3‑Amino Oxindole Schiff Base as Synthon for Enantioselective Preparation of Spiro[oxindol-3,2′-pyrrol] from a Michael/Cyclization Reaction Catalyzed by a Bifunctional Cinchona

A new and crucial synthon of 3-((diphenylmethylene)-amino)-oxindole
was designed and synthesized, for which an organocatalytic and enantioselective
Michael/cyclization reaction with a terminal vinyl ketone catalyzed
by a cinchona base was disclosed. A wide variety (28 examples) of
almost all new chiral spiro­[oxindol-3,2′-pyrrols] were prepared
in excellent yields (up to 99%) with excellent enantioselectivities
(95–99% ee), of which a typical chiral spiro product was further
reduced to chiral spiro­[oxindole-3,2′-pyrrolidine].