Cesium carbonate → 2-{4-[2,2-Dimethyl-5-(4-trifluoromethoxy-phenyl)-pent-4-ynyloxy]-2-methyl-phenoxy}-2-methyl-propionic acid ethyl ester

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Reaction Steps

A solution of 0.082 g (0.30 mmol) 2,2-dimethyl-5-(4-trifluoromethoxy-phenyl)-pent-4-yn-1-ol (example 24E]) in 0.3 ml CH2Cl2 was treated at 0° C. with 0.08 ml (0.36 mmol) 2,6-di-tert-butylpyridine and 0.05 ml (0.33 mmol) trifluoromethanesulfonic anhydride. After 2.5 h at 0° C. and 0.5 h at room temperature the solution was evaporated, dissolved in 1 ml acetonitrile and added to a solution of 0.071 g (0.30 mmol) 2-(4-hydroxy-2-methyl-phenoxy)-2-methyl-propionic acid ethyl ester (described in WO 02/092590) and 0.205 g (0.63 mmol) Cs2CO3 in 2 ml acetonitrile. The mixture was stirred for 20 h at room temperature and 1 h at reflux temperature. After filtration, the residue was dissolved in dichloromethane, dried (Na2SO4), filtered and evaporated. Purification by flash chromatography (SiO2, n-heptane/EtOAc 2%) yielded 0.096 g of the title compound as light yellow oil.

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