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Short Paper | Regular issue | Vol 89, No. 8, 2014, pp.1892-1904
Published online, 16th June, 2014
DOI: 10.3987/COM-14-13026
■ Multicomponent and Regioselective Synthesis of Dihydropyrazolo[1,5-a]pyrimidines from Aromatic Aldehydes, Meldrum’s Acid, and Aminopyrazole CAN508

Lukáš Jedinák, Vladimír Kryštof, Zdeněk Trávníček, and Petr Cankař*

*Department of Organic Chemistry, Palacký University, 17. listopadu 12, 77146 Olomouc, Czech Republic

Abstract

A regioselective synthesis of dihydropyrazolo[1,5-a]pyrimidines 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.