A solution 2-((1R)-1-{2-[(benzyloxy)amino]-2-oxoethyl}-4-cyclohexylbutyl)5-methyl-1,3-oxazole-4-carboxylic acid (Preparation 72) (230 mg, 0.53 mmol), N-methylmorpholine (61 l, 0.56 mmol), 1-hydroxybenzotriazole hydrate (68 mg, 0.53 mmol) and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (107 mg, 0.56 mmol) in dichloromethane (10 ml) was treated with a solution of glycine methyl ester hydrochloride (70 mg, 0.56 mmol) and N-methylmorpholine (61 l, 0.56 mmol) in dichloromethane (2 ml) and stirred at room temperature for 18 hours. The reaction mixture was diluted with dichloromethane and washed with water, saturated sodium hydrogen carbonate solution and brine, dried over anhydrous magnesium sulphate, filtered and the solvent removed under reduced pressure. The residue was purified by column chromatography on silica gel eluting with a gradient system of 100:0:0 (dichloromethane:methanol:ammonia) gradually changing to 98:2:0.2 (dichloromethane:methanol:ammonia) to afford the title compound as a white solid (160 mg).
