反应详情

To stirred triethyl orthoformate (35.0 mL, 210 mmol) was added methyl 3-amino-4,5-dihydroxybenzoate hydrochloride (6.30 g, 28.7 mmol). The stirred suspension was refluxed for 20 min (until a clear solution formed), cooled to room temperature, and poured into hexane (200 mL). The formed precipitate was separated by filtration and vacuum-dried to afford the desired benzoxazole (4.26 g, 22.05 mmol, 77% yield). 1H NMR (400 MHz, DMSO-d6): δ 10.90 (br. s, 1H), 8.79 (s, 1H), 7.80 (d, J=1.3 Hz, 1H), 7.50 (d, J=1.3 Hz, 1H), 3.86 (s, 3H).

1. temperatureThe stirred suspension was refluxed for 20 min (until a clear solution
2. customformed),
3. customThe formed precipitate was separated by filtration
4. customvacuum-dried