A protocol for parallel solid-phase synthesis of Ï-amino acid-elongated philanthotoxins was developed for exploration of structure-activity relationships for unnatural wasp toxin analogues. Several methods for on-resin activation of N-trityl-linked Ï-amino acids were investigated, and the influence of chain length upon activation as pentafluorophenyl (Pfp) esters was examined. Comparison of Pfp-ester activation with phosphonium- and aminium/uronium-promoted coupling without pre-activation of the resin-bound carboxylic acids showed that only benzotriazol-1-yloxytris(pyrrolidino)phosphonium hexafluorophosphate (PyBOP) exhibited a comparable efficiency. The present Pfp ester protocol gave high yields and purities of the resulting philanthotoxin analogues; however, in the case of γ-aminobutyric acid (GABA), use of PyBOP was required in order to avoid lactamization to 2-pyrrolidone.
Solid-phase synthesis of neuroactive spider–wasp hybrid toxin analogues using a backbone amide linker
作者:Christian A. Olsen、Matthias Witt、Henrik Franzyk、Jerzy W. Jaroszewski
DOI:10.1016/j.tetlet.2006.11.074
日期:2007.1
Polyamine toxins isolated from the venoms of spiders and wasps and their synthetic analogues are uncompetitive antagonists of ligand-gated ionotropic receptors in the central- and peripheral nervous systems, and have proved valuable as tools for the investigation of receptor structure and function. In the present letter we describe the efficient solid-phase synthesis (SPS) of novel hybrid toxins using