Dimethyl Sulfoxide → 5-fluoro-2-methyl-2H-indazole-4-carbaldehyde

Participants

Reaction Steps

To a solution of dimethyl sulfoxide (7.56 mL, 107 mmol) in dichloromethane (100 mL) was added oxalyl chloride (4.86 mL, 53.3 mmol) at −78° C., and the mixture was stirred for 30 min. To the reaction mixture was added a solution of (5-fluoro-2-methyl-2H-indazol-4-yl)methanol (3.20 g, 17.8 mmol) in dichloromethane (78.0 mL), and the mixture was stirred for 2 hr. To the reaction mixture was added triethylamine (22.5 mL, 160 mmol) at −78° C., and the mixture was stirred for 1 hr. The reaction mixture was concentrated under reduced pressure, and the residue was purified by flash silica gel column chromatography (ethyl acetate/hexane=1/3) to give the title compound (3.00 g, yield 95%).

Provenance & Evidence