Synthesis, conformational analysis and application of tropane-based Fmoc-amino acid derivatives: novel antagonists of fibrinogen receptor, GPIIb/IIIa

As the gap is bridged between peptide and non-peptide drugs, molecular scaffolds are gaining prominence as a means to restrict and mimic peptide conformation. In this respect, non-peptide natural products, particularly those of medicinal value are providing a significant resource in the design of novel peptidomimetics. [1] The tropane alkaloids including cocaine, anatoxin-a and epibatidine, offer templates well suited to peptidomimetic application. The semi-rigid structure, diverse side-chain functionality and stereochemistry, established synthetic chemistry and applicability to solid phase synthesis are all desirable properties of such templates, and we have recently reported the synthesis of a range of tropane amino acids [2,3]. In order to demonstrate the utility of tropane amino acids we have incorporated them as glycine replacements into the ‘native’ GPIIb/IIIa inhibitor Arg– Gly–Asp–Ser (RGDS) [4] to establish if activity could be retained and equally as importantly to establish if useful structure function data could be gathered to expedite the generation of pharmacophores.