Cyclic sulfenamide: versatile template for the synthesis of 1,4-benzothiazepines

Two efficient syntheses of 1,4-benzothiazepines, substituted in the positions 2 and 5, have been achieved either by a ring expansion reaction of cyclic sulfenamides with methylpropiolate or tosylacetylene catalyzed by pyridine, via a postulated allenolate intermediate; or by an α-sulfenylation reaction promoted by diethylamine and a subsequent acid catalyzed condensation reaction.