1
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Luz Tibaldi-Bollati M, Nicotra V, Oksdath-Mansilla G, García ME. Expanding Diterpene Complexity and Diversity via Photoinduced Ring Distortions. Chempluschem 2024; 89:e202300537. [PMID: 38029375 DOI: 10.1002/cplu.202300537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Revised: 11/23/2023] [Accepted: 11/29/2023] [Indexed: 12/01/2023]
Abstract
Natural products and their semi-synthetic derivatives undoubtedly constitute an important source of therapeutic agents. Their importance lies in their own origin and evolution, since they have great chemical diversity, biochemical specificity, and pharmacological properties. Currently, there is a renewed interest in the development of methodologies capable of efficiently modifying the chemical structure of these bioactive platforms. In this work, the photoderivatization of the diterpene solidagenone was performed using a complexity-to-diversity-oriented approach. By exploring [2+2]-photocycloaddition, photoinduced-hydrogen abstraction, and photoxygenation reactions, a set of solidagenone derivatives was obtained, showing different ring fusions, side chain rearrangements, and modifications of the original furan ring's substitution pattern. The derivatives obtained were characterised by NMR methodologies. To evaluate the structural diversity of the labdane-derived compounds, their physicochemical properties, structural similarity, and chemical space were analysed. These results suggest that photochemical reactions are a useful tool for performing ring distortion transformations, generating derivatives of natural compounds with wide diversity, structural complexity, and with potential biological properties.
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Affiliation(s)
- María Luz Tibaldi-Bollati
- Dpto. de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA, Córdoba, Argentina
- Instituto Multidisciplinario de Biología Vegetal (IMBIV), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Córdoba, Argentina
| | - Viviana Nicotra
- Dpto. de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA, Córdoba, Argentina
- Instituto Multidisciplinario de Biología Vegetal (IMBIV), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Córdoba, Argentina
| | - Gabriela Oksdath-Mansilla
- Dpto. de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA, Córdoba, Argentina
- Instituto de Investigaciones en Físico-Química de Córdoba (INFIQC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Córdoba, Argentina
| | - Manuela E García
- Dpto. de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA, Córdoba, Argentina
- Instituto Multidisciplinario de Biología Vegetal (IMBIV), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Córdoba, Argentina
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2
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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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3
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Yan P, Zhang J, Lu L, Fang H, Lu P. Enantioselective Construction of Vicinal Angular Quaternary Stereocenters Enabled by Strained Cyclobutenones. ACS Catal 2022. [DOI: 10.1021/acscatal.2c05265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Affiliation(s)
- Peng Yan
- Research Center for Molecular Recognition and Synthesis, Department of Chemistry, Fudan University, 220 Handan Lu, Shanghai, 200433, People’s Republic of China
| | - Jia Zhang
- School of Materials Science and Engineering, Tianjin Key Lab for Rare Earth Materials and Applications, Nankai University, Tianjin, 300350, People’s Republic of China
| | - Licheng Lu
- Research Center for Molecular Recognition and Synthesis, Department of Chemistry, Fudan University, 220 Handan Lu, Shanghai, 200433, People’s Republic of China
| | - Huayi Fang
- School of Materials Science and Engineering, Tianjin Key Lab for Rare Earth Materials and Applications, Nankai University, Tianjin, 300350, People’s Republic of China
| | - Ping Lu
- Research Center for Molecular Recognition and Synthesis, Department of Chemistry, Fudan University, 220 Handan Lu, Shanghai, 200433, People’s Republic of China
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4
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Proessdorf J, Jandl C, Pickl T, Bach T. Arene Activation through Iminium Ions: Product Diversity from Intramolecular Photocycloaddition Reactions. Angew Chem Int Ed Engl 2022; 61:e202208329. [PMID: 35920713 PMCID: PMC9826208 DOI: 10.1002/anie.202208329] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Indexed: 01/11/2023]
Abstract
While 2-alk-ω-enyloxy-sustituted benzaldehydes do not display any photochemical reactivity at the arene core, the respective iminium perchlorates were found to undergo efficient reactions either upon direct irradiation (λ=366 nm) or under sensitizing conditions (λ=420 nm, 2.5 mol% thioxanthen-9-one). Three pathways were found: (a) Most commonly, the reaction led to benzoxacyclic products in which the olefin in the tether underwent a formal, yet unprecedented carboformylation (13 examples, 44-99 % yield). The cascade process occurred with high diastereoselectivity and was found to be stereoconvergent. (b) If a substituent resides in the 3-position of the benzene ring, a meta photocycloaddition was observed which produced tetracyclic skeletons with five stereogenic centers in excellent regio- and diastereoselectivity (2 examples, 58-79 % yield). (c) If the tether was internally substituted at the alkene, an arene photocycloaddition was avoided and an azetidine was formed in an aza Paternò-Büchi reaction (2 examples, 95-98 % yield).
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Affiliation(s)
- Johanna Proessdorf
- Department Chemie and Catalysis Research Center (CRC)School of Natural SciencesTechnische Universität MünchenLichtenbergstraße 485747GarchingGermany
| | - Christian Jandl
- Department Chemie and Catalysis Research Center (CRC)School of Natural SciencesTechnische Universität MünchenLichtenbergstraße 485747GarchingGermany
| | - Thomas Pickl
- Department Chemie and Catalysis Research Center (CRC)School of Natural SciencesTechnische Universität MünchenLichtenbergstraße 485747GarchingGermany
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC)School of Natural SciencesTechnische Universität MünchenLichtenbergstraße 485747GarchingGermany
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5
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Proessdorf J, Jandl C, Pickl T, Bach T. Arene Activation through Iminium Ions: Product Diversity from Intramolecular Photocycloaddition Reactions. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202208329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Johanna Proessdorf
- Technische Universität München: Technische Universitat Munchen Department Chemie GERMANY
| | - Christian Jandl
- Technische Universität München: Technische Universitat Munchen Department Chemie GERMANY
| | - Thomas Pickl
- Technische Universität München: Technische Universitat Munchen Department Chemie GERMANY
| | - Thorsten Bach
- Technische Universität München Lehrstuhl für Organische Chemie I Lichtenbergstr. 4 85747 Garching GERMANY
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6
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Shimizu N, Shigemitsu H, Kida T, Bach T, Mori T. Visible Light-Induced Regio- and Enantiodifferentiating [2 + 2] Photocycloaddition of 1,4-Naphthoquinones Mediated by Oppositely Coordinating 1,3,2-Oxazaborolidine Chiral Lewis Acid. J Org Chem 2022; 87:8071-8083. [PMID: 35652135 DOI: 10.1021/acs.joc.2c00730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A range of asymmetric photochemical transformations using visible light have recently become considerably attractive. Among the various approaches, chiral Lewis acid association to enones for [2 + 2] and ortho photocycloadditions and oxadi-π-methane rearrangements have shown to be very promising. Naturally, chiral Lewis acid coordination protects one of the prochiral faces of the C═C double bond, which enables an effective enantiodifferentiation in the following bond-forming process(es). Here, we studied regio- and enantiodifferentiating [2 + 2] photocycloaddition reactions of naphthoquinone derivatives mediated by chiral oxazaborolidines. A stereochemical control was quite challenging for the 2-ene-1,4-dione substrate, as a double coordination of Lewis acid essentially cancels out the face selectivity, and a mono-coordination to each carbonyl group leads to an opposite stereochemical outcome. Furthermore, a stepwise coordination in the ground state of Lewis acid in a 1:1 fashion was practically inaccessible. We found that the excited-state decomplexation is a key to accomplish high regio- and enantioselectivities in the photocycloaddition of an ene-dione.
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Affiliation(s)
- Nao Shimizu
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Hajime Shigemitsu
- Integrated Frontier Research for Medical Science Division Institute for OTRI, Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Toshiyuki Kida
- Integrated Frontier Research for Medical Science Division Institute for OTRI, Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstrasse 4, Garching 85747, Germany
| | - Tadashi Mori
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
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7
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Triandafillidi I, Nikitas NF, Gkizis PL, Spiliopoulou N, Kokotos CG. Hexafluoroisopropanol-Promoted or Brønsted Acid-Mediated Photochemical [2+2] Cycloadditions of Alkynes with Maleimides. CHEMSUSCHEM 2022; 15:e202102441. [PMID: 34978379 DOI: 10.1002/cssc.202102441] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/23/2021] [Indexed: 06/14/2023]
Abstract
Although the use of light stimulating organic transformations has been known for more than a century, there is an increasing research interest on expanding the established knowledge. While [2+2] cycloadditions are promoted photochemically, literature precedent on the reaction between alkynes and maleimides is limited and only a handful of examples exist, focusing mainly on N-aliphatic maleimides. Herein, the differences in reactivity between N-alkyl and N-aryl maleimides were identified, and the use of hexafluoroisopropanol (HFIP) or trifluoroacetic acid (TFA) as viable solutions was proposed in order to achieve high yields. In the case of N-alkyl maleimides, both HFIP-mediated or TFA-promoted reactions were established using LED 370 nm irradiation, without the use of an external photocatalyst. In the case of N-aryl maleimides, thioxanthone (THX) was employed as the energy transfer photocatalyst along with LED 427 nm irradiation and HFIP. Mechanistic studies were performed, supporting the pivotal role of HFIP or TFA, in acquiring good to high yields in both classes of maleimides.
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Affiliation(s)
- Ierasia Triandafillidi
- Laboratory of Organic Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, 15771, Athens, Greece
| | - Nikolaos F Nikitas
- Laboratory of Organic Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, 15771, Athens, Greece
| | - Petros L Gkizis
- Laboratory of Organic Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, 15771, Athens, Greece
| | - Nikoleta Spiliopoulou
- Laboratory of Organic Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, 15771, Athens, Greece
| | - Christoforos G Kokotos
- Laboratory of Organic Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, 15771, Athens, Greece
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8
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He R, Bai Y, Han G, Zhao Z, Pang X, Pan X, Liu X, Shu X. Reductive Alkylation of Alkenyl Acetates with Alkyl Bromides by Nickel Catalysis. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202114556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Rong‐De He
- State Key Laboratory of Applied Organic Chemistry (SKLAOC) College of Chemistry and Chemical Engineering Lanzhou University 222 South Tianshui Road Lanzhou 730000 China
| | - Yunfei Bai
- State Key Laboratory of Applied Organic Chemistry (SKLAOC) College of Chemistry and Chemical Engineering Lanzhou University 222 South Tianshui Road Lanzhou 730000 China
| | - Guan‐Yu Han
- State Key Laboratory of Applied Organic Chemistry (SKLAOC) College of Chemistry and Chemical Engineering Lanzhou University 222 South Tianshui Road Lanzhou 730000 China
| | - Zhen‐Zhen Zhao
- State Key Laboratory of Applied Organic Chemistry (SKLAOC) College of Chemistry and Chemical Engineering Lanzhou University 222 South Tianshui Road Lanzhou 730000 China
| | - Xiaobo Pang
- State Key Laboratory of Applied Organic Chemistry (SKLAOC) College of Chemistry and Chemical Engineering Lanzhou University 222 South Tianshui Road Lanzhou 730000 China
| | - Xiaobo Pan
- State Key Laboratory of Applied Organic Chemistry (SKLAOC) College of Chemistry and Chemical Engineering Lanzhou University 222 South Tianshui Road Lanzhou 730000 China
| | - Xue‐Yuan Liu
- State Key Laboratory of Applied Organic Chemistry (SKLAOC) College of Chemistry and Chemical Engineering Lanzhou University 222 South Tianshui Road Lanzhou 730000 China
| | - Xing‐Zhong Shu
- State Key Laboratory of Applied Organic Chemistry (SKLAOC) College of Chemistry and Chemical Engineering Lanzhou University 222 South Tianshui Road Lanzhou 730000 China
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9
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Xu B, Shi X, Liu X, Cao H. Construction of Chiral Cyclic Compounds Enabled by Enantioselective Photocatalysis. Molecules 2022; 27:359. [PMID: 35056674 PMCID: PMC8778761 DOI: 10.3390/molecules27020359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Revised: 12/28/2021] [Accepted: 01/03/2022] [Indexed: 12/02/2022] Open
Abstract
Chiral cyclic molecules are some of the most important compounds in nature, and are widely used in the fields of drugs, materials, synthesis, etc. Enantioselective photocatalysis has become a powerful tool for organic synthesis of chiral cyclic molecules. Herein, this review summarized the research progress in the synthesis of chiral cyclic compounds by photocatalytic cycloaddition reaction in the past 5 years, and expounded the reaction conditions, characters, and corresponding proposed mechanism, hoping to guide and promote the development of this field.
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Affiliation(s)
| | | | - Xiang Liu
- Guangdong Cosmetics Engineering & Technology Research Center, School of Chemistry and Chemical Engineering, Guangdong Pharmaceutical University, Zhongshan 528458, China; (B.X.); (X.S.)
| | - Hua Cao
- Guangdong Cosmetics Engineering & Technology Research Center, School of Chemistry and Chemical Engineering, Guangdong Pharmaceutical University, Zhongshan 528458, China; (B.X.); (X.S.)
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10
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Rigotti T, Schwinger DP, Graßl R, Jandl C, Bach T. Enantioselective crossed intramolecular [2+2] photocycloaddition reactions mediated by a chiral chelating Lewis acid. Chem Sci 2022; 13:2378-2384. [PMID: 35310494 PMCID: PMC8864722 DOI: 10.1039/d2sc00113f] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 02/01/2022] [Indexed: 12/01/2022] Open
Abstract
In intramolecular [2+2] photocycloaddition reactions, the two tethered olefins can approach each other in a straight or in a crossed fashion. Despite the fact that the latter reaction mode leads to intriguing, otherwise inaccessible bridged skeletons, there has so far not been any enantioselective variants thereof. This study concerned the crossed [2+2]-photocycloaddition of 2-(alkenyloxy)cyclohex-2-enones to bridged cyclobutanes. It was found that the reaction could be performed with high enantioselectivity (80–94% ee) under visible light conditions when employing a chiral rhodium Lewis acid as a catalyst (2 mol%). An enantioselective crossed [2+2] photocycloaddition is presented which proceeds under visible light irradiation in the presence of a chiral Lewis acidic metal complex. Chelation of two oxygen atoms to the metal centre accounts for the observed enantioface differentiation.![]()
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Affiliation(s)
- Thomas Rigotti
- School of Natural Sciences, Department Chemie, Catalysis Research Center (CRC), Technische Universität München 85747 Garching Germany +49 89 28913315 +49 89 28913330
| | - Daniel P Schwinger
- School of Natural Sciences, Department Chemie, Catalysis Research Center (CRC), Technische Universität München 85747 Garching Germany +49 89 28913315 +49 89 28913330
| | - Raphaela Graßl
- School of Natural Sciences, Department Chemie, Catalysis Research Center (CRC), Technische Universität München 85747 Garching Germany +49 89 28913315 +49 89 28913330
| | - Christian Jandl
- School of Natural Sciences, Department Chemie, Catalysis Research Center (CRC), Technische Universität München 85747 Garching Germany +49 89 28913315 +49 89 28913330
| | - Thorsten Bach
- School of Natural Sciences, Department Chemie, Catalysis Research Center (CRC), Technische Universität München 85747 Garching Germany +49 89 28913315 +49 89 28913330
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11
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Mukhopadhyay S, Boobalan R, Chein RJ. Oxathiaborolium-catalyzed enantioselective [2 + 2] cycloadditions. Org Biomol Chem 2022; 20:8405-8409. [DOI: 10.1039/d2ob01779b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The one-pot-prepared oxathiaborolium pentachlorostannate is an excellent Lewis acid and is successfully used to catalyze the [2 + 2] cycloadditions of N-substituted maleimides and silyl enol ethers with excellent enantioselectivities.
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Affiliation(s)
| | | | - Rong-Jie Chein
- Institute of Chemistry, Academia Sinica, Nankang, Taipei 11529, Taiwan
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12
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Zhao Y, Huo M, Zhou H. DFT study on the gold(I)-catalyzed cycloaddition and rearrangement reactions of allene-containing allylic silyl ether. J Mol Model 2021; 28:25. [PMID: 34970719 DOI: 10.1007/s00894-021-05004-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Accepted: 12/14/2021] [Indexed: 01/14/2023]
Abstract
The DFT calculation at the B3LYP/B3LYP-D3(BJ) level was carried out to explore the reaction mechanism of the synthesis of spirocyclo[4,5]decane skeleton by gold-catalyzed allenyl compounds. The more accurate energy under the CH3CN solvent in the experiment is calculated by the single-point energy of the SMD model. Computational studies have shown that the reaction consists of three main steps: intramolecular cycloaddition of the end group carbon atoms of allenyl and vinyl groups, the semipinacol rearrangement process in which the four-membered ring is reconstructed into the five-membered ring, the elimination reaction releases the catalyst and obtains the product. The calculation results show that Zheng et al. reported that the gold-catalyzed synthesis reaction can easily occur under the experimental conditions due to its low activation free energy (12.07-15.49 kcal/mol). Furthermore, it was found that the MOMO(CH2)2 substituent has higher reactivity than the corresponding reactant of the phenyl substituent.
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Affiliation(s)
- YaMei Zhao
- School of Environmental and Chemical Engineering, Xi'an Polytechnic University, Xi'an, 710048, Shaanxi, China.
| | - MengDan Huo
- School of Environmental and Chemical Engineering, Xi'an Polytechnic University, Xi'an, 710048, Shaanxi, China
| | - HongJi Zhou
- School of Environmental and Chemical Engineering, Xi'an Polytechnic University, Xi'an, 710048, Shaanxi, China
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13
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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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14
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He RD, Bai Y, Han GY, Zhao ZZ, Pang X, Pan X, Liu XY, Shu XZ. Reductive Alkylation of Alkenyl Acetates with Alkyl Bromides by Nickel Catalysis. Angew Chem Int Ed Engl 2021; 61:e202114556. [PMID: 34862693 DOI: 10.1002/anie.202114556] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Indexed: 01/07/2023]
Abstract
Catalytic alkylation of stable alkenyl C-O electrophiles is synthetically appealing, but studies to date have typically focused on the reactions with alkyl Grignard reagents. We report herein a cross-electrophile reaction of alkenyl acetates with alkyl bromides. This work has enabled a new method for the synthesis of aliphatic alkenes from alkenyl acetates to be established that can be used to add more structural complexity and molecular diversity with enhanced functionality tolerance. The method allows for a gram-scale reaction and modification of biologically active molecules, and it affords access to useful building blocks. Preliminary mechanistic studies reveal that the NiI species plays an essential role for the success of the coupling of these two reactivity-mismatched electrophiles.
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Affiliation(s)
- Rong-De He
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), College of Chemistry and Chemical Engineering, Lanzhou University, 222 South Tianshui Road, Lanzhou, 730000, China
| | - Yunfei Bai
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), College of Chemistry and Chemical Engineering, Lanzhou University, 222 South Tianshui Road, Lanzhou, 730000, China
| | - Guan-Yu Han
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), College of Chemistry and Chemical Engineering, Lanzhou University, 222 South Tianshui Road, Lanzhou, 730000, China
| | - Zhen-Zhen Zhao
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), College of Chemistry and Chemical Engineering, Lanzhou University, 222 South Tianshui Road, Lanzhou, 730000, China
| | - Xiaobo Pang
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), College of Chemistry and Chemical Engineering, Lanzhou University, 222 South Tianshui Road, Lanzhou, 730000, China
| | - Xiaobo Pan
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), College of Chemistry and Chemical Engineering, Lanzhou University, 222 South Tianshui Road, Lanzhou, 730000, China
| | - Xue-Yuan Liu
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), College of Chemistry and Chemical Engineering, Lanzhou University, 222 South Tianshui Road, Lanzhou, 730000, China
| | - Xing-Zhong Shu
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), College of Chemistry and Chemical Engineering, Lanzhou University, 222 South Tianshui Road, Lanzhou, 730000, China
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15
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Mashiko T, Shingai Y, Sakai J, Kamo S, Adachi S, Matsuzawa A, Sugita K. Total Synthesis of Cochlearol B via Intramolecular [2+2] Photocycloaddition. Angew Chem Int Ed Engl 2021; 60:24484-24487. [PMID: 34533883 DOI: 10.1002/anie.202110556] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/15/2021] [Indexed: 11/12/2022]
Abstract
Herein, we describe the first total synthesis of cochlearol B, a meroterpenoid natural product featuring a 4/5/6/6/6-fused pentacyclic structure. Key steps, oxidative cyclization and subsequent intramolecular [2+2] photocycloaddition, which constructed the pentacyclic structure in highly stereoselective manner, allowed efficient access to cochlearol B with the longest linear sequence of 16 steps, and in 9 % overall yield. Single-crystal X-ray crystallographic analysis clearly confirmed the stereochemistry of cochlearol B.
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Affiliation(s)
- Tomoya Mashiko
- Department of Synthetic Medicinal Chemistry, Faculty of Pharmaceutical Sciences, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 142-8501, Japan
| | - Yuta Shingai
- Department of Synthetic Medicinal Chemistry, Faculty of Pharmaceutical Sciences, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 142-8501, Japan
| | - Jun Sakai
- Department of Synthetic Medicinal Chemistry, Faculty of Pharmaceutical Sciences, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 142-8501, Japan
| | - Shogo Kamo
- Department of Synthetic Medicinal Chemistry, Faculty of Pharmaceutical Sciences, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 142-8501, Japan
| | - Shinya Adachi
- Department of Synthetic Medicinal Chemistry, Faculty of Pharmaceutical Sciences, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 142-8501, Japan
| | - Akinobu Matsuzawa
- Department of Synthetic Medicinal Chemistry, Faculty of Pharmaceutical Sciences, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 142-8501, Japan
| | - Kazuyuki Sugita
- Department of Synthetic Medicinal Chemistry, Faculty of Pharmaceutical Sciences, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 142-8501, Japan
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16
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Mashiko T, Shingai Y, Sakai J, Kamo S, Adachi S, Matsuzawa A, Sugita K. Total Synthesis of Cochlearol B via Intramolecular [2+2] Photocycloaddition. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202110556] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Tomoya Mashiko
- Department of Synthetic Medicinal Chemistry Faculty of Pharmaceutical Sciences Hoshi University 2-4-41 Ebara, Shinagawa-ku Tokyo 142-8501 Japan
| | - Yuta Shingai
- Department of Synthetic Medicinal Chemistry Faculty of Pharmaceutical Sciences Hoshi University 2-4-41 Ebara, Shinagawa-ku Tokyo 142-8501 Japan
| | - Jun Sakai
- Department of Synthetic Medicinal Chemistry Faculty of Pharmaceutical Sciences Hoshi University 2-4-41 Ebara, Shinagawa-ku Tokyo 142-8501 Japan
| | - Shogo Kamo
- Department of Synthetic Medicinal Chemistry Faculty of Pharmaceutical Sciences Hoshi University 2-4-41 Ebara, Shinagawa-ku Tokyo 142-8501 Japan
| | - Shinya Adachi
- Department of Synthetic Medicinal Chemistry Faculty of Pharmaceutical Sciences Hoshi University 2-4-41 Ebara, Shinagawa-ku Tokyo 142-8501 Japan
| | - Akinobu Matsuzawa
- Department of Synthetic Medicinal Chemistry Faculty of Pharmaceutical Sciences Hoshi University 2-4-41 Ebara, Shinagawa-ku Tokyo 142-8501 Japan
| | - Kazuyuki Sugita
- Department of Synthetic Medicinal Chemistry Faculty of Pharmaceutical Sciences Hoshi University 2-4-41 Ebara, Shinagawa-ku Tokyo 142-8501 Japan
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17
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Sierra S, Dalmau D, Higuera S, Cortés D, Crespo O, Jimenez AI, Pop A, Silvestru C, Urriolabeitia EP. Reactivity of ( Z)-4-Aryliden-5(4 H)-thiazolones: [2 + 2]-Photocycloaddition, Ring-Opening Reactions, and Influence of the Lewis Acid BF 3. J Org Chem 2021; 86:12119-12140. [PMID: 34479406 PMCID: PMC9129068 DOI: 10.1021/acs.joc.1c01458] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
The
irradiation of (Z)-2-phenyl-4-aryliden-5(4H)-thiazolones 2 with blue light (465 nm) in
CH2Cl2 solution promotes [2 + 2]-photocycloaddition
of the exocyclic C=C bonds and the formation of the dispirocyclobutanes 3. This reaction takes place with high stereoselectivity,
given that the ε-isomer (1,3 head-to-tail syn coupling) is formed
in more than 90% yield in most of the cases. However, irradiation
of 5(4H)-thiazolones 2 with blue light
(456 nm) in dry MeOH in the presence of BF3·OEt2 leads to the monospirocyclobutanes 4 with full
stereoselectivity, also affording the ε-isomer. A ring-opening
reaction of only one of the thiazolone rings appears to have taken
place in 4 upon methanolysis, leading to the corresponding
ester and thioamide groups. The treatment of free 4-aryliden-5(4H)-thiazolones 2 with a base in alcohol (NaOR/ROH)
also produces a ring-opening reaction of the heterocycle by methanolysis,
although, under these reaction conditions, further intramolecular
S-attack at the exocyclic C(H)=C bond and cyclization is observed,
forming the dihydrothiazoles 5 or 6 as mixtures
of cis (RS/SR)-
and trans (RR/SS)-isomers with high diastereomeric excess. trans-(RR/SS)-Dihydrothiazoles 6 can be
isolated as pure diastereoisomers by column chromatography. Surprisingly,
dihydrothiazoles 5 can also be obtained by the treatment
of 4-aryliden-5(4H)-thiazolones 2 with
BF3·OEt2 in methanol in the absence of
a base.
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Affiliation(s)
- Sonia Sierra
- Instituto de Síntesis Química y Catálisis Homogénea, ISQCH (CSIC-Universidad de Zaragoza), Pedro Cerbuna 12, 50009 Zaragoza, Spain
| | - David Dalmau
- Instituto de Síntesis Química y Catálisis Homogénea, ISQCH (CSIC-Universidad de Zaragoza), Pedro Cerbuna 12, 50009 Zaragoza, Spain
| | - Sheila Higuera
- Instituto de Síntesis Química y Catálisis Homogénea, ISQCH (CSIC-Universidad de Zaragoza), Pedro Cerbuna 12, 50009 Zaragoza, Spain
| | - Darío Cortés
- Instituto de Síntesis Química y Catálisis Homogénea, ISQCH (CSIC-Universidad de Zaragoza), Pedro Cerbuna 12, 50009 Zaragoza, Spain
| | - Olga Crespo
- Instituto de Síntesis Química y Catálisis Homogénea, ISQCH (CSIC-Universidad de Zaragoza), Pedro Cerbuna 12, 50009 Zaragoza, Spain
| | - Ana I Jimenez
- Instituto de Síntesis Química y Catálisis Homogénea, ISQCH (CSIC-Universidad de Zaragoza), Pedro Cerbuna 12, 50009 Zaragoza, Spain
| | - Alexandra Pop
- Supramolecular Organic and Organometallic Chemistry Centre, Department of Chemistry, Faculty of Chemistry and Chemical Engineering, Babeş-Bolyai University, Str. Arany Janos 11, 400028 Cluj-Napoca, Romania
| | - Cristian Silvestru
- Supramolecular Organic and Organometallic Chemistry Centre, Department of Chemistry, Faculty of Chemistry and Chemical Engineering, Babeş-Bolyai University, Str. Arany Janos 11, 400028 Cluj-Napoca, Romania
| | - Esteban P Urriolabeitia
- Instituto de Síntesis Química y Catálisis Homogénea, ISQCH (CSIC-Universidad de Zaragoza), Pedro Cerbuna 12, 50009 Zaragoza, Spain
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18
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Peschel MT, Kabaciński P, Schwinger DP, Thyrhaug E, Cerullo G, Bach T, Hauer J, Vivie‐Riedle R. Activation of 2‐Cyclohexenone by BF
3
Coordination: Mechanistic Insights from Theory and Experiment. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202016653] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Martin T. Peschel
- Department Chemie Ludwig-Maximilians-Universität München 81377 München Germany
| | - Piotr Kabaciński
- IFN-CNR and Dipartimento di Fisica Politecnico di Milano 20133 Milano Italy
| | - Daniel P. Schwinger
- Department of Chemistry and Catalysis Research Center (CRC) Technische Universität München 85747 Garching Germany
| | - Erling Thyrhaug
- Department of Chemistry and Catalysis Research Center (CRC) Technische Universität München 85747 Garching Germany
| | - Giulio Cerullo
- IFN-CNR and Dipartimento di Fisica Politecnico di Milano 20133 Milano Italy
| | - Thorsten Bach
- Department of Chemistry and Catalysis Research Center (CRC) Technische Universität München 85747 Garching Germany
| | - Jürgen Hauer
- Department of Chemistry and Catalysis Research Center (CRC) Technische Universität München 85747 Garching Germany
| | - Regina Vivie‐Riedle
- Department Chemie Ludwig-Maximilians-Universität München 81377 München Germany
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19
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Peschel MT, Kabaciński P, Schwinger DP, Thyrhaug E, Cerullo G, Bach T, Hauer J, de Vivie-Riedle R. Activation of 2-Cyclohexenone by BF 3 Coordination: Mechanistic Insights from Theory and Experiment. Angew Chem Int Ed Engl 2021; 60:10155-10163. [PMID: 33595902 PMCID: PMC8252487 DOI: 10.1002/anie.202016653] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 02/01/2021] [Indexed: 11/22/2022]
Abstract
Lewis acids have recently been recognized as catalysts enabling enantioselective photochemical transformations. Mechanistic studies on these systems are however rare, either due to their absorption at wavelengths shorter than 260 nm, or due to the limitations of theoretical dynamic studies for larger complexes. In this work, we overcome these challenges and employ sub-30-fs transient absorption in the UV, in combination with a highly accurate theoretical treatment on the XMS-CASPT2 level. We investigate 2-cyclohexenone and its complex to boron trifluoride and analyze the observed dynamics based on trajectory calculations including non-adiabatic coupling and intersystem crossing. This approach explains all ultrafast decay pathways observed in the complex. We show that the Lewis acid remains attached to the substrate in the triplet state, which in turn explains why chiral boron-based Lewis acids induce a high enantioselectivity in photocycloaddition reactions.
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Affiliation(s)
- Martin T Peschel
- Department Chemie, Ludwig-Maximilians-Universität München, 81377, München, Germany
| | - Piotr Kabaciński
- IFN-CNR and Dipartimento di Fisica, Politecnico di Milano, 20133, Milano, Italy
| | - Daniel P Schwinger
- Department of Chemistry and Catalysis Research Center (CRC), Technische Universität München, 85747, Garching, Germany
| | - Erling Thyrhaug
- Department of Chemistry and Catalysis Research Center (CRC), Technische Universität München, 85747, Garching, Germany
| | - Giulio Cerullo
- IFN-CNR and Dipartimento di Fisica, Politecnico di Milano, 20133, Milano, Italy
| | - Thorsten Bach
- Department of Chemistry and Catalysis Research Center (CRC), Technische Universität München, 85747, Garching, Germany
| | - Jürgen Hauer
- Department of Chemistry and Catalysis Research Center (CRC), Technische Universität München, 85747, Garching, Germany
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20
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Li L, Turnbull WL, McDonald R, West FG. Lithium Hydroxide Assisted
Endo
‐Selective [4+4]‐Photocycloaddition of Pyran‐2‐ones. European J Org Chem 2021. [DOI: 10.1002/ejoc.202100122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Lei Li
- Department of Chemistry University of Alberta E3-43 Gunning-Lemieux Chemistry Centre Edmonton AB T6G 2G2 Canada
| | - William L. Turnbull
- Department of Chemistry University of Alberta E3-43 Gunning-Lemieux Chemistry Centre Edmonton AB T6G 2G2 Canada
| | - Robert McDonald
- X-Ray Crystallography Laboratory Department of Chemistry University of Alberta E3-43 Gunning-Lemieux Chemistry Centre Edmonton AB T6G 2G2 Canada
| | - F. G. West
- Department of Chemistry University of Alberta E3-43 Gunning-Lemieux Chemistry Centre Edmonton AB T6G 2G2 Canada
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21
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de Souza WC, Matsuo BT, Matos PM, Correia JTM, Santos MS, König B, Paixão MW. Photocatalyzed Intramolecular [2+2] Cycloaddition of N-Alkyl-N-(2-(1-arylvinyl)aryl)cinnamamides. Chemistry 2021; 27:3722-3728. [PMID: 32955792 DOI: 10.1002/chem.202003641] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Indexed: 02/05/2023]
Abstract
N-Alkyl-N-(2-(1-arylvinyl)aryl)cinnamamides are converted into natural product inspired scaffolds via iridium photocatalyzed intramolecular [2+2] photocycloaddition. The protocol has a broad substrate scope, whilst operating under mild reaction conditions. Tethering four components forming a trisubstituted cyclobutane core builds rapidly high molecular complexity. Our approach allows the design and synthesis of a variety of tetrahydrocyclobuta[c]quinolin-3(1H)-ones, in yields ranging between 20-99 %, and with excellent regio- and diastereoselectivity. Moreover, it was demonstrated that the intramolecular [2+2]-cycloaddition of 1,7-enynes-after fragmentation of the cyclobutane ring-leads to enyne-metathesis-like products.
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Affiliation(s)
- Wanderson C de Souza
- Department of Chemistry, Federal University of São Carlos-UFSCar, Centre of Excellence for Research in Sustainable Chemistry, (CERSusChem), São Carlos, São Paulo, Brazil
| | - Bianca T Matsuo
- Department of Chemistry, Federal University of São Carlos-UFSCar, Centre of Excellence for Research in Sustainable Chemistry, (CERSusChem), São Carlos, São Paulo, Brazil
| | - Priscilla M Matos
- Department of Chemistry, Federal University of São Carlos-UFSCar, Centre of Excellence for Research in Sustainable Chemistry, (CERSusChem), São Carlos, São Paulo, Brazil
| | - José Tiago M Correia
- Department of Chemistry, Federal University of São Carlos-UFSCar, Centre of Excellence for Research in Sustainable Chemistry, (CERSusChem), São Carlos, São Paulo, Brazil
| | - Marilia S Santos
- Department of Chemistry, Federal University of São Carlos-UFSCar, Centre of Excellence for Research in Sustainable Chemistry, (CERSusChem), São Carlos, São Paulo, Brazil.,Institut für Organische Chemie, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany
| | - Burkhard König
- Institut für Organische Chemie, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany
| | - Marcio W Paixão
- Department of Chemistry, Federal University of São Carlos-UFSCar, Centre of Excellence for Research in Sustainable Chemistry, (CERSusChem), São Carlos, São Paulo, Brazil
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22
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Zeng L, Xu J, Zhang D, Yan Z, Cheng G, Rao W, Gao L. Catalytic Enantioselective [2+2] Cycloaddition of α-Halo Acroleins: Construction of Cyclobutanes Containing Two Tetrasubstituted Stereocenters. Angew Chem Int Ed Engl 2020; 59:21890-21894. [PMID: 32803881 DOI: 10.1002/anie.202008465] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 07/31/2020] [Indexed: 01/16/2023]
Abstract
A catalytic enantioselective formal [2+2] cycloaddition between α-halo acroleins and electronically diverse arylalkenes is described. In the presence of (S)-oxazaborolidinium cation as the catalyst, densely functionalized cyclobutanes containing two vicinal tetrasubstituted stereocenters were produced in high yields and high diastereoselectivities with excellent enantioselectivities. Mechanistic studies revealed that the cis isomer could be transformed into the trans isomer via an enantiocontrolled process. A gram-scale reaction of this catalytic method was used to demonstrate its synthetic potential.
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Affiliation(s)
- Lei Zeng
- College of Materials Science and Engineering, Huaqiao University, No.668 Jimei Avenue, Xiamen, Fujian, China
| | - Jingjing Xu
- College of Materials Science and Engineering, Huaqiao University, No.668 Jimei Avenue, Xiamen, Fujian, China
| | - Dongsheng Zhang
- College of Materials Science and Engineering, Huaqiao University, No.668 Jimei Avenue, Xiamen, Fujian, China
| | - Zhongliang Yan
- College of Materials Science and Engineering, Huaqiao University, No.668 Jimei Avenue, Xiamen, Fujian, China
| | - Guolin Cheng
- College of Materials Science and Engineering, Huaqiao University, No.668 Jimei Avenue, Xiamen, Fujian, China
| | - Weidong Rao
- Jiangsu Key Laboratory of Biomass-Based Green Fuels and Chemicals, College of Chemical Engineering, Nanjing Forestry University, Nanjing, China
| | - Lizhu Gao
- College of Materials Science and Engineering, Huaqiao University, No.668 Jimei Avenue, Xiamen, Fujian, China
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23
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Brégent T, Bouillon JP, Poisson T. Copper-Photocatalyzed Contra-Thermodynamic Isomerization of Polarized Alkenes. Org Lett 2020; 22:7688-7693. [PMID: 32945682 DOI: 10.1021/acs.orglett.0c02894] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The contra-thermodynamic isomerization of α- and β-substituted cinnamate derivatives catalyzed by the Cu(OAc)2/rac-BINAP complex under blue light irradiation is reported. The use of an oxazolidinone template, which favored the complexation of the copper catalyst to the substrate, allowed the E → Z isomerization of the catalytically formed chromophore under simple and robust reaction conditions in good to excellent ratios. The mechanism of this process based on the transient formation of a chromophore was also studied.
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Affiliation(s)
- Thibaud Brégent
- Normandie Univ, INSA Rouen, UNIROUEN, CNRS, COBRA (UMR 6014), 76000 Rouen, France
| | | | - Thomas Poisson
- Normandie Univ, INSA Rouen, UNIROUEN, CNRS, COBRA (UMR 6014), 76000 Rouen, France.,Institut Universitaire de France, 1 rue Descartes, 75231 Paris, France
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24
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Zeng L, Xu J, Zhang D, Yan Z, Cheng G, Rao W, Gao L. Catalytic Enantioselective [2+2] Cycloaddition of α‐Halo Acroleins: Construction of Cyclobutanes Containing Two Tetrasubstituted Stereocenters. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202008465] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Lei Zeng
- College of Materials Science and Engineering Huaqiao University No.668 Jimei Avenue Xiamen Fujian China
| | - Jingjing Xu
- College of Materials Science and Engineering Huaqiao University No.668 Jimei Avenue Xiamen Fujian China
| | - Dongsheng Zhang
- College of Materials Science and Engineering Huaqiao University No.668 Jimei Avenue Xiamen Fujian China
| | - Zhongliang Yan
- College of Materials Science and Engineering Huaqiao University No.668 Jimei Avenue Xiamen Fujian China
| | - Guolin Cheng
- College of Materials Science and Engineering Huaqiao University No.668 Jimei Avenue Xiamen Fujian China
| | - Weidong Rao
- Jiangsu Key Laboratory of Biomass-Based Green Fuels and Chemicals College of Chemical Engineering Nanjing Forestry University Nanjing China
| | - Lizhu Gao
- College of Materials Science and Engineering Huaqiao University No.668 Jimei Avenue Xiamen Fujian China
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25
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Schwinger DP, Bach T. Chiral 1,3,2-Oxazaborolidine Catalysts for Enantioselective Photochemical Reactions. Acc Chem Res 2020; 53:1933-1943. [PMID: 32880165 PMCID: PMC7497702 DOI: 10.1021/acs.accounts.0c00379] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Asymmetric synthesis has posed a significant challenge to organic chemists for over a century. Several strategies have been developed to synthesize enantiomerically enriched compounds, which are ubiquitous in the pharmaceutical and agrochemical industries. While many organometallic and organic catalysts have been found to mediate thermal enantioselective reactions, the field of photochemistry lacks similar depth. Recently, chiral 1,3,2-oxazaborolidines have made the transition from Lewis acids that were exclusively applied to thermal reactions to catalysts for enantioselective photochemical reactions. Due to their modular structure, various 1,3,2-oxazaborolidines are readily available and can be easily fitted to a given chemical transformation. Their use holds great promise for future developments in photochemistry. This Account gives an overview of the substrate classes that are known to undergo enantioselective photochemical transformations in the presence of chiral 1,3,2-oxazaborolidines and touches on the catalytic mode of action, on the proposed enantiodifferentiation mechanism, as well as on recent computational studies.Based on the discovery that the presence of Lewis acids enhances the efficiency of coumarin [2 + 2] photocycloadditions, chiral 1,3,2-oxazaborolidines were applied in 2010 for the first time to prepare enantiomerically enriched photoproducts. These Lewis acids were then successfully used in intramolecular [2 + 2] photocycloaddition reactions of 1-alkenoyl-5,6-dihydro-4-pyridones and 3-alkenyloxy-2-cycloalkenones. In the course of this work, it became evident that the chiral 1,3,2-oxazaborolidine must be tailored to the specific reaction; it was shown that both inter- and intramolecular [2 + 2] photocycloadditions of cyclic enones can be conducted enantioselectively, but the aryl rings of the chiral Lewis acids require different substitution patterns. In all [2 + 2] photocycloaddition reactions in which chiral 1,3,2-oxazaborolidines were used as catalysts, the catalyst loading could not be decreased below 50 mol % without sacrificing enantioselectivity due to competitive racemic background reactions. To overcome this constraint, substrates that reacted exclusively when bound to an oxazaborolidine were tested, notably phenanthrene-9-carboxaldehydes and cyclohexa-2,4-dienones. The former substrate class underwent an ortho photocycloaddition, the latter an oxadi-π-methane rearrangement. Several new 1,3,2-oxazaborolidines were designed, and the products were obtained in high enantioselectivity with only 10 mol % of catalyst. Recently, an iridium-based triplet sensitizer was employed to facilitate enantioselective [2 + 2] photocycloadditions of cinnamates with 25 mol % of chiral 1,3,2-oxazaborolidine. In this case, the relatively low catalyst loading was possible because the oxazaborolidine-substrate complex exhibits a lower triplet energy and an improved electronic coupling compared to the uncomplexed substrate, allowing for a selective energy transfer.By synthetic and theoretical studies, it has become evident that chiral 1,3,2-oxazaborolidines are multifaceted catalysts: they change absorption behavior, alter energetic states, and induce chirality. While a diverse set of substrates has been shown to undergo enantioselective photochemical transformations in the presence of chiral 1,3,2-oxazaborolidines either through direct excitation or through triplet sensitization, these catalysts took on different roles for different substrates. Based on the studies presented in this Account, it can be assumed that there are still more photochemical reactions and substrate classes that could profit from chiral 1,3,2-oxazaborolidines.
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Affiliation(s)
- Daniel P. Schwinger
- Department of Chemistry and Catalysis Research Center (CRC), Technical University of Munich, Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Thorsten Bach
- Department of Chemistry and Catalysis Research Center (CRC), Technical University of Munich, Lichtenbergstrasse 4, 85747 Garching, Germany
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26
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Zheng TL, Zhang Y, Gou AL, Cheng F, Liu SZ, Yu L, Cui MY, Xu XT, Zhang K, Wang SH. Au(I)-Catalyzed Cyclization/Semipinacol Rearrangement Reaction of Allenes to Construct Quaternary Carbon-Containing Scaffolds. Org Lett 2020; 22:7073-7077. [PMID: 32886523 DOI: 10.1021/acs.orglett.0c02262] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The development of methods toward the construction of quaternary carbon centers has been a hot topic in recent years. In this work, an Au(I)-catalyzed intramolecular cyclization/semipinacol rearrangement of allene-containing allylic silyl ether was developed to provide a direct strategy for the construction of multisubstituted cyclohexene-type compounds with a quaternary carbon center in moderate to good yields. In particular, this method provides an alternative synthetic strategy for the construction of a multisubstituted spirocyclo[4.5]decane skeleton and may be applied to the synthesis of related bioactive molecules and their derivatives, thus facilitating the corresponding functional studies.
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Affiliation(s)
- Tian-Lu Zheng
- School of Pharmacy & State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, P.R. China
| | - Ye Zhang
- School of Pharmacy & State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, P.R. China
| | - A-Long Gou
- School of Pharmacy & State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, P.R. China
| | - Fu Cheng
- School of Pharmacy & State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, P.R. China
| | - Si-Zhan Liu
- School of Pharmacy & State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, P.R. China
| | - Lan Yu
- School of Pharmacy & State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, P.R. China
| | - Ming-Yue Cui
- School of Pharmacy & State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, P.R. China
| | - Xue-Tao Xu
- School of Biotechnology and Health Science, Wuyi University, Jiangmen 529020, P.R. China
| | - Kun Zhang
- School of Biotechnology and Health Science, Wuyi University, Jiangmen 529020, P.R. China
| | - Shao-Hua Wang
- School of Pharmacy & State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, P.R. China
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27
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Graßl R, Jandl C, Bach T. Visible Light-Mediated Photochemical Reactions of 2-(2'-Alkenyloxy)cycloalk-2-enones. J Org Chem 2020; 85:11426-11439. [PMID: 32806100 PMCID: PMC7476038 DOI: 10.1021/acs.joc.0c01501] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The title compounds were prepared, and their reactivity was studied upon sensitized irradiation at λ = 420 nm. Thioxanthen-9-one was employed as the sensitizer at a loading of 10 mol % in small-scale reactions and of 2.5 mol % on a larger scale. Cyclohex-2-enones substituted by a 2'-propenyloxy, 2'-butenyloxy, 2'-pentenyloxy, or 2'-methyl-2'-propenyloxy group in the 2-position gave the products of an intramolecular [2 + 2] photocycloadditon. The reaction proceeded with high regioselectivity (crossed product) and perfect diastereoselectivity (nine examples, 34-99% yield). If the olefin in the tether was trisubstituted (3'-methyl-2'-butenyloxy), no cycloaddition was observed. Rather, a cyclization with subsequent hydrogen abstraction occurred (three examples, 65-86% yield). The results are consistent with a reaction course via a triplet enone intermediate and the formation of a 1,4-diradical by an initial cyclization. The analogous cyclopent-2-enones were less prone to an intramolecular reaction. Instead, decomposition or intermolecular [2 + 2] photocycloaddition reactions prevailed. In the latter event, two main products were identified (three examples, 30-43% yield), resulting either from a head-to-head [2 + 2]-photodimerization or from a twofold [2 + 2] photocycloaddition of the enone to the olefin. The latter reaction sequence generated pentacyclic products with a central [1,5]dioxocane ring. The structure assignment of the two product types was corroborated by a single-crystal X-ray analysis.
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Affiliation(s)
- Raphaela Graßl
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany
| | - Christian Jandl
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany
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Li D, Yang Y, Zhang M, Wang L, Xu Y, Yang D, Wang R. Activation of allylic esters in an intramolecular vinylogous kinetic resolution reaction with synergistic magnesium catalysts. Nat Commun 2020; 11:2559. [PMID: 32444612 PMCID: PMC7244749 DOI: 10.1038/s41467-020-16486-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 05/05/2020] [Indexed: 11/29/2022] Open
Abstract
Kinetic resolution (KR) of racemic starting materials is a powerful and practical alternative to prepare valuable enantiomerically enriched compounds. A magnesium-catalyzed kinetic resolution based on a designed intramolecular vinylogous Michael reaction is disclosed. Here we show a synergistic catalytic strategy based on the development of chiral ligands. Substrates containing linear allylic ester structures are designed and synthesized to construct key [6.6.5]-tricyclic chiral skeletons via this kinetic resolution process. Detailed mechanistic studies reveal a rational mechanism for the current intramolecular vinylogous KR reaction. The desired direct intramolecular asymmetric vinylogous Michael reaction of linear allylic esters is realized in high efficiency and enantioselectivity with the synergistic catalytic system. Kinetic resolution allows to obtain enantioenriched compounds from racemic mixtures. Here, the authors report a synergistic magnesium catalyst promoting kinetic resolution of an intramolecular vinylogous Michael reaction to access [6.6.5]-tricyclic chiral skeletons.
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Affiliation(s)
- Dan Li
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Institute of Drug Design & Synthesis, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Yuling Yang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Institute of Drug Design & Synthesis, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Minmin Zhang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Institute of Drug Design & Synthesis, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Linqing Wang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Institute of Drug Design & Synthesis, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Yingfan Xu
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Institute of Drug Design & Synthesis, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Dongxu Yang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Institute of Drug Design & Synthesis, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, China.
| | - Rui Wang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Institute of Drug Design & Synthesis, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, China.
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Zhang Y, Zheng TL, Cheng F, Dai KL, Zhang K, Ma AJ, Zhang FM, Zhang XM, Wang SH, Tu YQ. Facile access to diverse all-carbon quaternary center containing spirobicycles by exploring a tandem Castro-Stephens coupling/acyloxy shift/cyclization/semipinacol rearrangement sequence. Chem Sci 2020; 11:3878-3884. [PMID: 34122856 PMCID: PMC8152660 DOI: 10.1039/d0sc00102c] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Efficient combination of two or more reactions into a practically useful purification free sequence is of great significance for the achievement of structural complexity and diversity, and an important approach for the development of new synthetic strategies that are industrially step-economic and environmentally friendly. In this work, a facile and efficient method for the construction of highly functionalized spirocyclo[4.5]decane derivatives containing a synthetically challenging quaternary carbon center has been successfully developed through the realization of a tandem Castro–Stephens coupling/1,3-acyloxy shift/cyclization/semipinacol rearrangement sequence. Thus a series of multi-substituted spirocyclo[4.5]decane and functionalized cyclohexane skeletons with a phenyl-substituted quaternary carbon center have been constructed using this method as illustrated by 24 examples in moderate to good yields. The major advantages of this method over the known strategies are better transformation efficiency (four consecutive transformations in one tandem reaction), product complexity and diversity. As a support of its potential application, a quick construction of the key tetracyclic diterpene skeleton of waihoensene has been achieved. An efficient construction of spirocyclo[4.5]decane derivatives is developed via a Castro–Stephens coupling/1,3-acyloxy shift/cyclization/semipinacol rearrangement sequence.![]()
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Affiliation(s)
- Ye Zhang
- State Key Laboratory of Applied Organic Chemistry, School of Pharmacy, Lanzhou University Lanzhou 730000 P. R. China
| | - Tian-Lu Zheng
- State Key Laboratory of Applied Organic Chemistry, School of Pharmacy, Lanzhou University Lanzhou 730000 P. R. China
| | - Fu Cheng
- State Key Laboratory of Applied Organic Chemistry, School of Pharmacy, Lanzhou University Lanzhou 730000 P. R. China
| | - Kun-Long Dai
- State Key Laboratory of Applied Organic Chemistry, School of Pharmacy, Lanzhou University Lanzhou 730000 P. R. China
| | - Kun Zhang
- School of Biotechnology and Health Science, Wuyi University Jiangmen 529020 P. R. China
| | - Ai-Jun Ma
- School of Biotechnology and Health Science, Wuyi University Jiangmen 529020 P. R. China
| | - Fu-Min Zhang
- State Key Laboratory of Applied Organic Chemistry, School of Pharmacy, Lanzhou University Lanzhou 730000 P. R. China
| | - Xiao-Ming Zhang
- State Key Laboratory of Applied Organic Chemistry, School of Pharmacy, Lanzhou University Lanzhou 730000 P. R. China
| | - Shao-Hua Wang
- State Key Laboratory of Applied Organic Chemistry, School of Pharmacy, Lanzhou University Lanzhou 730000 P. R. China .,School of Biotechnology and Health Science, Wuyi University Jiangmen 529020 P. R. China
| | - Yong-Qiang Tu
- State Key Laboratory of Applied Organic Chemistry, School of Pharmacy, Lanzhou University Lanzhou 730000 P. R. China .,School of Chemistry and Chemical Engineering, Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs, Shanghai Jiao Tong University Shanghai 200240 P. R. China
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30
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Affiliation(s)
- Géraldine Masson
- Institut de Chimie des Substances Naturelles CNRS UPR, 2301; Université Paris-Sud; Université Paris-Saclay; av. de la Terrasse 1 91198 Gif-sur-Yvette Cedex France
| | - Burkhard König
- Department of Organic Chemistry; University of Regensburg; Universitätsstraße 31 93053 Regensburg Germany
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31
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Wen KG, Peng YY, Zeng XP. Advances in the catalytic asymmetric synthesis of quaternary carbon containing cyclobutanes. Org Chem Front 2020. [DOI: 10.1039/d0qo00685h] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The advances in the catalytic asymmetric synthesis of quaternary carbon containing cyclobutanes are described.
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Affiliation(s)
- Kai-Ge Wen
- Key Laboratory of Small Functional Organic Molecule
- Ministry of Education and Jiangxi Key Laboratory of Green Chemistry
- College of Chemistry and Chemical Engineering
- Jiangxi Normal University
- Nanchang
| | - Yi-Yuan Peng
- Key Laboratory of Small Functional Organic Molecule
- Ministry of Education and Jiangxi Key Laboratory of Green Chemistry
- College of Chemistry and Chemical Engineering
- Jiangxi Normal University
- Nanchang
| | - Xing-Ping Zeng
- Key Laboratory of Small Functional Organic Molecule
- Ministry of Education and Jiangxi Key Laboratory of Green Chemistry
- College of Chemistry and Chemical Engineering
- Jiangxi Normal University
- Nanchang
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32
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Takagi R, Tabuchi C. Enantioselective intramolecular [2 + 2] photocycloaddition using phosphoric acid as a chiral template. Org Biomol Chem 2020; 18:9261-9267. [PMID: 33150919 DOI: 10.1039/d0ob02054k] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The enantioselective intramolecular [2 + 2] photocycloaddition of 4-bishomoally-2-quinolone (quinolinone) using phosphoric acid as a chiral template has been developed. Mechanistic studies using several NMR measurement techniques and density functional theory (DFT) calculations indicate that π-π interactions between the phenyl ring on phosphoric acid and quinolinone play important roles in the 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.
| | - Chihiro Tabuchi
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan.
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33
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Leverenz M, Merten C, Dreuw A, Bach T. Lewis Acid Catalyzed Enantioselective Photochemical Rearrangements on the Singlet Potential Energy Surface. J Am Chem Soc 2019; 141:20053-20057. [PMID: 31814393 PMCID: PMC6935867 DOI: 10.1021/jacs.9b12068] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
![]()
The oxadi-π-methane rearrangement of 2,4-cyclohexadienones
to bicyclic ketones was found to proceed with high enantioselectivity
(92–97% ee) in the presence of catalytic amounts
of a chiral Lewis acid (15 examples, 52–80% yield). A notable
feature of the transformation is the fact that it proceeds on the
singlet hypersurface and that no triplet intermediates are involved.
Rapid racemic background reactions were therefore avoided, and the
catalyst loading could be kept low (10 mol %). Computational studies
suggest that the enantioselectivity is determined within a Lewis acid
bound singlet intermediate via a conical intersection. The utility
of the method was demonstrated by a concise synthesis of the natural
product trans-chrysanthemic acid.
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Affiliation(s)
- Malte Leverenz
- Department Chemie and Catalysis Research Center (CRC) , Technische Universität München , Lichtenbergstraße 4 , 85747 Garching , Germany
| | - Christian Merten
- Fakultät für Chemie und Biochemie , Ruhr-Universität Bochum , Universitätsstraße 150 , 44801 Bochum , Germany
| | - Andreas Dreuw
- Interdisciplinary Center for Scientific Computing , Ruprecht-Karls Universität , Im Neuenheimer Feld 205A , 69120 Heidelberg , 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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Stegbauer S, Jeremias N, Jandl C, Bach T. Reversal of reaction type selectivity by Lewis acid coordination: the ortho photocycloaddition of 1- and 2-naphthaldehyde. Chem Sci 2019; 10:8566-8570. [PMID: 31803430 PMCID: PMC6839505 DOI: 10.1039/c9sc03315g] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 07/26/2019] [Indexed: 11/26/2022] Open
Abstract
The value of a specific substrate class for synthetic applications is greatly enhanced if different types of reactions can be performed selectively upon a judicious choice of reaction conditions. In the present study it was shown that the typical photochemical behaviour of naphthaldehydes is completely altered in the presence of Lewis acids. Without Lewis acids, reactions at the carbonyl group are exclusively observed while Lewis acids facilitate a visible light-mediated cycloaddition at the arene core providing access to products of aromatic C-H functionalization via cyclobutane intermediates.
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Affiliation(s)
- Simone Stegbauer
- Department Chemie and Catalysis Research Center (CRC) , Technische Universität München , 85747 Garching , Germany . ; ; Tel: +49 89 28913330
| | - Noah Jeremias
- Department Chemie and Catalysis Research Center (CRC) , Technische Universität München , 85747 Garching , Germany . ; ; Tel: +49 89 28913330
| | - Christian Jandl
- Department Chemie and Catalysis Research Center (CRC) , Technische Universität München , 85747 Garching , Germany . ; ; Tel: +49 89 28913330
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC) , Technische Universität München , 85747 Garching , Germany . ; ; Tel: +49 89 28913330
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35
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Zech A, Jandl C, Bach T. Concise Access to the Skeleton of Protoilludane Sesquiterpenes through a Photochemical Reaction Cascade: Total Synthesis of Atlanticone C. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201908619] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Andreas Zech
- Department Chemie and Catalysis Research Center (CRC) Technische Universität München Lichtenbergstr. 4 85747 Garching Germany
| | - Christian Jandl
- Department Chemie and Catalysis Research Center (CRC) Technische Universität München Lichtenbergstr. 4 85747 Garching Germany
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC) Technische Universität München Lichtenbergstr. 4 85747 Garching Germany
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36
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Zech A, Jandl C, Bach T. Concise Access to the Skeleton of Protoilludane Sesquiterpenes through a Photochemical Reaction Cascade: Total Synthesis of Atlanticone C. Angew Chem Int Ed Engl 2019; 58:14629-14632. [PMID: 31478314 PMCID: PMC7687024 DOI: 10.1002/anie.201908619] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Indexed: 01/03/2023]
Abstract
In a single photochemical operation (λ≥350 nm) an easily accessible indanone derivative was converted into a structurally complex precursor of the protoilludane sesquiterpenes. The product (60 % yield) contains all 15 carbon atoms of the skeleton in the required connectivity and was transformed into the natural product atlanticone C (9 steps, 6 % overall yield). In addition, it was shown that other protoilludanes, such as Δ6 -protoilludene and paesslerin A, can be prepared in a concise fashion via the photochemical key intermediate. The photochemical reaction cascade comprises an ortho photocycloaddition, a thermal disrotatory ring opening and a regioselective disrotatory [4π] photocyclization.
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Affiliation(s)
- Andreas Zech
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstr. 4, 85747, Garching, Germany
| | - Christian Jandl
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstr. 4, 85747, Garching, Germany
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, Lichtenbergstr. 4, 85747, Garching, Germany
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37
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Sheng B, Vo Y, Lan P, Gardiner MG, Banwell MG, Sun P. Direct and Metal-Catalyzed Photochemical Dimerization of the Phthalide (Z)-Ligustilide Leading to Both [2 + 2] and [4 + 2] Cycloadducts: Application to Total Syntheses of Tokinolides A–C and Riligustilide. Org Lett 2019; 21:6295-6299. [DOI: 10.1021/acs.orglett.9b02172] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Bingbing Sheng
- Institute for Advanced and Applied Chemical Synthesis, Jinan University, Zhuhai, 519070, China
| | - Yen Vo
- Research School of Chemistry, Institute of Advanced Studies, The Australian National University, Canberra, ACT 2601, Australia
| | - Ping Lan
- Institute for Advanced and Applied Chemical Synthesis, Jinan University, Zhuhai, 519070, China
| | - Michael G. Gardiner
- Research School of Chemistry, Institute of Advanced Studies, The Australian National University, Canberra, ACT 2601, Australia
| | - Martin G. Banwell
- Institute for Advanced and Applied Chemical Synthesis, Jinan University, Zhuhai, 519070, China
- Research School of Chemistry, Institute of Advanced Studies, The Australian National University, Canberra, ACT 2601, Australia
| | - Pinghua Sun
- Institute for Advanced and Applied Chemical Synthesis, Jinan University, Zhuhai, 519070, China
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38
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Poplata S, Bauer A, Storch G, Bach T. Intramolecular [2+2] Photocycloaddition of Cyclic Enones: Selectivity Control by Lewis Acids and Mechanistic Implications. Chemistry 2019; 25:8135-8148. [PMID: 30983074 PMCID: PMC6618137 DOI: 10.1002/chem.201901304] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Indexed: 11/16/2022]
Abstract
The intramolecular [2+2] photocycloaddition of 3‐alkenyl‐2‐cycloalkenones was performed in an enantioselective fashion (nine representative examples, 54–86 % yield, 76–96 % ee) upon irradiation at λ=366 nm in the presence of an AlBr3‐activated oxazaborolidine as the Lewis acid. An extensive screening of proline‐derived oxazaborolidines showed that the enantioface differentiation depends strongly on the nature of the aryl group at the 3‐position of the heterocycle. DFT calculations of the Lewis acid–substrate complex indicate that attractive dispersion forces may be responsible for a change of the binding mode. The catalytic [2+2] photocycloaddition was shown to proceed on the triplet hypersurface with a quantum yield of 0.05. The positive effect of Lewis acids on the outcome of a given intramolecular [2+2] photocycloaddition was illustrated by optimizing the key step in a concise total synthesis of the sesquiterpene (±)‐italicene.
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Affiliation(s)
- Saner Poplata
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, 85747, Garching, Germany
| | - Andreas Bauer
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, 85747, Garching, Germany
| | - Golo Storch
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, 85747, Garching, Germany
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC), Technische Universität München, 85747, Garching, Germany
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