2-(4-Trifluoromethoxy-phenyl)-2,8-diaza-spiro[4.5]decane-1,7-dione (0.105 g), product of example 1 step D), was dissolved in dry THF (10 ml), cooled to −78° C. under an argon atmosphere, treated dropwise with n-butyllithium (1.6 molar solution in hexanes, 0.22 ml) and then stirred for 20 minutes at −78° C. 2-Chlorobenzenesulfonyl chloride (0.074 g) in THF (2 ml) was then added dropwise, the mixture was stirred 15 minutes at −78° C., the cooling bath was removed and stirring was continued for further 75 minutes, allowing the temperature of the reaction mixture to rise to RT. The reaction mixture was then concentrated in vacuo, the residue adsorbed on silica gel and chromatographed on silica gel (AcOEt/heptane, gradient from 0 to 30%) to give the desired product (0.051 g) as an off-white solid. MS (ESI): 503.0 (MH−).
