Abstract 1, 2, 5-Thiadiazole-3-carboxaldehydes 1a-c were prepared by the acid-catalyzed decomposition of 3-azido-methyl-1, 2, 5-thiadiazoles 2a-c in 68-83% yields, respectively. Pyrolysis of 2a and 2b afforded the imidazoles 4a and 4b in low yields. NBS-bromination ...