Reversal of Enantioselectivity in the Copper-Aminophenol Sulfonamide Catalyzed Alkynylation of Isatins by Slightly Tuning the Ligand Structure and Basic Additives.

A series of new chiral aminophenol sulfonamide ligands with a monochiral arm has been developed for the first Cu(I) catalyzed enantiodivergent alkynylation of isatins. Dramatic reversal of enantioselectivity was accomplished by slightly tuning the substituted benzenesulfonamide and achiral basic additives. A wide range of both terminal alkynes and isatins are tolerated by this new catalyst system with up to 99% yield and 97% ee.