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.