Phosphine-Catalyzed [3+2] Cycloaddition Reactions of Azomethine Imines with Electron-Deficient Alkenes: A Facile Access to Dinitrogen-Fused Heterocycles

An efficient method for the phosphine-catalyzed [3+2] cycloaddition reaction of azomethine imines with diphenylsulfonyl alkenes to give dinitrogen-fused bi- or tricyclic heterocyclic compounds in high yields has been described. Moreover, two phenylsulfonyl groups installed on the heterocyclic products could be conveniently removed or transformed to other functional groups, making the reaction more useful.