1: Ethyl (cis/trans)-4-lt;(tert-butyldimethylsilyl)oxygt;cyclohexanecarboxylate With lithium diisopropyl amide in tetrahydrofuran; n-heptane; ethylbenzene T=-78°C; 0.5 h; 2: 1-bromo-2-chloro-ethane in tetrahydrofuran; n-heptane; ethylbenzene T=-78 - 20°C; 3 h;

water; silver nitrate in 1,4-dioxane 0.5 h; Heating / reflux;