Lithium Hydroxide → 5(S)-(Boc-Amino)-4(S)-hydroxy-6-phenyl-2(R)-[(2,4-dimethoxyphenyl)methyl]hexanoic acid

Participants

Reaction Steps

A solution of 1.58 g (3.47 mmol) of 5(S)-[1(S)-(Boc-amino)-2-phenylethyl]-3(R)-[(2,4-dimethoxyphenyl)methyl]dihydrofuran-2-(3H)-one in 56 ml of ethylene glycol dimethyl ether and 28.2 ml of water is treated, at RT, with 13.87 ml of a 1M solution of LiOH in water, and this mixture is stirred for 1.75 h. After that, the reaction mixture is diluted with ethyl acetate and a little THF and the whole is washed firstly with a mixture consisting of 170.6 ml of sat. ammonium chloride solution and 14.25 ml of 10% citric acid solution (both being cold) and then with saline. The combined aqueous phases are reextracted with ethyl acetate. The combined organic phases are dried over Na2SO4 and evaporated on a RE at about 30° C. The residue, which is the title compound, is triturated with hexane and filtered off with suction. M.p.: 144°-145° C. TLC Rf (D)=at the start. FAB-MS (M+H)+ =474. HPLC TRet =14.34 min (gradient II). IR(KBr)=u.a. 3420, 3350, 2818, 1686, 1518 and 1508 cm-1. 1H-NMR(CD3OD)=inter alia 7.30-7.09/m (5H); 6.94/d (1H); 6.47/d (1H); 6.37/dxd (1H); 3,78 and 3.75/each s (each 3H); 1.33/s (9H).

Provenance & Evidence