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 CFCHNH 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.