Isatin N,N′-cyclic azomethine imine 1, 3-dipole mediated regio and diastereoselective synthesis of isoxazole-containing spirooxindoles by an abnormal [3 + 2] cycloaddition

Abstract

An abnormal [3 + 2] cycloaddition with isatin N,N′‑cyclic azomethine imines and styrylisoxazoles for the formation of spirocyclic oxindoles via C(sp3)-H activation and C3 umpolung of quaternary oxindoles has been developed. Various isatin N,N′‑cyclic azomethine imines and styrylisoxazoles underwent in a CNC [3 + 2] cycloaddition with wide substrate scope. Numerous bicyclic spiropyrrolidine oxindoles bearing four consecutive stereogenic centres has been synthesized with excellent yield and diastereoselectivity (up to >98:<2) under mild condition.