The above benzonitrile (4.89 g, 26 mmol) was dissolved in methyl ethyl ketone (100 ml), and potassium carbonate (21.7 g, 157 mmol), potassium iodide (3.45 g, 52 mmol), and 5-(3-bromo-1-propylidene)-10,11-dihydro-5H-dibenzo[a,d]cycloheptene (8.18 g, 26 mmol), were added. The resulting mixture was stirred at reflux temperature for 18 h. After cooling to room temperature, ethyl acetate (200 ml) was added and the mixture was washed with water (2×150 ml), dried (MgSO4) and concentrated in vacuo. The residue was purified by flash chromatography on silica gel eluting first with a mixture of ethyl acetate and heptane (1:4), and then with a mixture of ethyl acetate and heptane (1:2). This afforded 5.60 g of the title compound as a solid.
