Ethyl 3-methyl-4-oxo-4,7-dihydroisothiazolo[5,4-b]pyridine-5-carboxylate → 3-Methyl-4-oxo-4,7-dihydroisothiazolo[5,4-b]pyridine-5-carboxylic acid

HRID 1056808Notes

Reaction equation

HRID 1056808 reaction equation
[CH3:1][C:2]1[C:10]2[C:9](=[O:11])[C:8]([C:12]([O:14]CC)=[O:13])=[CH:7][NH:6][C:5]=2[S:4][N:3]=1>[OH-].[Na+]>[CH3:1][C:2]1[C:10]2[C:9](=[O:11])[C:8]([C:12]([OH:14])=[O:13])=[CH:7][NH:6][C:5]=2[S:4][N:3]=1

Participants

3

Reactant 1

HCID 135741684Ethyl 3-methyl-4-oxo-4,7-dihydroisothiazolo[5,4-b]pyridine-5-carboxylate

Product 1

HCID 1357416853-Methyl-4-oxo-4,7-dihydroisothiazolo[5,4-b]pyridine-5-carboxylic acidYield 94.5%

Reagents, catalysts & solvents 1

HCID 14798Sodium HydroxideSolvent

Procedure

Ethyl 3-methyl-4-oxo-4,7-dihydroisothiazolo[5,4-b]pyridine-5-carboxylate (18 g, 75.55 mmol) was suspended in 2 N NaOH (100 mL) and the mixture was heated at reflux for 3 h. After hydrolysis was complete, the reaction was filtered to yield a dark brown solid. The solid was washed with water (100 mL) and acetone (50 mL), then air dried to provide 3-methyl-4-oxo-4,7-dihydroisothiazolo[5,4-b]pyridine-5-carboxylic acid as a dark brown powder (15 g, 79% yield). LC/MS m/z 210.8 [M+H]+, retention time 0.67 min (RP-C18, 10-99% CH3CN/0.05% TFA over 3 min). 1H NMR (400 MHz, DMSO-d6) δ 8.92 (s, 1H), 2.75 (s, 3H).

Workup

  1. temperaturethe mixture was heated
  2. temperatureat reflux for 3 h
  3. customAfter hydrolysis
  4. filtrationthe reaction was filtered
  5. customto yield a dark brown solid
  6. washThe solid was washed with water (100 mL) and acetone (50 mL)
  7. customair dried

Sources & evidence

ORD record
ord-458c01ab92bc4966b1b1aa062130e382
Source dataset
uspto-grants-2016_07
Patent number
US09399648B2

Reaction notes

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