7-chloro-1,1-dioxo-4H-1lambda6,2,4-benzothiadiazin-3-one

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

Procedure: To a stirred suspension of 8.0 g of 7-chloro-3,4-dihydro-3-oxo-2H-1,2,4-benzothiadiazine 1,1-dioxide in 80 g of phosphorus oxychloride is added dropwise 7.4 g of 2,6-lutidine, while the mixture is cooled in an ice bath. After the addition, the mixture is heated under reflux for 12 hours and concentrated under reduced pressure. To the residue is added 400 ml of ice water and the resulting mixture is stirred for 30 minutes. The crystalline precipitate is collected by suction filtration, washed with water and then with 2-propanol, and recrystallized from 2-propanol to afford the desired product, m.p. 242°-244° C. while the mixture is cooled in an ice bath After the addition the mixture is heated under reflux for 12 hours concentrated under reduced pressure To the residue is added 400 ml of ice water The crystalline precipitate is collected by suction filtration washed with water with 2-propanol, and recrystallized from 2-propanol

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

Procedure: To a stirred suspension of 8.0 g of 7-chloro-3,4-dihydro-3-oxo-2H-1,2,4-benzothiadiazine 1,1-dioxide in 80 g of phosphorus oxychloride is added dropwise 7.4 g of 2,6-lutidine, while the mixture is cooled in an ice bath. After the addition, the mixture is heated under reflux for 12 hours and concentrated under reduced pressure. To the residue is added 400 ml of ice water and the resulting mixture is stirred for 30 minutes. The crystalline precipitate is collected by suction filtration, washed with water and then with 2-propanol, and recrystallized from 2-propanol to afford the desired product, m.p. 242°-244° C. while the mixture is cooled in an ice bath After the addition the mixture is heated under reflux for 12 hours concentrated under reduced pressure To the residue is added 400 ml of ice water The crystalline precipitate is collected by suction filtration washed with water with 2-propanol, and recrystallized from 2-propanol

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

Procedure: To a stirred suspension of 8.0 g of 7-chloro-3,4-dihydro-3-oxo-2H-1,2,4-benzothiadiazine 1,1-dioxide in 80 g of phosphorus oxychloride is added dropwise 7.4 g of 2,6-lutidine, while the mixture is cooled in an ice bath. After the addition, the mixture is heated under reflux for 12 hours and concentrated under reduced pressure. To the residue is added 400 ml of ice water and the resulting mixture is stirred for 30 minutes. The crystalline precipitate is collected by suction filtration, washed with water and then with 2-propanol, and recrystallized from 2-propanol to afford the desired product, m.p. 242°-244° C. while the mixture is cooled in an ice bath After the addition the mixture is heated under reflux for 12 hours concentrated under reduced pressure To the residue is added 400 ml of ice water The crystalline precipitate is collected by suction filtration washed with water with 2-propanol, and recrystallized from 2-propanol