Grignard Addition to Imines Derived from Isatine: A Method for the Asymmetric Synthesis of Quaternary 3-Aminooxindoles

Addition of Grignard reagents to chiral imines derived from isatine afforded chiral, optically enriched 3-substituted 3-aminooxindoles in satisfactory yields and diastereoisomeric ratios. A general protocol is described for the addition of alkyl, alkenyl, and aryl Grignard reagents. In one case, the absolute configuration at C3 was determined and the selective N-deprotection was described, enabling further synthetic transformations of the reaction product.