Atom Transfer Radical Addition (ATRA) To Styrenes With Thiosulfonates Enabled By Synergetic Copper/Photoredox Catalysis

Functionalization via an addition reaction on alkenes represents an attractive atom-economic transformation for the construction of complex organic molecules.While 1,2-functionalization1already received a lot of attention,the 1,2-bis-heteroatom introduction has been far less studied.O,O-（Dioxygenation）,N,N-（diamination）,O,N-（oxyamination）,and X,N-（haloamination and haloazidation）as well as S,S-difunctionalization have been reported.This paper combines the characteristics of mild photocatalytic reaction,easy control,and environmental protection.Through the photocatalytic atom transfer radical addition reaction（ATRA）approach,the S,S-difunctionalization of styrenes was realized.A facile and effective access toβ-aryl-β-arylthiyl-ethylsulfones from styrenes and thiosulfonates via a synergetic copper/photoredox catalyzed ATRA strategy is developed.This method can simultaneously introduce sulfonyl（RSO₂-）and sulfenyl（RS-）groups,which are the main scaffolds in natural products,bioactive synthetic molecules,and marketed therapeutics.A variety of functional groups,especially medicinally relevant heteroaryls,could be well tolerated.Besides aryl ethylenes,the challengingα–substituted styrenes could be successfully employed to construct the benzylic quaternary carbon centers.Owing to the mild conditions as well as the high level of substrate compability,the synergetic ATRA could be applied to derivatize bioactive natural products in late stage,and to install fluorophores across alkenes.The mechanistic studies support the essential role of copper catalyst and photoredox conditions,and reveal sulfonyl radicals as the key intermediate in the transformation.