Ethanol → (2R,4S)-2-methyl-4-((2-methylpropan-2-yl)oxycarbonylamino)-5-(4-phenylphenyl)pentanoic acid

Participants

Reaction Conditions

Reaction Steps

10 g (2R,4S)-5-biphenyl-4-yl-4-tert-butoxycarbonylamino-2-methylpentanoic acid (3-a, R1=BOC, R2=R3=H) are added to ethanol (100 ml). The mixture is heated to 65° C. 3 ml of thionyl bromide is then added over 0.5 hour. The mixture is then stirred for a further 1 hour. The ethanol is removed and heptane added. Further azeotropic distillations are performed using heptane to remove any residual ethanol. The solvent is removed in vacuo to afford (2R,4S)-4-amino-5-biphenyl-4-yl-2-methylpentanoic acid ethyl ester hydrobromide (3-a, R1=R2=H, R3=Et). 1H NMR (DMSO): 1.11 (6H), 1.61 (1H), 1.87 (1H), 2.73 (1H), 2.84 (1H), 3.04 (1H), 3.42 (1H), 4.01 (2H), 7.36 (3H), 7.47 (2H), 7.65 (4H), 8.03 (3H). m/z (ES+) 312 ([MH]+, 100%).

Provenance & Evidence