C[C:2]1[C:7]2[C:8](=[O:17])[N:9]([CH2:13][C:14]([O-:16])=[O:15])[S:10](=[O:12])(=[O:11])[C:6]=2[CH:5]=[CH:4][CH:3]=1.[CH3:18][O-].[Na+].Cl>CN(C=O)C.O>[OH:17][C:8]1[C:7]2[CH:2]=[CH:3][CH:4]=[CH:5][C:6]=2[S:10](=[O:12])(=[O:11])[NH:9][C:13]=1[C:14]([O:16][CH3:18])=[O:15]In a nitrogen atmosphere, a solution of 30 grams (0.117 moles) of methyl-2,3-dihydro-3-oxo-1,2-benzisothiazoline-2-acetate 1,1-dioxide in 50 ml DMF is added, with stirring, to a suspension of 18.9 grams (0.351 moles) of sodium methoxide in 100 ml DMF over a period of about 5 minutes and the internal temperature is maintained at 15°-30° C. by means of an ice bath. The stirring is continued for 30 minutes at about 30° C. after the completion of the addition. With external cooling, a solution of 35 ml concentrated HCl in 600 ml of water is added, maintaining the internal temperature below 35° C. After this addition, the mixture is cooled to 10° C. and filtered. The filter cake is washed thoroughly with water and the product is dried. Yield is 23.5 grams (78.2%) m.p. 173°-175° C. The total addition and stirring time prior to acidification should be less than 1 hour. For example, if the addition should take 30 minutes the batch should be stirred only an additional 15-20 minutes.
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