Enantioselective Michael Addition of Malononitrile to Unsaturated Ketones Catalyzed by Rare-Earth Metal Amides RE[N(SiMe3)2]3 with Phenoxy-Functionalized TsDPEN Ligands.

Abstract

The catalytic enantioselective Michael addition of α,β-unsaturated ketones with malononitrile was well established using rare-earth metal amides RE[N(SiMe3)2]3 (RE = Y, Eu, Sm, Nd, La) with chiral phenoxy-functionalized TsDPEN ligands. The combination of lanthanum amide La[N(SiMe3)2]3 and chiral TsDPEN ligand H3L1 [H3L1 = N-((1R,2R)-2-((3,5-di-tert-butyl-2-hydroxybenzyl)amino)-1,2-diphenylethyl)-4-methylbenzenesulfonamide] in a 1:1.5 molar ratio was proved to be the optimal partner in THF, which provided the desired β-carbonyl dinitriles in excellent yields and good to high enantioselectivities after 12 h at -15 °C.