Diethyl azodicarboxylate (0.235 ml, 1.49 mmol) was added at 0°C. to a stirred solution of triphenylphosphine (0.392 g, 1.49 mmol) and 2-fluoren-9-ylidene-ethanol (0.208 g, 1.0 mmol) in dry THF (5 ml) and the mixture stirred for 5 min. A solution of ethyl 2-ethoxy-3-(4-hydroxy-phenyl)-propionate (0.356 g, 1.49 mmol) in dry THF (5 ml) was then added, the mixture allowed to warm to room temperature, and stirring continued for 72 h. The resulting mixture was treated with water (50 ml), and the products extracted into dichloromethane (3×20 ml). The extracts were combined, washed with brine, dried (Na2SO4) and evaporated to a yellow gum. This was then purified by column chromatography on silica gel (15% Et2O in petroleum eluent) to give ethyl 2-ethoxy-3-[4-(2-fluoren-9-ylidene-ethoxy)-phenyl]-propionate as a yellow gum; 0.28 g (60%).
