Ring Transformation of 1,2-Thiazetidine 1,1-Dioxides with Lewis Acids: Formation of trans-1,2,3-Oxathiazolidine 2-Oxides and cis-Aziridines.

Abstract Treatment of 1,2-thiazetidine 1,1-dioxides (β-sultams) bearing a poor migratory substituent at C-3 with Lewis acids such as EtAlCl 2 and AlCl 3 provided trans -1,2,3-oxathiazolidine 2-oxides and/or cis -aziridines via the C-S bond cleavage and recyclization. cis -Aziridines and/or ketones were provided from the reactions of 3-aryl-β-sultams with SnCl 4 , depending on the migratory aptitude of the C-3 aryl substituent and configuration of C-3 and C-4 groups.