Highly stereoselective conjugate addition and α-alkynylation reaction with electron-deficient alkynes catalyzed by chiral scandium(III) complexes.

The highly Z-selective asymmetric conjugate addition of 3-substituted oxindoles to alkynyl carbonyl compounds has been developed by using scandium complexes of chiral N,N-dioxides under mild conditions. The thermodynamically unstable Z-olefin derivatives were obtained in excellent yields and high enantiomeric and geometric control. The catalyst was also found to be effective in the asymmetric acetylenic substitution reaction of 3-substituted oxindoles, giving excellent enantioselectivities.