反应详情

Ruthenium-catalyzed hydrogenation. -- A catalyst solution was prepared in a glove box (O2 content <1 ppm) by dissolving 0.0914 g (0.119 mmol) of Ru(OAc)2 [(S)-BIPHEMP] in 50 ml of methanol and stirring at 20° for 15 minutes. Then, 5.0 g (23.74 mmol) of 2-(p- chlorophenyl)-3-methylcrotonic acid and 23 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 60 bar. The conversion was 100% after 4 hours. The hydrogenation solution was evaporated at 50°/20 mbar and the residue was distilled in a bulb tube oven at 150°/0.2 mbar. There were obtained 4.6 g (92%) of (R)-2-(p-chlorophenyl)-3-methylbutyric acid as a colorless oil which crystallized out at RT; chemical purity 98.8 area %; 90.5% ee; [α]589 =-42.3° (c=1, methanol).

1. customthe catalyst solution prepared
2. additionabove was added
3. customThe autoclave was sealed
4. customwas carried out at 20°
5. stirringwhile stirring and under a constant pressure of 60 bar
6. customafter 4 hours
7. customThe hydrogenation solution was evaporated at 50°/20 mbar
8. distillationthe residue was distilled in a bulb tube oven at 150°/0.2 mbar