Synthesis of 2-Oxindoles Sharing Vicinal All-Carbon Quaternary Stereocenters via Organocatalytic Aldol Reaction

An organocatalytic enantioselective aldol reaction using paraformaldehyde as C1-unit has been developed for the synthesis of 2-oxindoles sharing vicinal all-carbon quaternary stereocenters. The methodology is eventually employed in the formal total synthesis of (+)-folicanthine (1b).