Enantioselective Synthesis of 3,4-Dihydropyrimidin-2(1 H)-ones through Organocatalytic Transfer Hydrogenation of 2-Hydroxypyrimidines.

Chiral phosphoric acid-catalyzed transfer hydrogenation of 2-hydroxypyrimidines has been successfully realized using Hantzsch ester or dihydrophenanthridine as the hydrogen source, furnishing the chiral 3,4-dihydropyrimidin-2(1 H)-ones (DHPMs) with excellent yields and enantioselectivities of ≤99%. Notably, a novel kind of chiral DHPMs with an alkyl stereogenic center can be prepared through highly chemoselective transfer hydrogenation.