Abstract
Thioxopyrimidines 4(a–c) were synthesized by using the Biginelli three-component cyclocondensation reaction of an appropriate β-diketone, arylaldehyde, and thiourea. Reaction of thioxopyrimidines 5 with bromomalononitrile under strong basic solution afforded thiazolopyrimidines 7(a–c). On condensation of thiazolopyrimidines 7 with hydroxylamine hydrochloride in acetic acid and in the presence of sodium acetate thiazolodipyrimidines 8(a–b) were obtained. However reaction of 7 with formic acid gave the corresponding pyrazolothiazolopyrimidine 9a.