Synthesis of Pyrazolo[1,5-a][1,3,5]triazine, Pyrazolo[1,5-a]pyrimidine, and Imidazo[1,2-b]pyrazole Derivatives Based on Imidazo[2,1-b]thiazole Moiety

摘要

3(5)-Aminopyrazole derivative (6) has been synthesized by the reactions of the versatile unreported 2-cyano-N-(1-(3-methyl-6-phenylimidazo[2,1-b]thiazol-2-yl)ethylidene)acetohydrazide (3) with phenyl isothiocyanate in KOH/DMF solution followed by reaction with methyl iodide and hydrazine hydrate. Reaction of compound 6 with some 1,3-dicarbonyl compounds yielded pyrazolo[1,5-a]pyrimidine derivatives (14-17). Alkylation of compound 6 with various halo reagents, followed by intramolecular cyclization, yielded the corresponding imidazo[1,2-b]pyrazole derivatives 27, 29, 31, and 33. All newly synthesized compounds were elucidated by considering the data of both elemental analysis and spectral data.