Convenient synthesis of functionalized spiro[indoline-3,2′-pyrrolizines] or spiro[indoline-3,3′-pyrrolidines] via multicomponent reactions

Abstract

A general and practical route for the in situ generation of a new type of azomethine ylide and its sequential 1,3-dipolar cycloaddition reaction was successfully established. The three-component reaction of secondary α-amino acids including proline, sarcosine, thiazolidine-4-carboxylic acid with dialkyl acetylenedicarboxylate and 3-methyleneoxindoles in refluxing ethanol afforded the functionalized spiro[indoline-3,2'-pyrrolizines], spiro[indoline-3,3'-pyrrolidines] and spiro[indoline-3,6'-pyrrolo[1,2-c]thiazoles] in good yields and with high diastereoselectivity. Furthermore, similar multicomponent reactions using primary α-amino acids such as glycine, alanine and phenylalanine resulted in the corresponding (spiro[indoline-3,3'-pyrrolidine]-1'-yl)maleates.