Acetic Anhydride → Methyl 5-methyl-1,3-oxazole-4-carboxylate

Participants

Reaction Conditions

Reaction Steps

A stirred mixture of 10.0 g of methyl isocyanoacetate, 15.1 g of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 133 ml of anhydrous THF was cooled to 0° C., and a solution of 10.2 g of acetic anhydride in 33 ml of THF was added dropwise over 15 minutes. The mixture was stirred overnight at room temperature and stripped of solvent. The residue was mixed with 250 ml of ethyl acetate, the mixture was washed with water, dried (MgSO4), filtered and stripped of solvent. The residue was chromatographed on silica gel with a 1:1 v:v ethyl acetate/hexane mixture as eluent. The middle fractions gave methyl 5-methyl-4-oxazolecarboxylate (4A) as a white solid, m.p.: 46.5°-47.0° C.

Provenance & Evidence