New Convenient Four-Component Synthesis of 6-Amino-2,4-dihydropyrano[2,3-c]pyrazol-5-carbonitriles and One-Pot Synthesis of 6'-Aminospiro[(3H)-indol-3,4'-pyrano[2,3-c]pyrazol]-(1H)-2-on-5'-carbonitriles

摘要

This report describes a new four-component synthesis of substituted and spiro-conjugated 6-amino-2W,4H-pyrano[2,3-c]pyrazol-5-carbonitriles directly from aromatic aldehydes or heterocyclic ketones, malononitrile, β-ketoesters, and hydrazine hydrate. The method provides a convenient one-pot route toward divers 2,4-dihydropyrano[2,3-c]pyrazoles, whereas a modified one-step sequential protocol gives access to spiro[indoline-3,4'-pyrano[2,3-c]pyrazol]-2-ones.