Amino acid ferrocene conjugates using sulfonamide linkages

Abstract

This report presents the synthesis and characterization of mono- and bis(amino acid ester) ferrocene complexes generated using a sulfonamide linking strategy as an alternative to the more heavily explored amide linking strategy. These compounds were investigated to test their ability to form hydrogen bonding interactions both in the solid state and in solution, and were compared to the previously observed intramolecular interstrand crosslinking seen in amide-linked ferrocene constructs. Synthesized compounds also included controls that do not exhibit sulfonamide N-H bonds and thus cannot engage in hydrogen bonding. In the solid state, we observe both S=O⋯H-N and C=O⋯H-N intermolecular interactions, but we do not observe any intramolecular interstrand hydrogen bonding. In the solution phase, we also do not see any intramolecular hydrogen bonding interactions in these compounds as measured by titration of d6-DMSO as a competitive hydrogen bonding reagent. We also collected CD spectra on these compounds, which revealed that the chiral peptides can induce dichroism in the dd transition of the ferrocene units. Our results indicate that the peptide-ferrocene linking group governs whether intermolecular hydrogen bonding interactions can occur between the amino acids adjacent to the cyclopentadienyl groups.

Highly Soluble Imidazolium Ferrocene Bis(sulfonate) Salts for Redox Flow Battery Applications

“…Bis­(ferrocene sulfonic acid) is generated via the reaction of ferrocene and chlorosulfonic acid . Our group has used this reagent in the past to make sulfonamide conjugates containing amino acids and biomolecules as well as various electrochemically active sulfonate salts. − The bis­(ferrocene sulfonic acid) was initially reacted with Ag 2 O to generate silver salts in situ with a subsequent introduction of the imidazolium halide salts to afford pure materials 1 – 6 (Scheme ). The preparation of the silver ferrocene salt was completed first to reduce the generation of silver N-heterocyclic carbenes, as they are classically prepared by reacting imidazolium salts with silver­(I) oxide. , …”

Functionalization of N,N-Dialkylferrocenesulfonamides toward Substituted Derivatives

“…Apart from medicinal applications, ferrocene sulfonamides are attractive structures for their ability to act as sensors (hydrogen bonding interactions) or monomers for polymerization . However, despite all these potential applications, polysubstituted ferrocene sulfonamides have barely been studied …”

Administration of ferrocene‐modified amino acids induces changes in synaptic transmission in the CA1 area of the hippocampus

“…Starting from ferrocenyl alcohols FcCH (OH)R and ethyl esters of glycine and β‐alanine under acidic catalysis in aqueous organic medium the corresponding products were obtained . Recently Ziegler and co‐workers elaborated new synthetic route to ferrocene complexes of such type using a sulfonamide linking strategy . Ferrocene‐based pyrazole‐containing amino acids were successfully prepared by Vukićević and co‐workers, and evaluated as promising antitumor agents .…”

“…[46] Recently Ziegler and co-workers elaborated new synthetic route to ferrocene complexes of such type using a sulfonamide linking strategy. [47,48] Ferrocenebased pyrazole-containing amino acids were successfully prepared by Vuki cevi c and co-workers, and evaluated as promising antitumor agents. [49] In a recent review, ferrocene conjugates with several natural amino acids were subjected to the detailed conformational and DFT analyses in order to determine the turn-inducing potential of ferrocene scaffolds in the corresponding peptidomimetics.…”