Bromotrichloromethane → (R)-methyl 2-(1-(tert-butoxycarbonylamino)ethyl)oxazole-4-carboxylate

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Reaction Steps

In a round-bottomed flask, 2-((R)-1-tert-butoxycarbonylamino-ethyl)-4,5-dihydro-oxazole-4-carboxylic acid methyl ester (337 mg, 1.18 mmol) was dissolved in dichloromethane (11 ml). The solution was cooled to −16° C. (NaCl/ice bath) and DBU (0.35 ml, 2.32 mmol) was added. After 5 min, bromotrichloromethane (0.13 ml, 1.33 mmol) was added and the reaction mixture was allowed slowly to warm to room temperature and stirred for 4 days. The reaction was quenched with 0.1 M aqueous HCl and extracted with EtOAc (2×). The combined organic layers were washed with water and brine then dried over sodium sulfate, filtered and concentrated. The residue was chromatographed over silica gel with EtOAc/hexanes (gradient 0-30% EtOAc) to afford 152 mg (48%) of 2-((R)-1-tert-butoxycarbonylamino-ethyl)-oxazole-4-carboxylic acid methyl ester as an off-white solid.

Provenance & Evidence