A new approach to azapentalenes by an addition–rearrangement sequence: synthesis of fused 1,2,4-thiadiazoles

Abstract

Carbamoylimino substituted thiazolo[3,2-b][1,2,4]thiadiazoles 7 and 8, [1,3,4]thiadiazolo[3,2-b][1,2,4]thiadiazole 9, [1,2,4]thiadiazolo[3,2-b]benzoxazole 10, [1,2,4]thiadiazolo[3,2-b]benzothiazole 11 and [1,2,4]thiadiazolo[2,3-a]benzimidazole 12 are conveniently prepared from 5-chloro1,2,4-thiadiazol-3-(2H)-one 6 and an appropriate 2-aminoazole by an addition–rearrangement sequence.