Enantioselective Organocatalytic Three-Component Vinylogous Michael/Aldol Tandem Reaction among 3‑Alkylidene oxindoles, Methyleneindolinones, and Aldehydes

We reported a one-pot enantioselective three-component vinylogous Michael/aldol tandem reaction of prochiral 3-alkylidene oxindoles with methyleneindolinones and aldehydes using bifunctional organocatalysts. A variety of enantioenriched 3,3-disubstituted oxindoles 3 and spirolactones 4 were generated in moderate yields (up to 78%) with high stereoselectivities (up to >20:1 dr, >99% ee). Intriguingly, we observed that the aldol reaction with paraformaldehyde generates 3,3-disubstituted oxindoles 3 bearing a hydroxymethyl group, while the reaction with aliphatic aldehydes generates spirolactones 4.