4,4'-Dihydroxybenzophenone (I) is condensed with 1,4-dibromobutane (II) by means of KH in THF/DMF to afford monoalkylated compound (III), which is then subjected to a McMurry cross-coupling reaction with the organometallic compound (IV) in refluxing THF in the presence of TiCl4 and Zn to provide the isomeric mixture (V). Finally, bromo compound (V) is converted into the target product by first heating with dimethylamine (HNMe2) in MeOH followed by isomer separation by means of preparative HPLC chromatography.