The starting material can be prepared, for example, as follows: A solution of 3.3 g (17 mmol) of 4-methoxycarbonyl-4-methyl-pentanoic acid chloride in 20 ml of ethyl acetate is added dropwise at from 0° to 5° to a solution of 3.0 g (11.3 mmol) of N-butyl-N-(2'-cyanobiphenyl-4-ylmethyl)-amine and 6.5 ml of Hunig base in 50 ml of ethyl acetate. The reaction mixture is stirred for 1 hour and then worked up analogously to Example 1 b) to yield 4-methoxycarbonyl-4-methyl-pentanoic acid N-butyl-N-(2'-cyano-biphenyl-4-ylmethyl)-amide in the form of an oil that has an Rf value of 0.27 [toluene/methanol (19:1)] and is further used in crude form.
