MULTICOMPONENT AND REGIOSELECTIVE SYNTHESIS OF DIHYDROPYRAZOLOl,5-aPYRIMIDINES FROM AROMATIC ALDEHYDES, MELDRUM S ACID AND AMINOPYRAZOLE CAN508

摘要

A regioselective synthesis of dihydropyrazolol,5-apyrimidines is reported. The multicomponent reaction of readily available arylaldehydes, Meldrum's acid, and aminopyrazole CAN508 afforded fused pyrazolopyrimidines in high yields. The reaction proceeded regioselectively via initial Michael addition of the exocyclic amino group to arylidene Meldrum's acid intermediate followed by a ring closure at the endocyclic nitrogen of aminopyrazole. The regioselectivity of the reaction was determined by X-ray crystallography.