Synthesis of some new thiazole, thiophene, and 2,3-dihydro-1,3,4-thiadiazole and pyrimidino[1,2-b]indazole derivatives

Hydrazonoyl halides 4a-g reacted with methyl carbodithioate 3 thioanilide 10 to give 1,3,4-thiadiazoles 5a-g and 13a-g, respectively. Thioanilide 10 reacted with omega-bromoacetophenones 14a-e to give the acyclic product 15a-e, which was converted to the thiophenes 16a-e and to the thiazoles 17a-e, respectively. Structures of the newly synthesized compounds were elucidated on the basis of elemental analysis, spectral data, and alternative synthesis route whenever possible.