Triethylamine → Methyl 5-cyclopropyl-3-(2,6-dichlorophenyl)-1,2-oxazole-4-carboxylate

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Reaction Steps

Triethylamine (1.82 L, 12.84 mol) is added to 3-cyclopropyl-3-oxo-propionic acid methyl ester (913 g, 6.42 mol) and the mixture is stirred at room temperature for 30 minutes. Then, the mixture is cooled to about 10° C. and a suspension of 2,6-dichloro-benzaldehyde chloro-oxime (1440.9 g, 6.42 mol) in EtOH (3.2 L) is added slowly (the internal temperature does not exceed 24° C.). After the addition, the reaction is stirred overnight at room temperature. The reaction is diluted with EtOAc (5.3 L) and washed with water (1.7 L). The layers are separated and the aqueous layer is extracted with EtOAc (3 L). The combined organics are washed with brine, dried over Na2SO4 (anhyd), filtered and concentrated to about 10% of its total volume. The precipitate formed is filtered, triturated with ether (2 L) and dried under vacuum to obtain title compound as a (1275.36 g, 64% yield) as a white solid. MS (m/e): 312 (M+1).

Provenance & Evidence