The development of double axially chiral phosphoric acids and their catalytic transfer hydrogenation of quinolines

(Chemical Equation Presented) Building a better scaffold: Low loadings (0.2-1 mol%) of new double axially chiral phosphoric acid catalysts 1 based on bisbinol scaffold were used for asymmetric transfer hydrogenation. 2-Aryl- and 2-alkyl-substituted quinolines gave tetrahydroquinolines in excellent yields and with up to 98% ee and 2,3-disubstituted tetrahydroquinolines were prepared in high diastereo- and enantioselectivities (up to > 20:1 and 92% ee).