Combine (S)-2-[N-(t-butoxycarbonyl)-allylamino]-3-phenyl-propioic acid (1.59 g, 5.20 mmol), (2-methoxybenzyl)methylamine (0.79 g, 5.20 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (1.12 g, 5.72 mmol), 1-hydroxybenzotriazole (0.38 g, 2.52 mmol), and diisopropylethylamine (1.34 mL, 6.5 mmol) in dichloromethane (50 mL) and stir for 18 hours. Dilute with ethyl acetate and extract with 1M hydrochloric acid, a saturated aqueous solution of sodium bicarbonate and a saturated aqueous solution of sodium chloride. Dry the separated organic layer over MgSO4, filter and evaporate in vacuo. Chromatograph on silica gel eluting sequentially with 5% ethyl acetate/hexane and 10% ethyl acetate/hexane to give the title compound: TLC Rf =0.55 (silica gel, 30% ethyl acetate/hexane).
