The hydrogenation/transfer hydrogenation network: asymmetric hydrogenation of ketones with chiral eta6-arene/N-Tosylethylenediamine-ruthenium(II) catalysts.
Chiral eta6-arene/N-tosylethylenediamine-Ru(II) complexes, known as excellent catalysts for asymmetric transfer hydrogenation of aromatic ketones in basic 2-propanol, can be used for asymmetric hydrogenation using H2 gas. Active catalysts are generated from RuCl[(S,S)-TsNCH(C6H5)CH(C6H5)NH2](eta6-p-cymene) in methanol, but not 2-propanol, or by combination of Ru[(S,S)-TsNCH(C6H5)CH(C6H5)NH](eta6-p-cymene) and CF3SO3H or other non-nucleophilic acids. This method allows, for the first time, asymmetric hydrogenation of simple ketones under acidic conditions. Hydrogenation of base-sensitive 4-chromanone and its derivatives with the S,S catalyst proceeds in methanol with a substrate-to-catalyst molar ratio of 1000-3000 (10 atm) to 7000 (100 atm), giving (S)-4-chromanols with 97% ee quantitatively. The reaction can be achieved even on a 2.4 kg scale. The mechanistic rationale for the catalytic efficiency is presented.
Ohkuma
Takeshi
T
Department of Chemistry and Research Center for Materials Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan.
Utsumi
Noriyuki
N
Tsutsumi
Kunihiko
K
Murata
Kunihiko
K
Sandoval
Christian
C
Noyori
Ryoji
R
D000438:Alcohols / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D006859:Hydrogen / Q000737:chemistry*; D006865:Hydrogenation; D007659:Ketones / Q000737:chemistry*; D008968:Molecular Conformation; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*; D014105:Tosyl Compounds / Q000737:chemistry*
D000438:Alcohols; D007659:Ketones; D009942:Organometallic Compounds; D014105:Tosyl Compounds; D012428:Ruthenium; D006859:Hydrogen