1
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Schwinger DP, Pickl T, Bach T. Photochemical Isomerization of Cyclohept-1-ene-1-carbaldehyde: Strain-Release Cycloadditions and Ene Reactions. J Org Chem 2023; 88:12844-12852. [PMID: 37578442 DOI: 10.1021/acs.joc.3c01311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Cyclohept-1-ene-1-carbaldehyde undergoes photoinduced E → Z isomerization at λ = 350 nm. The ring strain facilitates Diels-Alder cycloaddiions with 1,3-dienes, [3 + 2] cycloadditions with 1,3-dipoles, and ene reactions with olefins. Products are trans-fused at the cycloheptane core and were obtained in yields of up to 82%. Single crystal X-ray analyses corroborated the constitution and relative configuration of key products. With BF3 as a Lewis acid and 2,3-dimethylbuta-1,3-diene, cyclohept-1-ene-1-carbaldehyde reacted in the dark and rearranged stereoselectively to a tricyclic ketone (87%).
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Affiliation(s)
- Daniel P Schwinger
- Technical University of Munich, TUM School of Natural Sciences, Department of Chemistry and Catalysis Research Center (CRC), Lichtenbergstrasse 4, 85748 Garching, Germany
| | - Thomas Pickl
- Technical University of Munich, TUM School of Natural Sciences, Department of Chemistry and Catalysis Research Center (CRC), Lichtenbergstrasse 4, 85748 Garching, Germany
| | - Thorsten Bach
- Technical University of Munich, TUM School of Natural Sciences, Department of Chemistry and Catalysis Research Center (CRC), Lichtenbergstrasse 4, 85748 Garching, Germany
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2
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Kong L, Yu H, Deng M, Wu F, Chen SC, Luo T. Enantioselective Total Syntheses of Grayanane Diterpenoids and (+)-Kalmanol: Evolution of the Bridgehead Carbocation-Based Cyclization and Late-Stage Functional Group Manipulation Strategies. J Org Chem 2023; 88:6017-6038. [PMID: 37094797 DOI: 10.1021/acs.joc.3c00365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2023]
Abstract
Grayanane diterpenoids contain over 300 highly oxidized and structurally complex members, many of which possess important biological activities. Full details are provided for the development of the concise, enantioselective and divergent total syntheses of grayanane diterpenoids and (+)-kalmanol. The unique 7-endo-trig cyclization based on a bridgehead carbocation was designed and implemented to construct the 5/7/6/5 tetracyclic skeleton, demonstrating the practical value of the bridgehead carbocation-based cyclization strategy. Extensive studies of late-stage functional group manipulation were performed to forge the C1 stereogenic center, during which a photoexcited intramolecular hydrogen atom transfer reaction was discovered and the mechanism was further studied through density functional theory (DFT) calculations. The biomimetic 1,2-rearrangement from the grayanoid skeleton provided a 5/8/5/5 tetracyclic framework and resulted in the first total synthesis of (+)-kalmanol.
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Affiliation(s)
- Lingran Kong
- Key Laboratory of Bioorganic Chemistry and Molecular Engineering, Ministry of Education and Beijing National Laboratory for Molecular Science, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Hang Yu
- Key Laboratory of Bioorganic Chemistry and Molecular Engineering, Ministry of Education and Beijing National Laboratory for Molecular Science, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Mengping Deng
- Key Laboratory of Bioorganic Chemistry and Molecular Engineering, Ministry of Education and Beijing National Laboratory for Molecular Science, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Fanrui Wu
- Key Laboratory of Bioorganic Chemistry and Molecular Engineering, Ministry of Education and Beijing National Laboratory for Molecular Science, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Si-Cong Chen
- Key Laboratory of Bioorganic Chemistry and Molecular Engineering, Ministry of Education and Beijing National Laboratory for Molecular Science, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Tuoping Luo
- Key Laboratory of Bioorganic Chemistry and Molecular Engineering, Ministry of Education and Beijing National Laboratory for Molecular Science, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, Guangdong 518055, China
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3
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Jones B, Solon P, Popescu MV, Du JY, Paton R, Smith MD. Catalytic Enantioselective 6π Photocyclization of Acrylanilides. J Am Chem Soc 2022; 145:171-178. [PMID: 36571763 PMCID: PMC9837842 DOI: 10.1021/jacs.2c09267] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Controlling absolute stereochemistry in catalytic photochemical reactions is generally challenging owing to high rates of background reactivity. Successful strategies broadly rely on selective excitation of the reaction substrate when associated with a chiral catalyst. Recent studies have demonstrated that chiral Lewis acid complexes can enable selective energy transfer from a photosensitizer to facilitate enantioselective triplet state reactions. Here, we apply this approach to the enantioselective catalysis of a 6π photocyclization through the design of an iridium photosensitizer optimized to undergo energy transfer to a reaction substrate only in the presence of a chiral Lewis acid complex. Among a group of iridium(III) sensitizers, enantioselectivity and yield closely correlate with photocatalyst triplet energy within a narrow window enabled by a modest reduction in substrate triplet energy upon binding a scandium/ligand complex. These results demonstrate that photocatalyst tuning offers a means to suppress background reactivity and improve enantioselectivity in photochemical reactions.
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Affiliation(s)
- Benjamin
A. Jones
- Chemistry
Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K.
| | - Pearse Solon
- Chemistry
Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K.
| | - Mihai V. Popescu
- Chemistry
Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K.,Department
of Chemistry, Colorado State University, 1301 Center Avenue, Ft. Collins, Colorado 80523-1872, United States
| | - Ji-Yuan Du
- Chemistry
Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K.
| | - Robert Paton
- Department
of Chemistry, Colorado State University, 1301 Center Avenue, Ft. Collins, Colorado 80523-1872, United States,
| | - Martin D. Smith
- Chemistry
Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K.,
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4
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Lin C, Wang J, Yang K, Liu J, Ma DL, Leung CH, Wang W. Development of a NIR iridium(III) complex for self-calibrated and luminogenic detection of boron trifluoride. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2022; 282:121658. [PMID: 35905613 DOI: 10.1016/j.saa.2022.121658] [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: 05/05/2022] [Revised: 07/18/2022] [Accepted: 07/20/2022] [Indexed: 06/15/2023]
Abstract
Boron trifluoride (BF3) is a potential environmental pollutant, and excess exposure to it may cause human diseases. However, the sensitive, rapid and accurate detection of BF3 for on-site purposes is still a challenge. In this work, we developed the first NIR iridium(III)-based probe with dual emission and a Stokes shift of 370 nm for self-calibrated and luminogenic detection of BF3. This probe exhibited a strong luminescence enhancement at around 650 nm to BF3 (0-100 μM) with almost no change in luminescence at 475 nm, displaying a 220-fold I650 nm/I475 nm enhancement at 100 μM of BF3 with a detection limit of 0.35 μM. Moreover, the probe showed a fast response time of less than 5 s to BF3 along with an obvious color change under UV irradiation for visual detection. Importantly, the desirable photophysical properties of the iridium(III)-based probe can be harnessed for time-resolved detection of BF3 in the presence of the fluorescence background. The applicability of the probe was further verified in an organic solvent waste-spiked system and on a glass pane. This work will provide a solid basis for the development of sensitive and on-site BF3 sensing toolkits for environmental monitoring.
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Affiliation(s)
- Chuankai Lin
- Jiangxi Provincial Key Laboratory of Functional Molecular Materials Chemistry, Jiangxi University of Science and Technology, Ganzhou 341000, China; Institute of Medical Research, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi 710072, China; Northwestern Polytechnical University Chongqing Technology Innovation Center, Chongqing 400000, China
| | - Jing Wang
- Institute of Medical Research, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi 710072, China; Northwestern Polytechnical University Chongqing Technology Innovation Center, Chongqing 400000, China
| | - Kai Yang
- School of Chemistry and Chemical Engineering, Shandong University of Technology, Zibo 255049, China
| | - Jinbiao Liu
- Jiangxi Provincial Key Laboratory of Functional Molecular Materials Chemistry, Jiangxi University of Science and Technology, Ganzhou 341000, China.
| | - Dik-Lung Ma
- Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong Special Administrative Region
| | - Chung-Hang Leung
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Taipa, Macau.
| | - Wanhe Wang
- Institute of Medical Research, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi 710072, China; Northwestern Polytechnical University Chongqing Technology Innovation Center, Chongqing 400000, China.
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5
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Schwinger DP, Peschel MT, Rigotti T, Kabaciński P, Knoll T, Thyrhaug E, Cerullo G, Hauer J, de Vivie-Riedle R, Bach T. Photoinduced B-Cl Bond Fission in Aldehyde-BCl 3 Complexes as a Mechanistic Scenario for C-H Bond Activation. J Am Chem Soc 2022; 144:18927-18937. [PMID: 36205547 DOI: 10.1021/jacs.2c06683] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In concert with carbonyl compounds, Lewis acids have been identified as a versatile class of photocatalysts. Thus far, research has focused on activation of the substrate, either by changing its photophysical properties or by modifying its photochemistry. In this work, we expand the established mode of action by demonstrating that UV photoexcitation of a Lewis acid-base complex can lead to homolytic cleavage of a covalent bond in the Lewis acid. In a study on the complex of benzaldehyde and the Lewis acid BCl3, we found evidence for homolytic B-Cl bond cleavage leading to formation of a borylated ketyl radical and a free chlorine atom only hundreds of femtoseconds after excitation. Both time-dependent density functional theory and transient absorption experiments identify a benzaldehyde-BCl2 cation as the dominant species formed on the nanosecond time scale. The experimentally validated B-Cl bond homolysis was synthetically exploited for a BCl3-mediated hydroalkylation reaction of aromatic aldehydes (19 examples, 42-76% yield). It was found that hydrocarbons undergo addition to the C═O double bond via a radical pathway. The photogenerated chlorine radical abstracts a hydrogen atom from the alkane, and the resulting carbon-centered radical either recombines with the borylated ketyl radical or adds to the ground-state aldehyde-BCl3 complex, releasing a chlorine atom. The existence of a radical chain was corroborated by quantum yield measurements and by theory. The photolytic mechanism described here is based on electron transfer between a bound chlorine and an aromatic π-system on the substrate. Thereby, it avoids the use of redox-active transition metals.
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Affiliation(s)
- Daniel P Schwinger
- Department Chemie and Catalysis Research Center (CRC) School of Natural Sciences, Technische Universität München, D-85747 Garching, Germany
| | - Martin T Peschel
- Department of Chemistry, Ludwig-Maximilians-Universität München, D-81377 München, Germany
| | - Thomas Rigotti
- Department Chemie and Catalysis Research Center (CRC) School of Natural Sciences, Technische Universität München, D-85747 Garching, Germany
| | - Piotr Kabaciński
- IFN-CNR and Dipartimento di Fisica, Politecnico di Milano, I-20133 Milano, Italy
| | - Thomas Knoll
- Department of Chemistry, Ludwig-Maximilians-Universität München, D-81377 München, Germany
| | - Erling Thyrhaug
- Department Chemie and Catalysis Research Center (CRC) School of Natural Sciences, Technische Universität München, D-85747 Garching, Germany
| | - Giulio Cerullo
- IFN-CNR and Dipartimento di Fisica, Politecnico di Milano, I-20133 Milano, Italy
| | - Jürgen Hauer
- Department Chemie and Catalysis Research Center (CRC) School of Natural Sciences, Technische Universität München, D-85747 Garching, Germany
| | - Regina de Vivie-Riedle
- Department of Chemistry, Ludwig-Maximilians-Universität München, D-81377 München, Germany
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC) School of Natural Sciences, Technische Universität München, D-85747 Garching, Germany
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6
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Jeremias N, Peschel MT, Jaschke C, de Vivie-Riedle R, Bach T. Photochemical Ring Contraction of 5,5-Dialkylcyclopent-2-enones and in situ Trapping by Primary Amines. J Org Chem 2022; 88:6294-6303. [PMID: 35786889 DOI: 10.1021/acs.joc.2c01156] [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
If substituted in the 5,5-position, cyclopent-2-enones undergo a smooth photochemical rearrangement to ketenes. A concomitant cyclopropane formation occurs due to a 1,3-shift of the C5 carbon atom from the carbonyl carbon atom (C1) to carbon atom C3. In this study, the cyclopropyl-substituted ketene intermediates were trapped in situ by primary amines providing an efficient entry into 2,2-disubstituted cyclopropaneacetic amides (24 examples, 49-95% yield). A remarkable feature of the reaction is the fact that the photochemical rearrangement can occur from either the first excited singlet (S1) or the respective triplet state (T1). In line with experimental results (triplet quenching, sensitization), XMS-CASPT2 calculations support the existence of efficient reaction pathways to the intermediate ketene both on the singlet and on the triplet hypersurface.
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Affiliation(s)
- Noah Jeremias
- School of Natural Sciences, Department of Chemistry and Catalysis Research Center (CRC), Technical University of Munich, Lichtenbergstrasse 4, 85747 Garching, Germany
| | - Martin T Peschel
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 11, 81377 München, Germany
| | - Constantin Jaschke
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 11, 81377 München, Germany
| | - Regina de Vivie-Riedle
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 11, 81377 München, Germany
| | - Thorsten Bach
- School of Natural Sciences, Department of Chemistry and Catalysis Research Center (CRC), Technical University of Munich, Lichtenbergstrasse 4, 85747 Garching, Germany
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7
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Xiong Y, Großkopf J, Jandl C, Bach T. Visible Light-Mediated Dearomative Hydrogen Atom Abstraction/ Cyclization Cascade of Indoles. Angew Chem Int Ed Engl 2022; 61:e202200555. [PMID: 35213774 PMCID: PMC9314014 DOI: 10.1002/anie.202200555] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Indexed: 11/24/2022]
Abstract
The photochemical synthesis of yet unknown 2‐oxospiro[azetidine‐3,3′‐indolines] (17 examples, 80–95 % yield), 2,4‐dioxospiro[azetidine‐3,3′‐indolines] (eight examples, 87–97 % yield), and 1‐oxo‐1,3‐dihydrospiro[indene‐2,3′‐indolines] (17 examples, 85–97 % yield) is described. Starting from readily accessible 3‐substituted indoles, a dearomatization of the indole core was accomplished upon irradiation at λ=420 nm in the presence of thioxanthen‐9‐one (10 mol%) as the sensitizer. Based on mechanistic evidence (triplet energy determination, deuteration experiments, by‐product analysis) it is proposed that the reaction proceeds by energy transfer via a 1,4‐ or 1,5‐diradical intermediate. The latter intermediates are formed by excited state hydrogen atom transfer from suitable alkyl groups within the C3 substituent to the indole C2 carbon atom. Subsequent ring closure proceeds with pronounced diastereoselectivity to generate a 4‐ or 5‐membered spirocyclic dearomatized product with several options for further functionalization.
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Affiliation(s)
- Yang Xiong
- Department Chemie and Catalysis Research Center (CRC), School of Natural Sciences, Technische Universität München, Lichtenbergstraße 4, 85747, Garching, Germany
| | - Johannes Großkopf
- Department Chemie and Catalysis Research Center (CRC), School of Natural Sciences, Technische Universität München, Lichtenbergstraße 4, 85747, Garching, Germany
| | - Christian Jandl
- Department Chemie and Catalysis Research Center (CRC), School of Natural Sciences, Technische Universität München, Lichtenbergstraße 4, 85747, Garching, Germany
| | - Thorsten Bach
- Department Chemie and Catalysis Research Center (CRC), School of Natural Sciences, Technische Universität München, Lichtenbergstraße 4, 85747, Garching, Germany
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8
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Schwinger DP, Peschel MT, Jaschke C, Jandl C, de Vivie-Riedle R, Bach T. Diels-Alder Reaction of Photochemically Generated ( E)-Cyclohept-2-enones: Diene Scope, Reaction Pathway, and Synthetic Application. J Org Chem 2022; 87:4838-4851. [PMID: 35315664 DOI: 10.1021/acs.joc.2c00186] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Upon irradiation at λ = 350 nm, cyclohept-2-enone undergoes an isomerization to the strained (E)-isomer. The process was studied by XMS-CASPT2 calculations and found to proceed by two competitive reaction channels on either the singlet or the triplet hypersurface. (E)-Cyclohept-2-enone is a reactive dienophile in thermal [4 + 2] cycloaddition reactions with various dienes. Ten different dienes were probed, most of which─except for 1,3-cyclohexadiene─underwent a clean Diels-Alder reaction and gave the respective trans-fused six-membered rings in good yields (68-98%). The reactions with furan were studied in detail, both experimentally and by DLPNO-CCSD(T) calculations. Two diastereoisomers were formed in a ratio of 63/35 with the exo-product prevailing, and the configuration of both diastereoisomers was corroborated by single crystal X-ray crystallography. The outcome of the photoinduced Diels-Alder reaction matched both qualitatively and quantitatively the calculated reaction pathway. Apart from cyclohept-2-enone, five additional cyclic hept-2-enones and cyclooct-2-enone were employed in their (E)-form as dienophiles in the Diels-Alder reaction with 1,3-cyclopentadiene (80-98% yield). The method was eventually applied to a concise total synthesis of racemic trans-α-himachalene (four steps, 14% overall yield).
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Affiliation(s)
- Daniel P Schwinger
- School of Natural Sciences, Department of Chemistry and Catalysis Research Center (CRC), Technical University of Munich, Lichtenbergstr. 4, 85747 Garching, Germany
| | - Martin T Peschel
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 11, 81377 München, Germany
| | - Constantin Jaschke
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 11, 81377 München, Germany
| | - Christian Jandl
- School of Natural Sciences, Department of Chemistry and Catalysis Research Center (CRC), Technical University of Munich, Lichtenbergstr. 4, 85747 Garching, Germany
| | - Regina de Vivie-Riedle
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 11, 81377 München, Germany
| | - Thorsten Bach
- School of Natural Sciences, Department of Chemistry and Catalysis Research Center (CRC), Technical University of Munich, Lichtenbergstr. 4, 85747 Garching, Germany
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9
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Xiong Y, Großkopf J, Jandl C, Bach T. Visible Light‐Mediated Dearomative Hydrogen Atom Abstraction/ Cyclization Cascade of Indoles. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202200555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Yang Xiong
- Technische Universität München: Technische Universitat Munchen Chemistry GERMANY
| | - Johannes Großkopf
- Technische Universität München: Technische Universitat Munchen Chemistry GERMANY
| | - Christian Jandl
- Technische Universität München: Technische Universitat Munchen Chemistry GERMANY
| | - Thorsten Bach
- Technische Universität München Lehrstuhl für Organische Chemie I Lichtenbergstr. 4 85747 Garching GERMANY
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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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Malý P, Brixner T. Fluoreszenz‐detektierte Pump‐Probe‐Spektroskopie. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202102901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Pavel Malý
- Institut für Physikalische und Theoretische Chemie Universität Würzburg Am Hubland 97074 Würzburg Deutschland
| | - Tobias Brixner
- Institut für Physikalische und Theoretische Chemie Universität Würzburg Am Hubland 97074 Würzburg Deutschland
- Center for Nanosystems Chemistry (CNC) Universität Würzburg Theodor-Boveri-Weg 97074 Würzburg Deutschland
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12
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Malý P, Brixner T. Fluorescence-Detected Pump-Probe Spectroscopy. Angew Chem Int Ed Engl 2021; 60:18867-18875. [PMID: 34152074 PMCID: PMC8457154 DOI: 10.1002/anie.202102901] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 06/17/2021] [Indexed: 12/11/2022]
Abstract
We introduce a new approach to transient spectroscopy, fluorescence-detected pump-probe (F-PP) spectroscopy, that overcomes several limitations of traditional PP. F-PP suppresses excited-state absorption, provides background-free detection, removes artifacts resulting from pump-pulse scattering, from non-resonant solvent response, or from coherent pulse overlap, and allows unique extraction of excited-state dynamics under certain conditions. Despite incoherent detection, time resolution of F-PP is given by the duration of the laser pulses, independent of the fluorescence lifetime. We describe the working principle of F-PP and provide its theoretical description. Then we illustrate specific features of F-PP by direct comparison with PP, theoretically and experimentally. For this purpose, we investigate, with both techniques, a molecular squaraine heterodimer, core-shell CdSe/ZnS quantum dots, and fluorescent protein mCherry. F-PP is broadly applicable to chemical systems in various environments and in different spectral regimes.
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Affiliation(s)
- Pavel Malý
- Institut für Physikalische und Theoretische ChemieUniversität WürzburgAm Hubland97074WürzburgGermany
| | - Tobias Brixner
- Institut für Physikalische und Theoretische ChemieUniversität WürzburgAm Hubland97074WürzburgGermany
- Center for Nanosystems Chemistry (CNC)Universität WürzburgTheodor-Boveri-Weg97074WürzburgGermany
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13
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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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