Asymmetric [3+2] Photocycloadditions of Cyclopropanes with Alkenes or Alkynes through Visible‐Light Excitation of Catalyst‐Bound Substrates. Issue 19 (10th April 2018)

• Record Type: Journal Article
• Authors: Huang, Xiaoqiang; Lin, Jiahui; Shen, Tianqi; Harms, Klaus; Marchini, Marianna; Ceroni, Paola; Meggers, Eric
• Is Part Of: Angewandte Chemie international edition. Volume 57:Issue 19(2018)
• Page Start: 5454
• Page End: 5458
• Publication Date: 2018-04-10
• Subjects: asymmetric catalysis -- cycloadditions -- photoredox catalysis -- cyclopentenes -- cyclopropanes; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201802316
• Languages: English
• ISSNs: 1433-7851

Abstract

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. Abstract : Molecular complexity in a single step : Asymmetric [3+2] photocycloadditions between cyclopropanes and alkenes or alkynes catalyzed by a chiral‐at‐metal rhodium complex are reported. The reactions, enabled by a mild single‐electron reduction of visible‐light‐excited catalyst‐bound substrates, provide access to chiral cyclopentanes and cyclopentenes.