反应详情

2.7 g (R)-5-Biphenyl-4-ylmethyl-3-methyl-2-oxo-2,5-dihydro-pyrrole-1-carboxylic acid tert-butyl ester (4-a, R1=Boc) is added to tetrahydrofuran (20 ml). Aqueous lithium hydroxide solution (10 ml, 3 M) is added and the mixture is stirred for 20 h at ambient temperature. The mixture is acidified by addition of phosphoric acid and subsequently diluted by addition of ethyl acetate. The phases are separated and the organic phase is washed with water and then concentrated under reduced pressure. Isopropyl acetate is added to the residue and the mixture is filtered to afford (Z)—(R)-5-Biphenyl-4-yl-4-tert-butoxycarbonylamino-2-methylpent-2-enoic acid (5a, R1=Boc, R2=H, R3=CO2H). 1H NMR (DMSO): 1.28 (9H), 1.85 (3H), 2.78 (2H), 5.07 (1H), 5.92 (1H), 6.96 (1H), 7.30 (2H), 7.35 (1H), 7.46 (2H), 7.56 (2H), 7.63 (2H), 12.65 (1H).

1. customThe phases are separated
2. washthe organic phase is washed with water
3. concentrationconcentrated under reduced pressure
4. additionIsopropyl acetate is added to the residue
5. filtrationthe mixture is filtered