An asymmetric organocatalytic addition of fluorinated phenyl-sulfonylnitromethane to isatin-derived ketimines was developed. The reaction was efficiently catalyzed by a chiral tertiary amine, cinchonine.
This methodology provides a new type of optically active compound with two adjacent quaternary carbon stereocenters in good yield (up to 96%), with moderate diastereoselectivity (up to 5.7 : 1 dr) and excellent enantioselectivity (up to 98/ 96% ee).