Phosphorus oxychloride → Ethyl 2-chloro-4-(5-chloro-2-thienyl)-5-oxazolebutanoate

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Reaction Conditions

Reaction Steps

A mixture of ethyl 4-[4-(5-chloro-2-thienyl)-2-oxo-4-oxazolin-5-yl]butanoate (12.5 g), phosphorus oxychloride (24.5 g) and pyridine (3.16 g) was heated to 120-130° C. and stirred for 45 minutes. The reaction mixture was poured into ice-water (200 ml) and extracted with ethyl acetate (150 ml×2). The organic layer was washed in sequence with a 10% aqueous solution of sodium hydrogen carbonate (100 ml) and a saturated aqueous solution of sodium chloride (100 ml) and dried over anhydrous magnesium sulfate. The organic layer was concentrated, the residue was subjected to silica gel column chromatography, and ethyl 2-chloro-4-(5-chloro-2-thienyl)-5-oxazolebutanoate was obtained as a yellow oil (5.79 g, 48%) from an ethyl acetate-hexane (1:4, v/v)-eluted fraction.

Provenance & Evidence