Dimethyl Sulfoxide → 4-(5-Ethoxy-2-fluoro-phenyl)-3,6-dimethyl-pyridine-2-carbaldehyde

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Reaction Steps

To a solution of oxalyl chloride (1.46 mL, 17.3 mmol) in DCM (50 mL) cooled to −78° C. was added dropwise, a solution of dimethyl sulfoxide (2.68 mL, 37.74 mmol) in DCM (5 mL). After addition, the solution was stirred for 15 mins. A solution of [4-(5-ethoxy-2-fluoro-phenyl)-3,6-dimethyl-2-pyridyl]methanol (which may be prepared as described in Description 140) (4.33 g, 15.73 mmol) in DCM (10 mL) was then added dropwise over about 5 mins. The mixture was allowed to stir at −78° C. for 2 hrs. Triethylamine (8.74 mL, 62.91 mmol) was added dropwise giving a precipitate and this was allowed to warm to room temperature over one hour. The reaction mixture was washed with water and brine, dried over magnesium sulphate and evaporated. The crude residue was purified by silica gel chromatography (50 g SiO2) eluting with ethyl acetate in iso-hexane (0-40%). Evaporation of desired fractions gave 4-(5-ethoxy-2-fluoro-phenyl)-3,6-dimethyl-pyridine-2-carbaldehyde (D141) (2.89 g, 10.574 mmol, 67.2% yield) as a yellow solid;

Provenance & Evidence