Structure-activity relationships in mutagenicity and in nucleophilic ring opening of N-(arylmethyl)phenanthrene 9,10-imines

Ten derivatives of N-benzylphenanthrene 9,10-imine with different substituents on the phenyl ring were synthesized and subjected to mutagenicity tests in Salmonella typhimurium TA100. While electron donating groups were found to enhance the biological activity, electron attracting and bulky substituents lowered the mutagenic potency. A similar dependence on the electronic structure was observed in triethylamine/acetonitrile-promoted interaction of the title imines and 4-nitrothiophenol. This similarity suggests that both biochemical and chemical processes involve mechanisms in which protonation of the aziridine nitrogen is rate controlling, and the attack of the cellular or model nucleophile is a fast step. In contrast to these processes, the reaction of the imines with 4-nitrothiophenol in the presence of 1,5-diazabicyclo[4.3.0] non-5-ene proved to proceed by an SN2 mechanism and to be enhanced by electron attracting substituents.