Enantioselective Construction of CF3-Containing Spirooxindole γ-Lactones via Organocatalytic Asymmetric Michael/Lactonization.

A highly enantioselective Michael/lactonization cascade reaction of 3-hydroxyoxindoles with 3-trifluoroethylidene oxindoles was developed. The use of a cinchona-derived squaramide catalyst is essential in achieving high diastereo- and enantioselectivities. This reaction represents the first example of intramolecular amide C-N bond cleavage and lactonization of 3-hydroxyoxindoles with 3-trifluoroethylidene oxindoles, which provides an efficient and convenient approach to diverse CF3-containing spirooxindole γ-lactones in high yields and good to excellent diastereo- and enantioselectivities.