Highly efficient and enantioselective hydrogenation of quinolines and pyridines with Ir-Difluorphos catalyst.
The combination of the readily available chiral bisphosphine ligand Difluorphos with [Ir(COD)Cl](2) in THF resulted in a highly efficient catalyst system for asymmetric hydrogenation of quinolines at quite low catalyst loadings (0.05-0.002 mol%), affording the corresponding products with high enantioselectivities (up to 96%), excellent catalytic activities (TOF up to 3510 h(-1)) and productivities (TON up to 43000). The same catalyst was also successfully applied to the asymmetric hydrogenation of trisubstituted pyridines with nearly quantitative yields and up to 98% ee. In these two reactions, the addition of I(2) additive is indispensable; but the amount of I(2) has a different effect on catalytic performance.
Tang
Weijun
W
Department of Chemistry, Renmin University of China, Beijing 100872, China.
Sun
Yawei
Y
Lijin Xu
Wang
Tianli
T
Qinghua Fan
Lam
Kim-Hung
KH
Chan
Albert S C
AS
D002384:Catalysis; D006865:Hydrogenation; D007495:Iridium / Q000737:chemistry*; D010720:Phosphines / Q000737:chemistry; D011725:Pyridines / Q000737:chemistry*; D011804:Quinolines / Q000737:chemistry*; D013237:Stereoisomerism; D013379:Substrate Specificity
D010720:Phosphines; D011725:Pyridines; D011804:Quinolines; D007495:Iridium; C023666:pyridine