Asymmetric synthesis of chiral tricyclic 3,4-dihydropyrimidin-2-thione derivatives catalyzed by chiral imidodiphosphoric acid

Abstract

The asymmetric synthesis of 3,4-dihydropyrimidin-2-(1H)-one thioacetals was achieved for the first time using a chiral imidodiphosphoric acid catalyst. The Biginelli reaction involving aromatic aldehydes, thiourea, and 1,3-cyclohexanedione as a multi-component reaction was conducted in ethyl acetate at 40 °C with a chiral imidodiphosphoric acid catalyst. Under mild conditions, a series of chiral polycyclic 3,4-dihydropyrimidin-2-(1H)-one thioacetals were obtained with high yields and excellent enantioselectivity (up to 99% ee).