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Updated: Sep 14, 2025
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Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions
Published on: July 17, 2020
Photoinduced Asymmetric [4 + 2] Cycloaddition of Benzocyclobutenones with Ketones into 3,4-Dihydroisocoumarins
Hansen Zhao1, Xi Lu1, Liangkun Yang1
1Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610017, P. R. China.
Abstract:
A photoinduced asymmetric catalytic [4 + 2] cycloaddition of benzocyclobutenones with aryl alkyl ketones was realized via C-C single-bond activation, delivering a series of enantioenriched 3,4-dihydroisocoumarins featuring a sterically hindered quaternary stereocenter. This transformation exhibited good functional group tolerance and offered a convenient route for the late-stage modification of several drug molecules. Mechanistic studies revealed that the reaction involved regiospecific C1-C8 bond cleavage of benzocyclobutenones via a chiral Lewis acid-assisted radical addition of triplet state ketones to benzocyclobutenones, followed by intramolecular radical-radical coupling.
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