To a solution of n-BuLi (26.1 mL, 52.09 mmol) in THF (70 mL, Na distilled) was added N,N-diisopropylamine (7.30 mL, 52.09 mmol) and 2,3-difluoropyridine (5.00 g, 43.41 mmol) successively at -78 C. The resulting mixture was stirred at -78C for 1 hour and then poured over crushed dry ice (excess). The reaction was allowed to warm up to room temperature for 1 h and after evaporation of the excess dry ice and THF, the residue was added to water (100 mL) and washed with EtOAc (2 x 50 mL). The aqueous layer was then acidified to pH
1 and extracted with EtOAc (2 x 100 mL). The combined organic extracts were dried and evaporated to give the product 2,3-difluoropyridine-4-carboxylic acid. Yield = 2.39 g, 35%.
