F[C:2]1[CH:7]=[CH:6][C:5]([N+:8]([O-:10])=[O:9])=[CH:4][CH:3]=1.[NH2:11][C@H:12]([C:16]([OH:18])=[O:17])[CH:13]([CH3:15])[CH3:14].C(=O)(O)[O-].[Na+].C(=O)([O-])[O-].[Na+].[Na+].O(C1C=C(C=CC=1)CBr)C1C=CC=CC=1>C(O)C.O.CN(C)C=O>[N+:8]([C:5]1[CH:6]=[CH:7][C:2]([NH:11][C@H:12]([C:16]([OH:18])=[O:17])[CH:13]([CH3:15])[CH3:14])=[CH:3][CH:4]=1)([O-:10])=[O:9]A mixture of 10 g of 4-fluoronitrobenzene, 5 g of valine and 10 g of sodium bicarbonate is dissolved in 200 ml of ethanol and 100 ml of water. The reaction mixture is refluxed for 3 hours and cooled. Excess 4-fluoronitrobenzene is removed by ether extraction and the aqueous phase is brought to pH 3 to 4 with hydrochloric acid. The oily precipitate is extracted with methylene chloride. After drying and removal of solvent, the residue is treated with 3 equivalents of sodium carbonate and 1 equivalent of m-phenoxybenzyl bromide in dimethylformamide as solvent. After stirring 24 hours the mixture is diluted with water and extracted with ether. The organic phase is washed with water, dried and the solvent removed. The crude ester is purified by preparative TLC to give the m-phenoxybenzyl ester of N-(p-nitrophenyl)valine.
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