Enantioselective allylation of ketones catalyzed by N,N'-dioxide and indium(III) complex

Complexes of (S)-pipecolic acid-, L-proline-, and other amino acid-derived N,N'-dioxides coordinated with different metal ions have been investigated in the enantioselective allylation of ketones. A variety of aromatic ketones were found to be suitable substrates in the presence of the L1-In(III) complex, and afforded the corresponding homoallylic alcohols with good enantioselectivites (up to 83% ee) and moderate to high yields (up to 94%). On the basis of the experimental results, a possible catalytic cycle including a transition state has been proposed to explain the origin of the reactivity and asymmetric inductivity, and a bifunctional catalyst was described with Lewis base N-oxide activating tetraallyltin and Lewis acid indium activating ketone.