Diphosgene → 1H,2H,4H-thieno(3,2-d)(1,3)oxazine-2,4-dione

Participants

Reaction Conditions

Reaction Steps

Methyl 3-aminothiophene-2-carboxylate (31.0 g, 0.20 mol) was added to a solution of potassium hydroxide (22.68 g, 0.40 mol) in 1 L water. The solution was heated at 90° C. for 2 hours. The solution was then cooled to 0° C. and trichloromethyl chloroformate (35.7 mL, 0.30 mol) was added slowly, maintaining the temperature between 0° C. and 10° C. The solution was stirred at 0° C. for 4 hours, and then allowed to warm up gradually to room temperature and stirred for another 3 hours. The precipitated solid product was collected by vacuum filtration to give 28.5 g (85% yield) 1H-thieno[3,2-d][1,3]oxazine-2,4-dione. 1H-NMR (DMSO-d6) δ 6.94 (d, J=5.0 Hz, 1H), 8.24 (d, J=5.0 Hz, 1H), 12.26 (b, 1H) ppm; EIMS m/z 170 (M+1).

Provenance & Evidence