Under an argon atmosphere 7.1 mL (51.5 mmol) triethylamine are added to a solution of 16.0 g (42.9 mmol) 2-{5-[5-(4-chloro-phenyl)-pyridin-2-ylethynyl]-indol-1-yl}-ethanol in 480 mL THF and 30 mL pyridine and this is cooled to 0° C. Then a solution of 4 mL (51.5 mmol) methanesulphonic acid chloride in 20 mL THF is slowly added dropwise, the mixture is allowed to warm up to RT and stirred for a further 2 h at RT. The reaction solution is filtered and evaporated down i.vac. The residue is combined with 1 L DCM, washed with 400 mL water and the organic phase is dried over Na2SO4. After the desiccant and solvent have been eliminated the residue is suspended with 600 mL PE/DCM (5:1), suction filtered and finally dried in the air until a constant weight is obtained.
