Hydrochloric Acid → 6-Bromo-2-phenylimidazo[1,2-a]pyridine-7-carboxylic acid

HRID 872244Notes

Reaction equation

HRID 872244 reaction equation
[Br:1][C:2]1[C:3]([C:17]([O:19]C)=[O:18])=[CH:4][C:5]2[N:6]([CH:8]=[C:9]([C:11]3[CH:16]=[CH:15][CH:14]=[CH:13][CH:12]=3)[N:10]=2)[CH:7]=1.[OH-].[K+].Cl>CO>[Br:1][C:2]1[C:3]([C:17]([OH:19])=[O:18])=[CH:4][C:5]2[N:6]([CH:8]=[C:9]([C:11]3[CH:16]=[CH:15][CH:14]=[CH:13][CH:12]=3)[N:10]=2)[CH:7]=1

Participants

5

Reactant 3

HCID 313Hydrochloric AcidHCID 14797Potassium HydroxideHCID 67041599Methyl 6-bromo-2-phenylimidazo[1,2-a]pyridine-7-carboxylate

Product 1

HCID 670418506-Bromo-2-phenylimidazo[1,2-a]pyridine-7-carboxylic acidYield 73.9%

Reagents, catalysts & solvents 1

HCID 887MethanolSolvent

Procedure

A 50 mL round bottomed flask was charged with methyl 6-bromo-2-phenylimidazo[1,2-a]pyridine-7-carboxylate (400 mg, 1.21 mmol) and suspended in methanol (12.1 mL). To that stirring solution was added 3.0M potassium hydroxide (0.805 mL, 2.42 mmol). The flask was fitted with a reflux condenser and placed in an oil bath preheated to 70° C. After 2.5 hours, LCMS showed clean and complete conversion of the starting material to a major peak with the desired mass (m/z=318 [M+H]+). The mixture was cooled to room temperature and 1.0N HCl was added. The reaction mixture was cooled in an ice bath and a pink solid formed. After 30 minutes, the solids were filtered and dried under high vacuum overnight. 6-Bromo-2-phenylimidazo[1,2-a]pyridine-7-carboxylic acid (283 mg, 0.892 mmol, 73.9% yield) was recovered as a pink solid. 1H NMR (400 MHz, DMSO-d6) ppm 9.04 (1H, s), 8.51 (1H, s), 8.09 (1H, s), 7.96-8.03 (2H, m), 7.45-7.54 (2H, m), 7.35-7.43 (1H, m) Mass found 318 [M+H]+.

Workup

  1. customThe flask was fitted with a reflux condenser
  2. customplaced in an oil bath
  3. custompreheated to 70° C
  4. temperatureThe reaction mixture was cooled in an ice bath
  5. customa pink solid formed
  6. waitAfter 30 minutes
  7. filtrationthe solids were filtered
  8. customdried under high vacuum overnight

Sources & evidence

ORD record
ord-75e7a5dc2c81451f93c0b2dad3e1b47c
Source dataset
uspto-grants-2015_03
Patent number
US08975276B2

Reaction notes

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