Unprecedented formation of spiro[indoline-3,7′-pyrrolo[1,2-a]azepine] from multicomponent reaction of L-proline, isatin and but-2-ynedioate

The three-component reaction of alpha-amino acids such as L-proline or thiazolidine-4-carboxylic acid, isatins and dialkyl but-2-ynedioates proceeded with normal 1,3-dipolar cycloaddition reaction of azomethine ylide to give spiro[indoline-3,3'-pyrrolizines]. More importantly, the reaction of alpha-amino acid, and isatins with two molecular dialkyl but-2-ynedioates in methanol afforded unprecedented spiro[indoline-3,7'-pyrrolo[1,2-a]-azepines] as main products.