Highly enantio- and diastereoselective construction of spirocyclic oxindoles via a palladium-catalyzed decarboxylative asymmetric [4 + 2] annulation strategy.

Abstract

A palladium-catalyzed decarboxylative asymmetric [4 + 2] annulation of methyleneindolinones with a zwitterionic oxo-1,4-dipole intermediate was successfully developed to access spirocyclic oxindoles bearing two vicinal stereocenters in good yields with high diastereoselectivities and enantioselectivities. This strategy features a broad substrate scope (28 examples), allowing for efficient scale-up. Further selective transformation of the product and preliminary mechanistic studies were conducted.