反应详情

A solution of (E)-2-[[3-(4-hydroxy-3-methoxyphenyl)-1-oxo-2-propenyl]amino]benzoic acid (0.5 g, 1.6 mmol) in acetic anhydride (3 mL) was heated to reflux and stirred for 3 h. The reaction was cooled to rt and the resulting suspension was diluted with water. The suspension was stirred at rt for 1 h and the precipitate was collected by filtration, providing (E)-2-(4-acetoxy-3-methoxystyryl)-4H-benzo[d][1,3]oxazin-4-one (0.52 g, 97%) as a pale brown solid; mp 185-186° C.; δH (400 MHz, DMSO-d6) 2.63 (s, 3H, COCH3), 3.85 (s, 3H, OCH3), 7.08 (d, J=16.0 Hz, 1H, CH═CHCO), 7.17 (d, J5′,6′=8.0 Hz, 1H, H5′), 7.38 (d, J5′,6′=8.0, 1H, H6′), 7.59 (t, J3,4=J4,5=8.0 Hz, 1H, H4), 7.61 (d, J3,4=8.0 Hz, 1H, H3), 7.63 (s, 1H, H2′), 7.76 (d, J=16.0 Hz, 1H, CH═CHCO), 7.92 (t, J4,5=J5,6=8.0 Hz, 1H, H5), 8.11 (d, J5,6=8.0 Hz, 1H, H6); δC (100 MHz, DMSO-d6) 20.4, 56.0, 111.9, 116.9, 119.5, 121.4, 123.3, 126.6, 128.1, 128.4, 133.5, 136.8, 140.5, 140.9, 146.6, 151.2, 156.8, 168.4; HRMS (ESI) calculated for C19H5NO5 [M+H]+ 338.1023; found 338.1023; νmax 1197, 1214, 1593, 1635, 1748 cm−1.

1. temperatureto reflux
2. stirringThe suspension was stirred at rt for 1 h
3. filtrationthe precipitate was collected by filtration