A solution of [(2S)-1-(biphenyl-4-ylcarbonyl)-4-oxopyrrolidin-2-yl]acetic acid (Intermediate 5, 1.50 g, 6.64 mmol), hydroxylamine methyl ether hydrochloride (0.58 g, 6.96 mmol) and triethylamine (1.62 ml, 11.60 mmol) in chloroforme (30 ml) was stirred at RT for 2 days Solvent was removed under reduced pressure and the residue was taken up in ethyl acetate. Organic phase was washed twice with a solution of citric acid 10% and once with brine. Organic phase was then dried on MgSO4, filtered, and concentrated to give [(2S,4EZ)-1-(biphenyl-4-ylcarbonyl)-4-(methoxyimino)pyrrolidin-2-yl]acetic acid as a cream solid (1.14 g). Yield: 45%. HLPC purity: 92%
