Electrophilic Alkene Sulfenylation with Alkyl Sulfinates

Abstract

An electrophilic alkene sulfenylation using alkyl sulfinates as readily available sulfur sources has been developed under mild HI activation. Terminal and 1,2-disubstituted alkenes, including cyclic substrates, predominantly undergo electrophilic addition to afford β-alkoxysulfides with high regio-and stereoselectivity. In contrast, 1,1-diarylethenes favor electrophilic substitution to give alkenyl sulfides selectively. Control experiments and Hammett analyses reveal that alkyl sulfinates serve as precursors to sulfur(II) electrophiles and that episulfonium ion formation constitutes the rate-determining step. These findings establish a systematical mechanistic framework for substrate-dependent divergence between electrophilic addition and substitution pathways.