NBS (29.0 mg, 0.163 mmol) was added to a stirring solution of 4-chloro-3-(2-(4-fluorophenyl)furo[2,3-b]pyridin-5-yl)benzoic acid (50 mg, 0.136 mmol) in THF (4.5 mL) at room temperature. It was allowed to stir for 1 hour. An additional portion of NBS (29 mg, 0.16 mmol) was added it was allowed to stir for 1 hour after which another portion of NBS (29 mg, 0.16 mmol) was added and the reaction was allowed to stir overnight. The mixture was diluted with EtOAc and washed with 10% NaHSO3, and sat NaCl. The organic phase was dried over Na2SO4, filtered and concentrated and triturated with DCM to give the expected product 3-(3-bromo-2-(4-fluorophenyl)furo[2,3-b]pyridin-5-yl)-4-chlorobenzoic acid (57 mg, 0.128 mmol, 94% yield) consistent by LCMS and NMR. 1H NMR (500 MHz, DMSO-d6) δ ppm 8.48 (1H, d, J=2.14 Hz), 8.19-8.24 (2H, m), 8.17 (1H, d, J=2.14 Hz), 7.99-8.05 (2H, m), 7.79 (1H, d, J=8.24 Hz), 7.46-7.52 (2H, m). LC-MS retention time: 1.29 min; m/z (MH+): 447. LC data was recorded on a Shimadzu LC-10AS liquid chromatograph equipped with a Waters XBridge 5 u C18 4.6×50 mm column using a SPD-10AV UV-Vis detector at a detector wave length of 220 nM. The elution conditions employed a flow rate of 5 ml/min, a gradient of 100% solvent A/0% solvent B to 0% solvent A/100% solvent B, a gradient time of 2 min, a hold time of 1 min, and an analysis time of 3 min where solvent A was 5% acetonitrile/95% H2O/10 mM ammonium acetate and solvent B was 5% H2O/95% acetonitrile/10 mM ammonium acetate. MS data was determined using a Micromass Platform for LC in electrospray mode.
