Dimethyl Sulfate → methyl 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylate 1,1-dioxide

Participants

Reaction Conditions

Reaction Steps

To a suspension of 3.5 grams (0.086 moles) of sodium hydroxide in 68 ml DMF, a solution of 20 grams (.078 moles) of methyl 4-hydroxy-2H-1,2-benzothiazine-3-carboxylate 1,1-dioxide is added in 34 ml DMF over a period of about 5 minutes at about 25°C. 11.9 Grams (0.094 moles) of dimethyl sulphate is added over a period of about 30 minutes at a maximum temperature of 30°C. The reaction is stirred for 3 hours at 30°C. and diluted with about 150 ml of water. It is cooled to 15°C., filtered and washed well with water. After drying, there is obtained 20 grams (95%) of product, m.p. 163°-165°C.

Provenance & Evidence