Triisopropyl borate → (5-(Cyclopropylcarbamoyl)-3-fluoro-2-methylphenyl)boronic acid

Participants

Reaction Conditions

Reaction Steps

N-Cyclopropyl-5-fluoro-3-iodo-4-methylbenzamide (Intermediate 63) (5 g) in tetrahydrofuran (75 ml) was cooled to 0° C. then treated with sodium hydride (60% oil dispersion, 1.23 g) portionwise over 10 minutes. Once effervescence had ceased the reaction was cooled to −75° C. and n-butyl lithium (1.6M in hexanes, 20 ml) was added over 25 min maintaining a temperature of <−70° C. Triisopropyl borate (8 ml) was added over 10 min and the mixture was stirred at −70° C. for 4 h. Water (20 ml) was added and the mixture was allowed to warm to 5° C. The solvent was removed under vacuum and the residue was partitioned between saturated aqueous ammonium chloride and ethyl acetate. The organic phase was washed with saturated aqueous ammonium chloride and brine, dried (Na2SO4) and concentrated under vacuum. The residue was dissolved in dichloromethane/ethyl acetate and purified by column chromatography on silica eluting with dichloromethane:ethyl acetate (95:5 to 0:100) then methanol to give the title compound.

Provenance & Evidence