) light to enable the reaction on an excited potential energy surface. The microscopic reversibility under thermal conditions and the use of high energy harmful UV irradiation in photochemical manoeuvres, however, constrain their widespread use from a synthetic point of view. In this context, the recent renaissance of visible light energy transfer (EnT) catalysis has become a powerful tool to initiate dearomative cycloaddition as a greener and more sustainable approach. The excited triplet state population is achieved by triplet energy transfer from the appropriate photosensitizer to the substrate. While employing mild visible light energy as fuel, the process leverages an enormous potential of excited state reactivity. The discovery of an impressive portfolio of organic and inorganic photosensitizers with a range of triplet energies facilitates visible light photosensitized dearomative cycloaddition of various substrates to form sp3-rich fused polycyclic architectures with diverse applications. The tutorial review comprehensively surveys the reawakening of dearomative cycloadditions via visible light-mediated energy transfer catalysis in the past five years. The progress ranges from intra- and intermolecular [2π + 2π] to [4π + 2π], and ends at intermolecular [2π + 2σ] cycloadditions. Furthermore, the review provides potential possibilities for future growth in the growing field of visible light energy transfer catalysis.
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Affiliation(s)
- Angshuman Palai
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata Mohanpur 741246 West Bengal India
| | - Pramod Rai
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata Mohanpur 741246 West Bengal India
| | - Biplab Maji
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata Mohanpur 741246 West Bengal India
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Stegbauer S, Jandl C, Bach T. Chiral Lewis acid catalysis in a visible light-triggered cycloaddition/rearrangement cascade. Chem Sci 2022; 13:11856-11862. [PMID: 36320923 PMCID: PMC9580482 DOI: 10.1039/d2sc03159k] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Accepted: 09/18/2022] [Indexed: 07/10/2024] Open
Abstract
Cascade (domino) reactions facilitate the formation of complex molecules from simple starting materials in a single operation. It was found that 1-naphthaldehyde derivatives can be converted to enantioenriched (82-96% ee) polycyclic benzoisochromenes via a cascade of ortho photocycloaddition and ensuing acid-catalysed rearrangement reactions. The cascade was initiated by irradiation with visible light (λ = 457 nm) and catalysed by a chiral AlBr3-activated 1,3,2-oxazaborolidine (14 examples, 65-93% yield). The absolute configuration of the products was elucidated by single crystal X-ray crystallography. Mechanistic experiments suggest that the ortho photocycloaddition occurs on the triplet hypersurface and that the chiral catalyst induces in this step the observed enantioselectivity.
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Affiliation(s)
- Simone Stegbauer
- Technische Universität München, School of Natural Sciences, Department of Chemistry and Catalysis Research Center Lichtenbergstrasse 4 Garching 85747 Germany https://www.ch.nat.tum.de/en/oc1/home/ +49 (0)89 289 13315
| | - Christian Jandl
- Technische Universität München, School of Natural Sciences, Department of Chemistry and Catalysis Research Center Lichtenbergstrasse 4 Garching 85747 Germany https://www.ch.nat.tum.de/en/oc1/home/ +49 (0)89 289 13315
| | - Thorsten Bach
- Technische Universität München, School of Natural Sciences, Department of Chemistry and Catalysis Research Center Lichtenbergstrasse 4 Garching 85747 Germany https://www.ch.nat.tum.de/en/oc1/home/ +49 (0)89 289 13315
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