Unprecedented Halide Dependence on Catalytic Asymmetric Hydrogenation of 2‐Aryl‐ and 2‐Alkyl‐Substituted Quinolinium Salts by Using Ir Complexes with Difluorphos and Halide Ligands

• Published in: Chemistry : a European journal Vol. 15; no. 39; pp. 9990 - 9994
• Main Authors: Tadaoka, Hiroshi, Cartigny, Damien, Nagano, Takuto, Gosavi, Tushar, Ayad, Tahar, Genêt, Jean‐Pierre, Ohshima, Takashi, Ratovelomanana‐Vidal, Virginie, Mashima, Kazushi
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY‐VCH Verlag 05.10.2009; Wiley; Wiley-VCH Verlag
• Subjects: asymmetric synthesis; Chemistry; Chemistry, Multidisciplinary; enantioselectivity; hydrogenation; iridium; Physical Sciences; quinolines; Science & Technology; BETA-HYDROXY ESTERS; STEREOSELECTIVE HYDROGENATION; HETEROAROMATIC-COMPOUNDS; ACYCLIC IMINES; iridium; HIGHLY ENANTIOSELECTIVE HYDROGENATION; asymmetric synthesis; IRIDIUM COMPLEXES; ENHANCEMENT; SYNTHETIC APPLICATIONS; enantioselectivity hydrogenation; quinolines; CYCLIC IMINES; METOLACHLOR
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.200901477

A better way: Halide ligands bound to an iridium atom are the key to achieving high catalytic activity and enantioselectivity on asymmetric hydrogenation of 2‐aryl‐ and 2‐alkyl‐substituted quinolinium salts. The reaction was catalyzed by a cationic dinuclear iridium(III) complex with difluorphos and chloride or bromide ligands and gave the corresponding 2‐substituted 1,2,3,4‐tetrahydroquinolines in high enantioselectivities (up to 95 % ee; see scheme, difluorphos=[(4,4′‐bi‐2,2‐difluoro‐1,3‐benzodioxole)‐5,5′‐diyl]bis(diphenylphosphine)).