A new convenient four-component synthesis of 6-amino-2H, 4H-pyrano[2,3-c]pyrazole-5-carbonitriles and one-pot synthesis of 6 ′-amino-5-cyano-1,2-dihydrospiro-[(3H)-indole-3,4 ′-(4 ′H)-pyrano[2,3-c]pyrazol]-2-ones

A new convenient method for the synthesis of 6-amino-2 H ,4 H -pyrano[2,3- c ]pyrazole-5-carbonitriles, namely, four-component condensation of carbonyl compounds (aromatic aldehydes, heterocyclic ketones), malononitrile, β-keto esters, and hydrazine hydrate in ethanol in the presence of triethylamine as a catalyst, which occurs selectively, is developed. One-pot two-step modification of this method is proposed for the synthesis of spiro[(3 H )-indole-3,4 ′-(4′ H )-pyrano[2,3- c ]pyrazol]-2-ones.