A Quick, Simple and Clean Synthesis of Spiro(indoline‐3,4′‐pyrazolo[4′, 3′:5,6]pyrido[2, 3‐d]pyrimidines) in Water through a Novel One‐Pot Multicomponent Reaction

Abstract

A novel and general protocol for quick, simple and efficient synthesis of spiro [indoline-3, 4'-pyrazolo[4', 3':5,6]pyrido[2, 3-d] pyrimidines] via one-pot three component reactions of isatins, 5-aminopyrazoles and 6-aminouracils or 2,6-diaminopyrimidin-4-one in water catalyzed by para-toluene sulfonic acid monohydrate (p-TSA.H 2 O) under mild reaction conditions has been described. Use of water as the solvent system, application of mild and cost-effective solid p-TSA.H 2 O as organocatalyst, high yield in short reaction time, simple purification process with no chromatographic technique and operational simplicity make the protocol highly attractive.[a] S.

Decade Advance of Isatin in Three‐component Reactions

“…Water is an environmentally benign solvent. The Deka group [31a,b] reported two TsOH‐catalyzed, water‐mediated three component reactions. Condensation, dehydration, nucleophilic addition, and cyclization with the release of ammonia afforded final products (10–90 minutes).…”