Synthesis of useful aromatic derivatives of bile acids through Click chemistry

Bile acids are a very important class of natural surfactants, showing themselves and their derivatives as effective self-assembling materials. The morphology of bile acid derivative aggregates is strongly dependant upon the substituents present both on the rigid steroid backbone and on the side chain, making them suitable for applications in nanochemistry, sensing and drug delivery. In the last years our group has been involved in a project concerning the preparation of bile acid derivatives, bearing aromatic subunits on the C-3 of the steroid polycyclic ring. The Cu-promoted cycloaddition (click reaction) of azides to aromatic alkynes was used as the key-step in the synthesis of such derivatives, allowing us to synthesize several different systems, just like salicylaldehyde, precursors of salophene complexes, able to give self-assembly. The click chemistry approach was also useful to link the steroid backbone to other kinds of aromatic subunits, such as ferrocene, allowing us to obtain compounds, able to chemically modify the surface of carbon electrodes for sensing applications.