440 mg (1.5 mmol) 5-[1-(4-Fluoro-phenyl)-1H-indol-5-yl]-pent-4-yn-1-ol in 15 ml CH2Cl2 were treated with 0.15 ml (1.8 mmol) methane sulfonyl chloride and 0.63 ml (4.5 mmol) triethyl amine at 0° C. for 10 min. The solution was stirred at RT for 2 h and was diluted with CH2Cl2. The organic phase was extracted with 1M HCl and water, and dried over Na2SO4. Evaporation yielded 400 mg (71%) Methanesulfonic acid 5-[1-(4-fluoro-phenyl)-1H-indol-5-yl]-pent-4-ynyl ester as light yellow viscous oil, MS: 372 (MH+).
