Water → 6,7-Difluoro-3-(4-nitrophenyl)-2,3-dihydrobenzo[e][1,3]oxazin-4-one

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Reaction Steps

To 4,5-difluoro-2-hydroxy-N-(4-nitrophenyl)benzamide (0.13 g, 0.44 mmol) in toluene (5 ml) was added paraformadehyde (0.3 g, 10 mmol) and p-toluenesulfonic acid (0.01 g, 0.05 mmol) and the reaction heated to 120° C. for 3 hr with azeotropic removal of water. Saturated sodium bicarbonate (10 ml) was added and product extracted with ethyl acetate, dried over anhydrous sodium sulfate and concentrated to give 0.11 mg (81%) of 6,7-difluoro-3-(4-nitrophenyl)-2,3-dihydrobenzo[e][1,3]oxazin-4-one. RP-HPLC: 2.54 min; ES-MS (M+H)+=307.0; 1H-NMR (MeOH-d4) δ (ppm): 5.78 (s, 2 H), 7.04 (dd, 1 H), 7.64 (d, 2 H), 7.82 (dd, 1 H), 8.3 (d, 2 H).

Provenance & Evidence