Towards peptide isostere libraries: aqueous aldol reactions on hydrophilic solid supports

Abstract

Polar polyoxyethylene-polyoxypropylene (POEPOP) resin was derivatised with a 4-hydroxymethyl phenoxy linker and used as a solid support for lanthanide triflate catalysed Mukaiyama type solid phase aldol reactions. The conditions were optimised using resin bound 4-alkoxybenzaldehyde and it was shown that use of an aqueous solvent was crucial. Also, the reactions were performed with an N-terminal peptide aldehyde substrate in very high yields. POEPOP resins prepared with different monomer chain lengths and commercially available PEG-grafted NovaSyn TG resin were compared in the reactions.