4H-1,4-Benzothiazin-3-one → 3-oxo-3,4-dihydro-2H-1,4-benzothiazine-6-sulfonyl chloride

HRID 593319Notes

Reaction equation

HRID 593319 reaction equation
[Cl:1][S:2]([OH:5])(=O)=[O:3].[S:6]1[C:11]2[CH:12]=[CH:13][CH:14]=[CH:15][C:10]=2[NH:9][C:8](=[O:16])[CH2:7]1>>[O:16]=[C:8]1[NH:9][C:10]2[CH:15]=[C:14]([S:2]([Cl:1])(=[O:5])=[O:3])[CH:13]=[CH:12][C:11]=2[S:6][CH2:7]1

Participants

3

Reactant 2

HCID 213964H-1,4-Benzothiazin-3-oneHCID 24638Chlorosulfonic acid

Product 1

HCID 218737563-oxo-3,4-dihydro-2H-1,4-benzothiazine-6-sulfonyl chlorideYield 75%

Procedure

Chlorosulfonic acid (55.93 g, 0.48 mole) was added to a 250 mL round bottom flask under nitrogen at 10° C. To this, 4H-benzo[1,4]thiazin-3-one, (20 g, 0.12 mole) was added slowly so that the reaction temperature was maintained below 20° C. during the addition. After addition, the reaction mixture was stirred at room temperature for 1.5 h and then heated to 65° C. for an additional 1 hour. The reaction was subsequently cooled and poured into ice-cold water. A solid precipitate formed and was collected via filtration. The solid was then washed with water and dried to provide 23.6 g of the title compound (75% yield). 1H NMR (CDCl3, 300 MHz): δ 9.08 (br s, NH), 7.72-7.88 (m, 3H, Ar—H), 3.68 (s, 2H, Ar—CH2); m.p.: 165-167° C.; LC-MS (M+1): 263.92

Workup

  1. temperaturewas maintained below 20° C. during the addition
  2. additionAfter addition
  3. temperatureheated to 65° C. for an additional 1 hour
  4. temperatureThe reaction was subsequently cooled
  5. additionpoured into ice-cold water
  6. customA solid precipitate formed
  7. filtrationwas collected via filtration
  8. washThe solid was then washed with water
  9. customdried

Sources & evidence

ORD record
ord-04dd426f40f343e8b9760ea48aff0f31
Source dataset
uspto-grants-2016_01
Patent number
US09242945B2

Reaction notes

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