反应详情

4.3 g of 5-fluoro-salicylamide and 4.7 g of 5-fluorosalicylic acid are boiled under reflux in 50 ml of xylene after addition of 0.3 ml of pyridine. 4.4 ml of thionyl chloride are added in the course of 2 h, the mixture is stirred for a further 1 h and the solvent is then distilled off under reduced pressure. The residue is suspended in 30 ml of ethanol, filtered off and washed with ethanol. After drying, 6-fluoro-2-(5-fluoro-2-hydroxyphenyl)benz[e][1,3]oxazin-4-one is obtained as slightly yellow crystals of m.p. 250-252 C.

1. distillationthe solvent is then distilled off under reduced pressure
2. filtrationfiltered off
3. washwashed with ethanol
4. customAfter drying