18F-labelling of nitrogen-containing arenes via copper-mediated radiofluorination (CMRF) was investigated. The studies targeted the analogues of the anti-cancer drug melflufen with an alkylating bis(2-chloroethyl)amino pharmacophore. Studies of the melflufen analogues and various model compounds indicated that the copper mediated boron-fluorine-18 exchange reaction is affected differently by the three nitrogen-containing groups in the target compound. The largest inhibitory effects on the fluorine labelling process were exerted by the tertiary amine based bis(2-chloroethyl)amino pharmacophore. The best results were achieved by applying bipyridyl ligands for the copper mediator.