Enantioselective Construction of Spirooxindole Derivatives: Asymmetric [3+2] Cyclization of Isothiocyanatooxindoles with Allenic Esters or 2-Butynedioic Acid Diesters

A novel Cinchona alkaloid-derived organocatalyst having stronger hydrogen-bonding donors that catalyzes the asymmetric [3+2] cycloaddition of 3-isothiocyanatooxindoles with allenic esters or 2-butynedioic acid diesters has been developed, affording functionalized spirooxindole derivatives in high yields along with good to excellent enantioselectivities under mild conditions. We also found that by changing the ratio of the substrates, different spirooxindole derivatives could be obtained in high yields along with good to excellent enantioselectivities.