876 mg of ethyl 3-(3-bromo-5-[(tertiary butoxycarbonyl)amino]methyl-4-methoxyphenyl)-2-isopropoxypropionate was dissolved in 5 ml propionitrile, and 182 mg of sodium cyanide, 214 mg of tetrakistriphenylphosphine palladium and 70 mg of copper iodide were added, followed by heating under reflux overnight in a nitrogen atmosphere. The reaction mixture was cooled to room temperature, ethyl acetate was added thereto and filtered through Celite. The filtrate was evapoarated and the residue was purified by silica gel column chromatography, and from fractions eluted with hexane-ethyl acetate (4:1), 586 mg of ethyl 3-(3-cyano-5-[(tertiary butoxycarbonyl)amino]methyl-4-methoxyphenyl)-2-isopropoxypropionate was obtained.
