N-Allyl-N-ferrocenylmethylamines and ansa-Ferrocenylmethylamines: Synthesis, Structure, and Biological Evaluation

Reductive aminations of ferrocenecarboxaldehyde, ansa-ferrocenecarboxaldehyde, and 1,1 '-ferrocene-dicarboxaldehyde with allylamine, N-allylmethylamine, or N-allylaniline were investigated. In the case of the dialdehyde only one formyl group effectively reacted with N-allylmethylamine or N-allylaniline, thus providing a simple route to aminomethyl aldehydes and aminomethyl alcohol. 2-Aza-ansa[3] ferrocene was also obtained by reacting the dialdehyde with one equivalent of allylamine and subsequent deprotection of the nitrogen atom. The isolated N-allyl ferrocene derivatives were completely characterized by spectroscopic techniques, whereas crystal structures of four representative compounds were determined using single-crystal X-ray diffraction. MTT assays showed that these simple N-allyl ferrocene derivatives display anticancer activity (MCF-7, A-549 and PC-3 cell lines) in the micromolar range.