71.2 g of 4-methoxycarbonylbenzyltriphenylphosphonium bromide and 23 g (0.15 M) of 3-nitrobenzaldehyde are added to 360 ml of acetonitrile in a 1000 ml reactor. 19 ml (0.15 M) of 1,5-diazobicyclo[4.3.0]non-5-ene (DBN) are then added and the reaction medium is then refluxed with stirring for 1 hour. The solvent is then evaporated off and the residue obtained is then purified by chromatography on silica, using dichloromethane as eluent. After evaporation, 41.6 g of a white solid are obtained (yield: 95%).
