Ring enlargement of eight- and nine-membered cyclic sulfonamide derivatives in reactions with 3-amino-2H-azirines

The reactions of 3-dimethylamino-2H-azirines (1) with 3,4, 5,6-tetrahydro-8 ,9-dimethoxy-2H-1,2-benzothiazocin-3-one 1,1-dioxide (6a) in acetonitrile g ave the correspondingly substituted 3-dimethylamino-4,5,6,7,8,9-hexahydrobe nzo-1-thia-2,5-diazacycloundecen-6-one 1,1-dioxides (8). In the case of the reaction of 1a with 6a, the 3-amino5,6-dihydro-4H-benzothiazocine 1,1-diox ide derivative (9) was termed as a minor product. The structures of the sta rting material (6a), the unexpected 4,5-dimethoxy-2-(3-cyanopropyl)benzenes ulfonyl chloride (7), the novel eleven-membered heterocycles (8a, 8c), and that of 9 were established by X-Ray crystallography. With the nine-membered homologue 2,3,4,5,6,7-hexahydro-9,10-dimethoxy-1,2-benzothiazonin-3-one 1, 1-dioxide (6b), only the most reactive aminoazirine yielded the ring enlarg ed twelve-membered heterocycle (10).