Hydrochloric Acid → methyl 4-hydroxy-2H-1,2-benzothiazine-3-carboxylate 1,1-dioxide

HRID 1657397Notes

Reaction equation

HRID 1657397 reaction equation
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]

Participants

6

Reactant 3

HCID 313Hydrochloric AcidHCID 10942334Sodium MethoxideHCID 86733499Methyl-2,3-dihydro-3-oxo-1,2-benzisothiazoline-2-acetate 1,1-dioxide

Product 1

HCID 54676531methyl 4-hydroxy-2H-1,2-benzothiazine-3-carboxylate 1,1-dioxide

Reagents, catalysts & solvents 2

HCID 962WaterSolventHCID 6228DimethylformamideSolvent2×

Conditions

Temperature
10 °C

Procedure

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 acidification 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.

Workup

  1. temperaturethe internal temperature is maintained at 15°-30°C. by means of an ice bath
  2. additionafter the completion of the addition
  3. temperaturemaintaining the internal temperature below 35°C
  4. additionAfter this addition
  5. filtrationfiltered
  6. washThe filter cake is washed thoroughly with water
  7. customthe product is dried
  8. additionThe total addition
  9. waitto acidification should be less than 1 hour
  10. waitshould take 30 minutes
  11. stirringthe batch should be stirred only an additional 15-20 minutes

Sources & evidence

ORD record
ord-91b92f2d3343467eb0a07a9c95f1a8ce
Source dataset
uspto-grants-1976_06
Patent number
US03960856

Reaction notes

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