Efficient methods for the construction of ferrocenyl-ammonium salt systems have received
considerable attention as these ubiquitous structural motifs have been found in ionic liquids as
well as bioactive products and the 1-(aminomethyl)ferrocene synthon has become a valuable
architectural platform for the development of new synthetic methodologies.
Quaternary ammonium ion can be readily prepared by the aminomethylation of ferrocene 1,
followed by the methylation of the resulting tertiary amine. However the ferrocene 1 and many
of its derivatives are easily oxidized by air in the presence of acids and quit difficult to prepare
the corresponding chloride by simple treatment with thionyl chloride or hydrogen chloride. Since
the ferrocene nucleus has been observed to possess certain aromatic properties, the
corresponding quaternary ammonium ion in the ferrocene series might be expected to exhibit
Hofmann type of elimination to form tertiary amine.

In this communication, we demonstrate that selective formation of N,Ndimethylaminomethylferrocene
HCl 3 can be achieved using a simple mixing at room
temperature of equal amount of the ethyl 3-chloropropanoate or 3-chloropropanenitrile (both has
a β-hydrogen) with N,N-dimethylaminomethylferrocene 2 in AcCN solution. Structure of target
compound has been confirmed by X-Ray.
We thank the bilateral BMBF project (01DK13029) for financial support.