Highly enantioselective Biginelli reaction catalyzed by a simple chiral primary amine catalyst: asymmetric synthesis of dihydropyrimidines

Several chiral primary amines were introduced as organocatalysts for the asymmetric Biginelli reaction. The reaction was performed by using a combined catalyst consisting of a chiral bifunctional primary amine–pyridine 5j and hydrochloric acid in a mixed solvent of 1,4-dioxane/CHCl3 (8/2, v/v) at room temperature. The corresponding dihydropyrimidines were obtained in moderate to high yields with up to >99% ee under mild conditions.