Visible light-mediated NHC and photoredox co-catalyzed 1,2-sulfonylacylation of allenes via acyl and allyl radical cross-coupling

Abstract

Allyl radicals serve as a crucial intermediate in the radical functionalization of fundamental raw materials and have received increasing attention. Despite their significance, radical cross-couplings involving allyl radicals are rare and mainly focus on couplings with aryl or benzyl radical analogs. Herein, we realized radical 1,2-sulfonylacylation of allenes via an unprecedented cross-coupling between an NHC-stabilized acyl radical and a delocalized allyl radical. Cheap and stable sulfinates and readily accessible acyl sources could be installed into allene units with excellent regioselectivity by the cooperation of visible light catalysis and NHC catalysis. This versatile protocol provides an attractive strategy for valuable sulfonyl-containing multi-substituted allyl ketones under extremely mild conditions with broad functional group tolerance, which might open a new avenue for the radical difunctionalization of allenes.