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

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Reaction Steps

A solution of 0.109 g (0.40 mmol) 2,2-dimethyl-5-(4-trifluoromethoxy-phenyl)-pent-4-yn-1-ol (example 24E]) in 0.4 ml CH2Cl2 was treated at 0° C. with 0.11 ml (0.48 mmol) 2,6-di-tert-butylpyridine and 0.07 ml (0.44 mmol) trifluoromethanesulfonic anhydride. After 1.5 h at 0° C. the solution was evaporated, dissolved in 1.5 ml acetonitrile and added to a suspension of 0.142 g (0.48 mmol) of 2-(4-acetylsulfanyl-2-methyl-phenoxy)-2-methyl-propionic acid ethyl ester (example 1C]) and 0.274 g (0.84 mmol) of Cs2CO3 in 2.5 ml of acetonitrile and 0.1 ml of MeOH. After vigorous stirring for 20 h at ambient temperature and filtration, the solvent was evaporated and the residue re-dissolved in dichloromethane and filtered again and evaporated. Purification by flash chromatography (SiO2, n-heptane/EtOAc 2.5%) yielded 0.18 g of the title compound as colorless viscous oil.

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