The use of crown ethers in peptide chemistry. Part 1. Syntheses of amino acid complexes with the cyclic polyether 18-crown-6 and their oligomerisation in dicyclohexylcarbodi-imide-containing solutions

Abstract

The synthesis of amino acid complexes with the cyclic polyether 18-crown-6 and their solubility properties in organic solvents are described. Oligo homo-amino acid peptides have been prepared using the crown ether complexes and dicyclohexylcarbodi-imide as coupling agent. The mechanism leading to the formation of the oligopeptides has been discussed and proved to involve the transferring of one N-H proton from the crown ether complex to the carbodi-imide nitrogen.