Synthesis of Spiro[oxindole-3,2′-pyrrolidine] Derivatives from Benzynes and Azomethine Ylides through 1,3-Dipolar Cycloaddition Reactions

A novel synthetic strategy employing benzyne and azomethine ylides for the construction of spiro[oxindole-3,2′-pyrrolidine] derivatives has been achieved in good yields. The ketimines obtained from the condensation of isatins with CF 3 CH 2 NH 2 react with benzyne in the presence of weak bases such as TBAF or TBAT. This mild practical 1,3-dipolar cycloaddition provides an efficient route to access biologically active compounds.