Methyl L-phenylalaninate hydrochloride → methyl (2S)-2-amino-3-cyclohexylpropanoate hydrochloride
Reaction equation
[ClH:1].[NH2:2][C@H:3]([C:11]([O:13][CH3:14])=[O:12])[CH2:4][C:5]1[CH:10]=[CH:9][CH:8]=[CH:7][CH:6]=1.[H][H]>CO.[Rh]>[ClH:1].[NH2:2][C@@H:3]([CH2:4][CH:5]1[CH2:10][CH2:9][CH2:8][CH2:7][CH2:6]1)[C:11]([O:13][CH3:14])=[O:12]Participants
5
Procedure
L-Phenylalanine, methyl ester, hydrochloride, 292 g (1.35 mol) in about 4 L of methanol is exposed to hydrogen gas in the presence of 10% Rhodium on carbon catalyst. After hydrogen uptake is complete, the catalyst is filtered and the filtrate concentrated under reduced pressure to a volume of about 500 ml. Diethyl ether, about 1 liter, is added to the thick slurry of crystals and the mixture filtered and washed with diethyl ether to afford 288.9 g of (S)-α-aminocyclohexanepropanoic acid, methyl ester, hydrochloride; mp 157°-159° C.; [α]D23 =+21.6° (c=1.09% methanol).