Highly enantioselective synthesis of both enantiomers of tetrahydroquinoxaline derivatives Ir-catalyzed asymmetric hydrogenation.

A novel Ir-catalyzed asymmetric hydrogenation protocol for the synthesis of chiral tetrahydroquinoxaline (THQ) derivatives has been developed. By simply adjusting the reaction solvent, both enantiomers of mono-substituted chiral THQs could be selectively obtained in high yields with excellent enantioselectivities (toluene/dioxane: up to 93% yield and 98% ee (); EtOH: up to 83% yield and 93% ee ()). For 2,3-disubstituted chiral THQs, the -hydrogenation products were obtained with up to 95% yield, 20 : 1 dr, and 94% ee.