NOVEL REACTIONS OF N-SULFONYLAMINES WITH 3-DIMETHYLAMINO-2H-AZIRINES - COMPETITIVE FORMATION OF 1,2,5-THIADIAZOLES, 1,2,3-OXATHIAZOLES AND ACRYLAMIDINES - X-RAY MOLECULAR-STRUCTURE OF -5H-1,2-LAMBDA(6),3-OXATHIAZOL-2-YLIDENE)BENZAMIDE

Reaction of 3-dimethylamino-2,2-diphenyl-2H-azirine 3a with N-sulfonyl alkylamines 2a,b provides 1,2,5-thiadiazoles 5a,b, whereas use of N-ca rbonylsulfonylamines 2c,e as reaction partners primarily results in 1, 2,3-oxathiazoles 6a,b which isomerise to the corresponding thiadiazole s 5c,d on treatment with silica gel at room temperature. In contrast, use of 2-alkyl-3-dimethylamino-2-phenyl-2H-azir 3b,c in the reaction w ith the N-sulfonylamide 2c and the N-sulfonylcarbamates 2e,f leads to mixtures of thiadiazoles 5 and oxathiazoles 6 along with isomeric acry lamidines 7.