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-spiroindoline-
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