A novel one pot four-component reaction for the efficient synthesis of spiro[indoline-3,4′-pyrano[2,3-c]pyrazole]-3′-carboxylate and trifluoromethylated spiro[indole-3,4′-pyrano[2,3-c]pyrazole] derivatives using recyclable PEG-400

Abstract

A novel, simple and efficient synthetic protocol has been developed for the synthesis of spiro[indoline-3,4′-pyrano[2,3-c]pyrazole]-3′-carboxylate and trifluoromethylated spiro[indole-3,4′-pyrano[2,3-c]pyrazole] derivatives via a one pot, four-component reaction using recyclable polyethylene glycol (PEG-400). This new protocol produces novel spiro pyranopyrazole derivatives in good to excellent yields, with operational simplicity and recycling of PEG-400. The remarkable features of this methodology are high yields, an easy work-up process, and a greener method that avoids toxic catalyst and hazardous solvents.