In a sealed tube, a mixture of 5-bromo-2-chloro-3-fluoropyridine 205-1 (631 mg, 3 mmol), 0.5 M (2-tert-butoxy-2-oxoethyl) zinc(II) chloride 205-2 in ether (6.6 mL, 3.3 mmol), Pd(dba)2 (87 mg, 0.15 mmol), 1,2,3,4,5-pentaphenyl-1′-(di-t-butylphosphino)ferrocene (Q-phos, 107 mg, 0.15 mmol), and THF (12 mL) under argon was stirred at 70° C. for 18 hours. After cooled to room temperature, the solvents were evaporated and the residue was redissolved in ethyl acetate, washed with water and brine, dried over Na2SO4 and concentrated to dryness by rotary evaporation. The crude product was purified by silica gel flash chromatography, eluted with 30% ethyl acetate in hexane to give tert-butyl 2-(6-chloro-5-fluoropyridin-3-yl)acetate 205-3 as a brown oil. MS m/z 246.1 (M+1).
