反应详情

A mixture of 74.3 g (0.25 mol) of isopropyl 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylate 1,1-dioxide and 25.7 g (0.32 mol) of 2-aminopyridine in 2,700 ml of xylene is maintained under reflux for 20 hours. During this time, approximately one third of the solvent is distilled off and is replaced, and finally the mixture is distilled to a final volume of 1,500 ml. The mixture is cooled to 0°-5° C. and filtered and the product washed with xylene. By crystallization with dichloroethane, 63 g (75%) of a crystalline white product, m.p. 198°-200° C. are obtained.

1. temperatureis maintained
2. temperatureunder reflux for 20 hours
3. distillationDuring this time, approximately one third of the solvent is distilled off
4. distillationfinally the mixture is distilled to a final volume of 1,500 ml
5. temperatureThe mixture is cooled to 0°-5° C.
6. filtrationfiltered
7. washthe product washed with xylene
8. customBy crystallization with dichloroethane, 63 g (75%) of a crystalline white product, m.p. 198°-200° C.
9. customare obtained