Triethylamine → Methyl 2-methyl-4,5-dihydro-1,3-oxazole-4-carboxylate

Triethylamine (5.86 g, 58.01 mmol) was added to a suspension of L-serine methyl hydrochloride (4.5 g, 29.03 mmol) and ethylacetimidate hydrochloride (4.3 g, 34.95 mmol) in dichloromethane (40 mL) at 0° C. over a period of 20 min. The mixture was then stirred at ambient temperature for 18 h. The suspension was filtered and washed with diethyl ether. The solid which precipitated from the filtrate was again filtered and washed with diethyl ether. The resulting filtrate was dried over anhydrous sodium sulfate and concentrated in vacuo to afford methyl 2-methyl-4,5-dihydrooxazole-4-carboxylate (3 g, 72%) as a liquid.