20485-39-6

584-08-7

609-15-4

20485-39-6

Example 1 Preparation of ethyl 4-methyl-5-oxazolecarboxylate: the compound was prepared according to the method described in French Patent No. 4,522,587. A mixture of 50.0 g (0.337 mol) of ethyl 2-chloroacetoacetate and 42.0 g (0.933 mol) of formamide was stirred and reacted at 120°C to 135°C for 18 hours. Upon completion of the reaction, the reaction mixture was cooled to 10°C using an ice bath. 300 mL of 1N potassium carbonate (K2CO3) solution was slowly added dropwise, taking care to control the rate of gas escape. After dropwise addition, the reaction mixture was mixed with 200 mL of benzene/ether (2:1, v/v), stirred and saturated with sodium chloride (NaCl). The insoluble material was removed by filtration, the organic layer (benzene/ether layer) was separated, washed with water, dried over anhydrous magnesium sulfate (MgSO4) and subsequently concentrated under reduced pressure. The resulting brown residue was distilled through a Kugelrohr distillation apparatus to give 14.8 g of white solid product with a melting point of 31 °C to 33 °C. The yield was 31%; nuclear magnetic resonance hydrogen spectroscopy (1H NMR, CDCl3) data were as follows: δ 8.0 (single peak, 1H, C2H), 4.4 (quartet, J = 7 Hz, 2H, CH2), 2.5 (single peak, 3H, CH3), 1.4 (triple peak, 3H, CH3).