6-fluoro-1,3-dihydro-2,1-benzothiazole 2,2-dioxide

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a stirred solution of 1,3-dihydro-6-fluoro-2,1-benzisothiazole-2,2-dioxide (2.57 g) in anhydrous pyridine (8 ml) was added ethyl chloroformate (1.79 g) at 0° C. under N2 atmosphere. The mixture was stirred for 30 minutes and concentrated in vacuo. Cold hydrochloric acid was added to the precipitate (pH=6). The resulting solution was extracted with ethyl acetate. The organic layer was washed with water and dried over magnesium sulfate. The crude product was purified by silica gel column chromatography (methylene chloride-ethyl acetate 95:5) to give 1-ethoxycarbonyl-1,3-dihydro-6-fluoro-2,1-benzisothiazole 2,2-dioxide (3.1 g). concentrated in vacuo Cold hydrochloric acid was added to the precipitate (pH=6) The resulting solution was extracted with ethyl acetate The organic layer was washed with water dried over magnesium sulfate The crude product was purified by silica gel column chromatography (methylene chloride-ethyl acetate 95:5)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 2-amino-4-fluorobenzylsulfonate (11.0 g) was added to phosphorous oxychloride (100 ml) at 50° C. and the mixture was heated under reflux for 6 hours. The reaction mixture was concentrated in vacuo and the resulting grease was poured into ice-water mixture. A sodium hydroxide solution was added to the mixture at 0° C. until the mixture was basic. Insoluble material was filtered off and washed with water. The filtrate was treated with aqueous hydrochloric acid solution (pH=2.5). The crude product was separated by filtration. Ethyl acetate was added to the precipitate and the insoluble material was filtered off. The filtrate was concentrated in vacuo, to give 1,3-dihydro-6-fluoro-2,1-benzisothiazole 2,2-dioxide (3.2 g) the mixture was heated under reflux for 6 hours The reaction mixture was concentrated in vacuo the resulting grease was poured into ice-water mixture A sodium hydroxide solution was added to the mixture at 0° C. until the mixture Insoluble material was filtered off washed with water The filtrate was treated with aqueous hydrochloric acid solution (pH=2.5) The crude product was separated by filtration Ethyl acetate was added to the precipitate the insoluble material was filtered off The filtrate was concentrated in vacuo