Catalytic Enantioselective Synthesis of 3,4-Polyfused Oxindoles with Quaternary All-Carbon Stereocenters: A Rh-Catalyzed C–C Activation Approach

The first Rh-catalyzed enantioselective synthesis of a 3,4-polyfused oxindole ring system enabled by carboacylation of acrylic amides based on C–C activation is reported. This transformation provides a new entry to access 3,4-polyfused oxindoles bearing quaternary stereocenters. Tri- to pentacyclic 3,4-fused oxindoles were asymmetrically generated in good yields (up to 95%) with good to excellent enantioselectivity (88%–97% ee). Application in the first total synthesis of xylanigripones A was completed in 6 steps with a 14% overall yield.