Asymmetric [3+2] Photocycloadditions of Cyclopropanes with Alkenes or Alkynes through Visible‐Light Excitation of Catalyst‐Bound Substrates |
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| Authors: | Xiaoqiang Huang Jiahui Lin Tianqi Shen Dr Klaus Harms Dr Marianna Marchini Prof Dr Paola Ceroni Prof Dr Eric Meggers |
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| Affiliation: | 1. Fachbereich Chemie, Philipps-Universit?t Marburg, Marburg, Germany;2. Department of Chemistry “Giacomo Ciamician”, University of Bologna, Bologna, Italy |
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| Abstract: | The herein reported visible‐light‐activated catalytic asymmetric 3+2] photocycloadditions between cyclopropanes and alkenes or alkynes provide access to chiral cyclopentanes and cyclopentenes, respectively, in 63–99 % yields and with excellent enantioselectivities of up to >99 % ee. The reactions are catalyzed by a single bis‐cyclometalated chiral‐at‐metal rhodium complex (2–8 mol %) which after coordination to the cyclopropane generates the visible‐light‐absorbing complex, lowers the reduction potential of the cyclopropane, and provides the asymmetric induction and overall stereocontrol. Enabled by a mild single‐electron‐transfer reduction of directly photoexcited catalyst/substrate complexes, the presented transformations expand the scope of catalytic asymmetric photocycloadditions to simple mono‐acceptor‐substituted cyclopropanes affording previously inaccessible chiral cyclopentane and cyclopentene derivatives. |
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| Keywords: | asymmetric catalysis cycloadditions photoredox catalysis cyclopentenes cyclopropanes |
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