Diastereoselective Synthesis of Spiro[indoline‐3,7′‐pyrrolo[1,2‐a]azepines] via Sequential [3+2] Cycloaddition and Ring Expansion Reaction

Abstract

AbstractSpiro[indoline‐3,7′‐pyrrolo[1,2‐a]azepines] were conveniently synthesized in satisfactory yields and with high diastereoselectivity from three‐component reaction of L‐proline, isatins and chalcones and sequential reaction with dimethyl but‐2‐ynedioate or methyl propiolate in refluxing methanol. The ferrocenyl‐chalcones and dibenzylideneacetones were also successfully used in this one‐pot two‐step reaction to give novel ferrocenyl and styryl‐substituted spiro compounds. The reaction mechanism included domino [3+2] cycloadddtition reaction of azomethine ylide with chalcone and ring‐expansion reaction of in situ generated spiro[indoline‐3,3′‐pyrrolizine] with electron‐deficient alkynes.