Electrochemical [4+1] Annulation of N -(Arylsulfonyl)acrylamides with 1,3-Dicarbonyl Compounds via Multiple C–H Functionalization

A general electrochemical intermolecular cascade annulation between N-arylacrylamides and 1,3-dicarbonyl compounds through C(sp3)–H/C(sp2)–H functionalization and 1,4-aryl migration has been developed. This protocol employs 1,3-dicarbonyl compounds as C1 synthons that undergo [4+1] carboannulation, delivering diverse functionalized indanes with two distinct quaternary carbon centers under noble-metal- and external-oxidant-free conditions. Control experiments indicate that the reaction proceeds via a sequential cascade of oxidative C(sp3)–H cleavage to generate an alkyl radical, radical addition across the C═C bond, 1,4-aryl migration, a further oxidative C(sp3)–H cleavage to form another alkyl radical, [4+1] annulation, and deprotonation.