A solution of 1.75 g (3 mmol) of ethyl (Z)-2-ethoxy-3-{3′-[methyl-(4-nitrophenoxycarbonyl)amino]biphenyl-4-yl}acrylate and 0.4 mL (3.7 mmol) of n-butylamine in 20 mL of dimethylformamide is heated at 80° C. for 2 hours. After addition of water, the reaction medium is extracted with ethyl acetate, washed with water, dried over magnesium sulfate, filtered and evaporated. The residue obtained is purified by chromatography on a column of silica eluted with a 70/30 heptane/ethyl acetate mixture. 0.8 g (63%) of ethyl (Z)-3-[3′-(3-butyl-1-methylureido)biphenyl-4-yl]-2-ethoxyacrylate is obtained in the form of a white solid after trituration from pentane.
