Dimethylformamide → Methyl 6-chloro-2-fluoro-3-formylbenzoate

Participants

Reaction Conditions

Reaction Steps

An oven-dried round bottom flask successively purged and evacuated with N2 was charged with anhydrous THF (13.3 ml), and diisopropyl amine (6.6 ml, 46 mmol). The mixture was placed in a −78° C. dry ice/acetone bath before n-butyllithium (2.5 M in hexanes) (17 ml, 43 mmol) was added. The LDA solution was then placed in a 0° C. bath for 10 minutes before recooling to −78° C. Then, a solution of methyl 2-chloro-6-fluorobenzoate (3.50 g, 19 mmol) in THF (56 ml) was added dropwise over 30 minutes. The resulting mixture was stirred at −78° C. for 2.5 hrs, warmed to −50° C. over 30 min, and stirred for 30 minutes at −50° C. The mixture was then recooled to −78° C. before adding anhydrous dimethylformamide (14 ml, 186 mmol). The resulting mixture was stirred for 30 minutes at −78° C. and then gradually warmed to RT over 1 h. The reaction was quenched with 10% aqueous acetic acid, diluted with EtOAc and the layers were separated. The aqueous layer was extracted three times with EtOAc. The combined organics were washed with water, brine, and dried over Na2SO4, filtered and concentrated to a yellow oil, which was purified by chromatography using 12:1 hexanes/EtOAc to give the title compound as a light yellow oil, which solidified upon exposure to reduced pressure.

Provenance & Evidence