Formaldehyde → 3-(4-Methoxybenzyl)6,7-difluor-2,3-dihydrobenzo[e][1,3]oxazin-4-one

Participants

Reaction Steps

To a toluene solution (25 mL) of N-(4-methoxybenzyl)-4,5-difluoro-2-hydroxybenzamide (1.5 g, 5 mmol) was added paraformaldehyde (0.450 g, 15 mmol) and para-toluenesulfonic acid (0.01 g, 0.05 mmol) and the reaction heated to 110° C. for 3 hr with azeotropic removal of water. Saturated sodium bicarbonate (50 ml) was added and product extracted with ethyl acetate, dried over anhydrous sodium sulfate and concentrated to give 1.3 g (86%) of 3-(4-methoxybenzyl)6,7-difluor-2,3-dihydrobenzo[e][1,3]oxazin-4-one. RP-HPLC: 2.64 min; ES-MS (M+H)+=307.0; 1H-NMR (MeOH-d4) δ (ppm): 7.8 (dd, 1 H), 7.4 (d, 2 H), 6.8 (d, 2 H), 5.1 (s, 2 H), 4.6 (s, 2 H), 3.8 (s, 3 H).

Provenance & Evidence