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 Na2 SO4 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/d×d (1H); 3,78 and 3.75/each s (each 3H); 1.33/s (9H).

Provenance & Evidence