A clean synthesis of spiro[indoline-3,9′-xanthene]trione derivatives

A simple, clean and efficient method for the synthesis of spiro[indoline-3,9'-xanthene]trione derivatives and spirolacenaphthene-1,9'-xanthene]-1',2,8'(2'H,5'H)-trione by condensation reaction of dimedone and isatins or acenaphthene in aqueous media is reported.