Chiral 1,3-aminosquaramides derived from cis-2-benzamidocyclohexanecarboxylic acid as organocatalysts for asymmetric Michael addition reactions

Herein, chiral 1,3-aminosquaramides derived from cis-2-benzamidocyclohexanecarboxylic acid, which is a chiral β-amino acid derivative, were synthesized and applied as bifunctional organocatalysts for asymmetric Michael addition reaction of 1,3-dicarbonyl compounds to β-nitrostyrenes. The catalyst structure and reaction conditions, such as solvent and temperature, were examined, and then, the optimized organocatalyst was successfully applied to the reaction of 1,3-diketones and 1,3-ketoesters with an enantioselectivity of up to 96%. Plausible transition state was proposed based on the results reported in previous reports and DFT calculations.