反应详情

5 g (3R,5S)-5-biphenyl-4-ylmethyl-3-methylpyrrolidin-2-one of example 6 were mixed with a mixture of acetic acid and concentrated hydrochloric acid (50 ml ratio 1:1) and stirred under reflux for about 20 hours. The solution was then concentrated under vacuum and the residue crystallised from acetic acid/ethyl acetate to yield 4.7 g of (2R,4S)-4-amino-5-biphenyl-4-yl-2-methylpentanoic acid hydrochloride (3-a, R1=R2=R3=H). 1H-NMR (DMSO): 1.10 (3H, s, CH3); 1.58 (1H, m, 3-CHH); 1.88 (1H, m, CHH); 2.64 (1H, m, 4-CH); 2.88 (1H, dd, 5-CHH); 3.01 (1H, dd, 5-CHH); 3.45 (1H, m, 2-CH); 7.38 (3H, m, aromatic); 7.47 (2H, m, aromatic); 7.66 (4H, m, aromatic); 8.07 (2H, s, NH); 12.25 (1H, s, CO2H). m/z: 284 (MH+, 100%); 267 (25); 249 (47); 221 (13); 193 (24).

1. temperatureunder reflux for about 20 hours
2. concentrationThe solution was then concentrated under vacuum
3. customthe residue crystallised from acetic acid/ethyl acetate