DBU-Mediated [3+2] Annulation of 3-Hydroxyisoindolinones with Vinylsulfonium Salts: An Efficient Approach to Functionalized Oxazolo[2,3-a]isoindolones

Abstract

A variety of 2,3-dihydrooxazolo[2,3-a]isoindol-5-one derivatives were synthesized by the DBU-mediated cascade [3+2] annulation reaction of 3-hydroxyisoindolinones with vinylsulfonium salts. A broad range of tricyclic isoindolone products were efficiently prepared in moderate to good yields, with the formation of two carbon-heteroatom bonds in a single step. It is operationally simple and amenable to gram-scale synthesis under transition-metal-free conditions, and exhibits a wide substrate scope with good functional group tolerance.