To a solution of methyl 2-[4-(N-Boc-aminomethyl)benzoylamino]-3-hydroxypropionate (32.0 g, 90.8 mmol) in THF (150 ml) was added Burgess' Reagent (26.0 g, 109 mmol) and 3 Å molecular sieves (1 g). The reaction was allowed to stir at 60° C. for 2 h. The reaction mixture was cooled to room temperature and concentrated in vacuo. The crude product was dissolved in dichloromethane and purified by flash chromatography over silica gel with ethyl acetate/dichloromethane (1/1) to give methyl 2-[4-(N-Boc-aminomethyl)-phenyl]-4,5-dihydrooxazol-4-ylcarboxylate (29.5 g, 88.2 mmol) as a pale tan oil.
