A solution of 5.1 g (34 mmol) of succinic acid monomethyl ester monochloride in 20 ml of ethyl acetate is added dropwise, while cooling with ice, to a solution of 6.0 g (22.7 mmol) of N-butyl-N-(2'-cyanobiphenyl-4-ylmethyl)-amine and 13 ml of Hunig base in 100 ml of ethyl acetate. The reaction mixture is stirred at from 0° to 5° for 1 hour and then 30 ml of water are added. The organic phase is washed in succession with 30 ml of 2N hydrochloric acid, water and saturated potassium hydrogen carbonate solution and is dried. Evaporation of the solvent yields crude 3-methoxycarbonylpropanoic acid N-butyl-N-(2'-cyanobiphenyl-4-ylmethyl)-amide in the form of an oil that has an Rf value of 0.32 [toluene/methanol (19:1)].
