Catalytic asymmetric 1,4-additions of beta-keto esters to nitroalkenes promoted by a bifunctional homobimetallic Co2-Schiff base complex.

Catalytic asymmetric 1,4-addition of beta-keto esters to nitroalkenes is described. 2.5 mol % of a homobimetallic Lewis acid/Brønsted base bifunctional Co2-Schiff base complex smoothly promoted the reaction in excellent yield (up to 99%), diastereoselectivity, and enantioselectivity (up to >30:1 dr and 98% ee). Catalyst loading was successfully reduced to 0.1 mol %. Mechanistic studies suggested that intramolecular cooperative functions of the two Co-metal centers are important for high catalytic activity and stereoselectivity.