Catalytic Asymmetric Dearomatization by Visible‐Light‐Activated [2+2] Photocycloaddition. Issue 21 (27th April 2018)

• Record Type: Journal Article
• Authors: Hu, Naifu; Jung, Hoimin; Zheng, Yu; Lee, Juhyeong; Zhang, Lilu; Ullah, Zakir; Xie, Xiulan; Harms, Klaus; Baik, Mu‐Hyun; Meggers, Eric
• Is Part Of: Angewandte Chemie international edition. Volume 57:Issue 21(2018)
• Page Start: 6242
• Page End: 6246
• Publication Date: 2018-04-27
• Subjects: asymmetric catalysis -- cycloaddition -- dearomatization -- photochemistry -- rhodium; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201802891
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: A novel method for the catalytic asymmetric dearomatization by visible‐light‐activated [2+2] photocycloaddition with benzofurans and one example of a benzothiophene is reported, thereby providing chiral tricyclic structures with up to four stereocenters including quaternary stereocenters. The benzofurans and the benzothiophene are functionalized at the 2‐position with a chelating N ‐acylpyrazole moiety which permits the coordination of a visible‐light‐activatable chiral‐at‐rhodium Lewis acid catalyst. Computational molecular modeling revealed the origin of the unusual regioselectivity and identified the heteroatom in the heterocycle to be key for the regiocontrol. Abstract : It all adds up : A catalytic asymmetric dearomatization of benzofurans and one benzothiophene was accomplished by visible‐light‐activated [2+2] photocycloaddition using a chiral‐at‐rhodium Lewis acid catalyst, thereby providing chiral tricyclic structures with up to four stereocenters, including a quaternary stereocenter. Computational modeling revealed the origin of the observed regioselectivity.