Metal‐Free Sulfonylation of α,β‐Conjugated Systems by Using Sulfonyl Hydrazides

Abstract A facile iodine/ tert ‐butyl hydroperoxide (TBHP)‐mediated protocol has been developed for the formation of C(sp 2 )−SO 2 and C(sp 3 )−SO 2 bonds through a radical pathway and an ionic pathway, respectively. The denitrative sulfono functionalization (DNSF) of β‐nitrostyrenes with arylsulfonyl hydrazides under solvent‐ and base‐free conditions has been described. The DNSF process appears to proceed through an addition–elimination pathway. The sulfonylation of olefins that contain electron‐withdrawing groups was also examined under solvent‐free conditions and afforded the corresponding alkenyl sulfones through the elimination of HI from the β‐sulfonyl iodo intermediate. The hydrosulfonylation of chalcones and β‐nitrostyrenes proceeded in the presence of an organic base in acetonitrile through a sulfa‐Michael addition.