反应详情

A mixture of 6-fluoro-3-(5-methyl-1,2,4-oxadiazol-3-ylmethyl)-5-nitro-2(3H)-benzothiazolone (3.1 g) and ethanol (40 ml) was prepared. To this mixture was dropwise added a solution of stannous chloride (3.3 mol equivalents per mol equivalent of the nitro compound) in concentrated hydrochloric acid (40 ml), at a temperature of 10° to 15° C. The reaction mixture was stirred at a temperature of 60° to 70° C. for 1.5 hours, and distilled under a reduced pressure to remove the ethanol and the hydrochloric acid therefrom. The resultant residue was admixed with ice (20 g). To the solution thus formed was added dropwise a 25% aqueous potassium hydroxide solution at a temperature of 10° to 15° C. to make the mixture alkaline. The mixture was extracted with dichloromethane (100 ml×2). The dichloromethane extract was washed with water, dried over anhydrous sodium sulfate, and evaporated under reduced pressure to obtain the aimed compound, i.e. 5-amino-6-fluoro-3-(5-methyl-1,2,4-oxadiazol-3-ylmethyl)-2(3H)-benzothiazolone (2.2 g). m.p. 158°-161° C.

1. customwas prepared
2. customat a temperature of 10° to 15° C
3. distillationdistilled under a reduced pressure
4. customto remove the ethanol
5. customTo the solution thus formed
6. extractionThe mixture was extracted with dichloromethane (100 ml×2)
7. extractionThe dichloromethane extract
8. washwas washed with water
9. dry with materialdried over anhydrous sodium sulfate
10. customevaporated under reduced pressure