To a solution of 6-(hydroxymethyl)-2-pyridinecarboxylic acid (500 mg, 3.27 mmol) in chloroform (10 ml) and N,N-dimethylformamide (DMF) (0.1 ml) was added thionyl chloride (1 ml, 13.70 mmol) and the mixture heated at 65° C. for 1 hr. Solvent was removed in vacuo and the residue was azeotroped with chloroform (5 ml) then dried on a high vacuum line for 30 mins to afford an orange oil (650 mg), presumed to be 6-(chloromethyl)-2-pyridinecarbonyl chloride. To solution of 1-(phenylsulfonyl)-6-(1H-pyrrolo[2,3-b]pyridin-4-yl)-1H-indazol-4-amine (1.63 g, 4.19 mmol) in chloroform (25 ml) at 0° C. was added DIPEA (1.462 ml, 8.37 mmol). 6-(chloromethyl)-2-pyridinecarbonyl chloride (1.193 g, 6.28 mmol) in Chloroform (20 ml) was then added dropwise and the mixture was stirred at 0° C. for 15 min. A further portion of 6-(chloromethyl)-2-pyridinecarbonyl chloride (1.193 g, 6.28 mmol) in chloroform (20 ml) was added and the mixture was stirred at 0° C. for 15 min then warmed to room temperature and stirred for 18 h. The reaction mixture was quenched with water (100 ml) and extracted with DCM (100 ml). The solvent was removed in vacuo to give an orange solid. Trituration with DCM afforded the title compound (370 mg). The filtrate from the trituration was concentrated in vacuo to ˜5 ml volume and then added to the top of 2×100 g silica SPE cartridges. The cartridges were eluted with a gradient of 0-100% EtOAc/DCM over 60 mins on the Flash Master II. The product-containing fractions were combined and the solvent removed in vacuo to give a further portion of the title compound as an off-white solid (530 mg).
