Bromine → 3-Bromoimidazo[1,2-A]pyridine-7-carbaldehyde

HRID 985535Notes

Reaction equation

HRID 985535 reaction equation
[N:1]1[CH:2]=[CH:3][N:4]2[CH:9]=[CH:8][C:7]([CH:10]=[O:11])=[CH:6][C:5]=12.C([O-])(=O)C.[Na+].[Br:17]Br.S([O-])([O-])=O.[Na+].[Na+]>[Br-].[K+].CO>[NH3:1].[Br:17][C:3]1[N:4]2[CH:9]=[CH:8][C:7]([CH:10]=[O:11])=[CH:6][C:5]2=[N:1][CH:2]=1

Participants

8

Reactant 4

HCID 24408BromineHCID 24437Sodium SulfiteHCID 517045Sodium AcetateHCID 11029972Imidazo[1,2-A]pyridine-7-carbaldehyde

Product 2

HCID 222AmmoniaHCID 768496803-Bromoimidazo[1,2-A]pyridine-7-carbaldehydeYield 113.7%

Reagents, catalysts & solvents 2

HCID 887MethanolSolventHCID 253877Potassium BromideSolvent

Procedure

Imidazo[1,2-α]pyridine-7-carboxaldehyde (0.92 g, 9.38 mmol) and sodium acetate (0.62 g, 7.52 mmol) were dissolved in a saturated solution of potassium bromide in methanol (20 ml) and cooled to 0° C. before dropwise addition of bromine (1.05 g, 6.58 mmol) over 5 min. The mixture was allowed to stir for 15 minutes before adding saturated sodium sulphite solution (1 ml). The reaction was evaporated to dryness and the residue partitioned between ethyl acetate and 10% sodium sulfate solution. The organics were washed with water, brine, dried over sodium sulfate and concentrated to give a yellow oil. This oil was purified by flash column chromatography on silica eluting with dichloromethane/methanol/conc. ammonia (gradient 99:1:0.1 through to 97:3:0.3) to give 3-bromo-imidazo[1,2-α]pyridine-7-carboxaldehyde (1.20 g, 85%) as a yellow solid. 1H NMR (360 MHz, CDCl3) δH 7.47 (1H, dd, J 7 and 1), 7.84 (1H, s), 8.12 (1H, d, J 2), 8.36 (1H, d, J 7 and 1), 10.03 (1H, s).

Workup

  1. customThe reaction was evaporated to dryness
  2. customthe residue partitioned between ethyl acetate and 10% sodium sulfate solution
  3. washThe organics were washed with water, brine
  4. dry with materialdried over sodium sulfate
  5. concentrationconcentrated
  6. customto give a yellow oil
  7. customThis oil was purified by flash column chromatography on silica eluting with dichloromethane/methanol/conc

Sources & evidence

ORD record
ord-ad170f96ec2d45e3a117a99cc7f76954
Source dataset
uspto-grants-2005_03
Patent number
US06872731B2

Reaction notes

Loading…