Novel Syntheses of 2,3-Dihydro-1,5-benzothiazepin-4(<i>5H</i>)-ones and 2<i>H</i>-1,4-Benzothiazin-3(4<i>H</i>)-ones

Nucleophilic additions of alpha-mercaptoalkanoate esters and beta-mercaptoalkanoate acids to benzoquinone diimines, followed by cyclization with trifluoroacetic acid or 1,3-dicyclohexylcarbodiimide (DCC), provide novel, high-yielding syntheses of 2H-1,4-benzothiazin-3(4H)-ones (3a-f) and 2,3-dihydro-1,5-benzothiazepin-4(5H)-ones (5a-c), respectively.