Trifluoroacetic acid → 4-(4-Bromo-pyridin-2-yl)-4-oxo-butyraldehyde
Reaction equation
[Br:1][C:2]1[CH:7]=[CH:6][N:5]=[C:4]([C:8](=[O:16])[CH2:9][CH2:10][CH:11](OC)[O:12]C)[CH:3]=1.FC(F)(F)C(O)=O>C(Cl)Cl>[Br:1][C:2]1[CH:7]=[CH:6][N:5]=[C:4]([C:8](=[O:16])[CH2:9][CH2:10][CH:11]=[O:12])[CH:3]=1Participants
4
Reactant 2
Product 1
Reagents, catalysts & solvents 1
Procedure
To a solution of 1-(4-bromo-pyridin-2-yl)-4,4-dimethoxy-butan-1-one (2) (crude from Step 2, 11 g, 38.2 mmol) in 100 of CH2Cl2 at room temperature is added trifluoroacetic acid (10.9 g, 95.4 mmol) and the reaction mixture is stirred overnight. The reaction is concentrated, the residue dissolved in ethyl acetate (150 mL) and washed with water 3 times. The organic layers are combined, dried over Na2SO4 and the solvent evaporated. The residue is purified by flash column chromatography (30% EtOAc in hexanes) to give 4-(4-bromo-pyridin-2-yl)-4-oxo-butyraldehyde (3) as an yellow oil. (4.16 g, 45%): MS ES+244.04.