Acetic Anhydride → 2-Methyl-thieno[3,2-d][1,3]oxazin-4-one

Participants

Reaction Steps

To a mixture of 3-acetamidothiophene-2-carboxylic acid (15.1 g, 75.67 mmol) and sodium acetate (6.45 g, 78.6 mmol) in dioxane (200 mL) was added acetic anhydride (71 mL, 75.7 mmol). The reaction was refluxed 2 hours, cooled to ambient temperature and partitioned between chloroform and water. Phases were separated and the aqueous layer was extracted with chloroform. The combined organic phase was washed with water and brine, dried over magnesiuym sulfate and concentrated to leave 15.1 g of 2-methyl-thieno[3,2-d][1,3]oxazin-4-one as a brown oil which slowly solidified.

Provenance & Evidence