Oxygen → (S)-2-(4-Fluorophenyl)-3-methylbutyric acid

Reaction equation

[F:1][C:2]1[CH:7]=[CH:6][C:5]([C:8](=[C:12]([CH3:14])[CH3:13])[C:9]([OH:11])=[O:10])=[CH:4][CH:3]=1.C(N(CC)CC)C.O=O>CO>[F:1][C:2]1[CH:3]=[CH:4][C:5]([C@H:8]([CH:12]([CH3:14])[CH3:13])[C:9]([OH:11])=[O:10])=[CH:6][CH:7]=1

Participants

Procedure

1.0 g (5.15 mmol) of 2-(p-fluorophenyl)-3-methylcrotonic acid and 0.52 g (5.15 mmol) of triethylamine were suspended in 6 ml of methanol in a glove box (O2 content <1 ppm) in a 30 ml autoclave at RT and a solution of 4.1 mg (0.0051 mmol) of Ru(OAc)2 ((R)-MeOPIPHEP) in 5 ml of methanol was added as the catalyst. The autoclave was sealed and the hydrogenation was carried out at 20° while stirring and under an initial pressure of 200 bar. The pressure decreased to about 190 bar during the reaction. After a reaction period of 21 hours a sample of the hydrogenation solution was evaporated at 50°/20 mbar and analyzed. There was obtained (S)-2-(p-fluorophenyl)-3-methylbutanoic acid with an ee of 93%.