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

Participants

Reaction Steps

A catalyst solution was prepared in a glove box (O2 content <1 ppm) at RT by dissolving 0.124 g (0.155 mmol) of Ru(OAc)2[(R)-MeOBIPHEP] in 50 ml of methanol. Then, 30.0 g (154.5 mmol) of 2-(p-fluorophenyl)-3-methylcrotonic acid and 38 ml of methanol were placed in a 185 ml autoclave and the catalyst solution prepared above was added. The autoclave was sealed and the hydrogenation was carried out at 20° while stirring and under a constant pressure of 180 bar. The conversion was 100% after 6 hours. The hydrogenation solution was evaporated at 50°/20 mbar and the residue was distilled in a bulb tube oven at 125°/0.2 mbar. There were obtained 28.04 g (92.5%) of (S)-2-(p-fluorophenyl)-3-methylbutyric acid as a colorless oil which crystallized out at RT; chemical purity 99.9 GC area %; 90% ee.

Provenance & Evidence