Regioselective Synthesis of Some New Pyrazolo[1,5-a]pyrimidines, Pyrazolo[1,5-a]quinazoline and Pyrimido[4,5:3,4]pyrazolo[1,5-a] pyrimidines Containing Thiazole Moiety

A regioselective synthesis of novel pyrazolo[1,5-a]pyrimidines, pyrazolo[1,5-a]quinazoline and pyrimido[4,5:3,4]pyrazolo[1,5-a]pyrimidines incorporating a thiazole moiety was described via the reactions of the versatile, readily accessible 5-amino-3-(phenylamino)-N-(4-phenylthiazol-2-yl)-1H-pyrazole-4-carboxamide 3 with appropriate 1,3-biselectrophilic reagents namely, -diketones, enaminones, and ,-unsaturated cyclic ketone. The newly synthesized compounds were elucidated by elemental analysis, spectral data, and alternative synthetic route whenever possible.