[CH3:1][O:2][C:3](=[O:17])[C:4]([CH3:16])([CH3:15])[CH:5](O)[C:6]1[CH:11]=[C:10]([O:12][CH3:13])[CH:9]=[CH:8][N:7]=1.CCN(C(C)C)C(C)C.FC(F)(F)S(OS(C(F)(F)F)(=O)=O)(=O)=O.[I-].[Na+]>CN(C)C1C=CN=CC=1.ClCCl.[Zn]>[CH3:1][O:2][C:3](=[O:17])[C:4]([CH3:15])([CH3:16])[CH2:5][C:6]1[CH:11]=[C:10]([O:12][CH3:13])[CH:9]=[CH:8][N:7]=1
3.0 g of 3-hydroxy-3-(4-methoxypyridin-2-yl)-2,2-dimethyl-propionic acid methyl ester (compound C3), 0.153 g of 4-dimethylaminopyridine and 2.58 ml of N,N′-diisopropylethylamine are dissolved in 80 ml of dichloromethane. Trifluoromethanesulfonic acid anhydride is added dropwise under ice-cooling. The cooling bath is removed and the mixture is stirred at room temperature for 2.5 h. After evaporation in vacuo, the remaining residue is dissolved as obtained in 100 ml of 1,2-dimethoxyethane. 9.37 g of sodium iodide and 16.3 g of activated zinc are added and the mixture is stirred at 100° C. for 1.5 h. The solids are filtered off, the filtrate is diluted with 800 ml of dichloromethane and extracted several times with halfsaturated aqueous sodium chloride solution. The organic layer is dried using sodium sulfate and concentrated. The residue is purified by chromatography on silica gel (toluene/ethyl acetate 2:1) to afford 1.6 g of the title compound as an oil. MS: 224.2 (MH+). TLC: Rf=0.26 (toluene/acetone 2:1).
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