2(R,S)-Cyanomethyl-3-α-naphthylpropionic acid: 3.0 g of α-naphthylmethylmalonic acid diethyl ester and, after 30 minutes, 0.6 ml of chloroacetonitrile are added to a stirred suspension of 0.44 g of sodium hydride dispersion in 50 ml of DMF. The reaction mixture is stirred for 1 hour at 50° and then concentrated by evaporation in a high vacuum. The residue is dissolved in ethyl acetate, washed with 0.1N hydrochloric acid and water, dried over sodium sulphate, concentrated by evaporation and purified by chromatography on silica gel with toluene, yielding cyanomethyl-(α-naphthylmethyl)-malonic acid diethyl ester.
