Ethanol → (2R,4S)-4-amino-5-(biphenyl-4-yl)-2-methylpentanoic acid ethyl ester hydrochloride

Participants

Reaction Conditions

Reaction Steps

150 g (2R,4S)-5-biphenyl-4-yl-4-tert-butoxycarbonylamino-2-methylpentanoic acid (3-a, R1=BOC, R2=R3=H) are added to 1500 ml ethanol at room temperature. The mixture is then warmed to an internal temperature of 60-70° C. 42.8 ml Thionyl chloride is then added over a period of 1 h to the reaction mixture. The mixture is then stirred for a further 2 h. 810 ml of the solvent is removed by distillation under reduced pressure. 1460 ml Heptane fraction is then added. 1310 ml of solvent is then removed by distillation under reduced pressure. 1460 ml Heptane fraction is then added. 520 ml of solvent is then removed by distillation under reduced pressure. 1460 ml Heptane fraction is then added. The mixture is then cooled to room temperature over a period of 1 h. The mixture is then stirred at room temperature for 2 h. The solid is then collected by filtration. The solid is then washed with heptane fraction (600 ml) and dried to give (2R,4S)-4-amino-5-biphenyl-4-yl-2-methylpentanoic acid ethyl ester hydrochloride (3-a, R1=R2=H, R3=Et). Spectroscopic data as given in Example 9-1 Method 1.

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