Synthesis of 1-substituted 5-acetyl (ethoxycarbonyl)-2,3-dihydropyrazolo- [3,4-b]pyridin-3-ones

摘要

1-Substituted 5-aminopyrazol-3-ones react selectively with ethoxymethylidene β-dicarbonyl compounds (3-ethoxymethylidene-2,4- pentanedione, diethyl 2-ethoxymethylidenemalonate, and ethyl 2-ethoxy-methylideneacetoacetate) with the formation of dihydropyrazolylaminomethylidene β-dicarbonyl derivatives, which undergo thermal intramolecular cyclization to 5-functionalized dihydro-pyrazolo[3,4-b] pyridin-3-ones.