Chemoselective Syntheses of γ-Butyrolactams Using Vinyl Sulfilimines and Dichloroketene

Reactions between vinyl sulfilimines and dichloroketene generated in situ from trichloroacetyl chloride in the presence of zinc−copper couple give mixtures of α-dichloro-γ-butyrolactams and α-dichloro-γ-butyrolactone imines. Fine-tuning of substituents within vinyl sulfilimines results in reactions with good chemoselectivity and yield for lactams.