Highly efficient, one-pot synthesis of novel bis-spirooxindoles with skeletal diversity via sequential multi-component reaction in PEG-400 as a biodegradable solvent

Abstract

A green and efficient one-pot, sequential, multi-component protocol has been developed for the synthesis of some novel symmetrical bis-spirooxindole derivatives from the reaction of isatins, dihalides, malono derivatives and C–H activated carbonyl compounds or ketene aminal derivatives in the presence of potassium carbonate (K₂CO₃) in polyethylene glycol 400 (PEG-400) as a biodegradable polymeric solvent at room temperature. In this research, a variety of bis-spiro-indoline-pyranopyranes, bis-spiro-indoline-chromenes, bis-spiro-indoline-pyrido-pyrimidines, bis-spiro-indoline-imidazo-pyridines and bis-spiro-indoline-pyridines were obtained with excellent yields within short reaction time and without chromatographic separation.