Sulfuric Acid → 4,6-Dimethyl-benzo[d]isothiazole-3-carboxylic acid methyl ester

HRID 2175178Notes

Reaction equation

HRID 2175178 reaction equation
[CH3:1][C:2]1[C:7]2[C:8]([C:11]([OH:13])=[O:12])=[N:9][S:10][C:6]=2[CH:5]=[C:4]([CH3:14])[CH:3]=1.OS(O)(=O)=O.[C:20]([O-])(O)=O.[Na+]>CO>[CH3:20][O:12][C:11]([C:8]1[C:7]2[C:2]([CH3:1])=[CH:3][C:4]([CH3:14])=[CH:5][C:6]=2[S:10][N:9]=1)=[O:13]

Participants

5

Reactant 3

HCID 1118Sulfuric AcidHCID 516892Sodium BicarbonateHCID 584973864,6-Dimethylbenzo[d]isothiazole-3-carboxylic acid

Product 1

HCID 584974334,6-Dimethyl-benzo[d]isothiazole-3-carboxylic acid methyl esterYield 94%

Reagents, catalysts & solvents 1

HCID 887MethanolSolvent

Conditions

Temperature
60 °C

Procedure

To a solution of 4,6-dimethyl-benzo[d]isothiazole-3-carboxylic acid (10 mg, 0.048 mmol) in MeOH (5 mL) was added conc. H2SO4 (0.1 mL) at room temperature. The solution was heated up to 60° C. for 24 hours. The solution was cooled and was neutralized with sat. NaHCO3. The solution was extracted with EtOAc. The combined organic layer was dried over MgSO4 and filtered. The filtrate was concentrated and the residue was purified by silica gel flash column chromatography with 20% EtOAc in Hexane as the eluent to afford the title compound (10 mg, 94%) as colorless oil.

Workup

  1. temperatureThe solution was cooled
  2. extractionThe solution was extracted with EtOAc
  3. dry with materialThe combined organic layer was dried over MgSO4
  4. filtrationfiltered
  5. concentrationThe filtrate was concentrated
  6. customthe residue was purified by silica gel flash column chromatography with 20% EtOAc in Hexane as the eluent

Sources & evidence

ORD record
ord-a0ee5fe37ef440cd9ff5f553f978c2cf
Source dataset
uspto-grants-2015_06
Patent number
US09062056B2

Reaction notes

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