Highly efficient synthesis of chiral quaternary 3-aminooxindoles promoted by zinc(II) chloride via Et2Zn-catalysed addition of Grignard reagents to isaltin-derived N-tert-butanesulfinyl ketimines

A highly efficient and practical approach to chiral quaternary 3-aminooxindoles was developed via Et2Zn catalyzed diastereoselective addition of Grignard reagents to isaltin-derived N-tert-butanesulfinyl ketimines giving good to excellent yields and diastereoselectivities with broad substrates and reagent scopes promoted by zinc(II) chloride.