Choline chloride and lactic acid: A natural deep eutectic solvent for one-pot rapid construction of spiro[indoline-3,4′-pyrazolo[3,4-b]pyridines]

The application of natural eutectic solvent (NDDES) in organic synthesis has received more and more attention. In this work, a green protocol for one-pot synthesis of spiro[indoline-3,4′-pyrazolo[3,4-b]pyridines] via three-component reactions of 1H-pyrazol-5-amin, isatin and enolizable CH activated compound is achieved by the combination of microwave irradiation with choline chloride and lactic acid based NDDES. This novel method is clean,...