A stirred solution of methyl benzoylamino(dimethoxyphosphoryl)acetate (4.25 g) in dry tetrahydrofuran (30 mL) is treated with sodium hydride (0.66 g, 60% dispersion in mineral oil) under nitrogen. After stirring for 15 minutes a solution of 2,4-dibenzyloxybenzaldehyde (4.74 g) in dry tetrahydrofuran (15 mL) is added dropwise. The reaction mixture is stirred at room temperature for 18 hours, evaporated and the residue partitioned between ethyl acetate (100 mL) and water (75 mL). The organic phase is washed with brine (50 mL), dried over magnesium sulphate and evaporated. The residual yellow oil is purified by flash chromatography on silica eluting with initially with dichloro-methane then with a mixture of dichloromethane and ethyl acetate (9:1 v/v). Fractions homogeneous in the required products are evaporated to give methyl (E)-2-benzoylamino-3-(2,4-dibenzyloxyphenyl)acrylate (1 g) as a yellow foam, and methyl (Z)-2-benzoylamino-3-(2,4-dibenzyloxyphenyl)-acrylate (1.6 g) as a yellow oil.
