Methodological studies in solid phase synthesis : Linkers and applications of multi-component condensations

Solid phase synthesis has become an increasingly important tool in the synthesis of oligopolymers and small organic molecules. This thesis covers three important areas in the solid phase synthesis technique: linker strategies, reduction methods and novel routes to complex heterocycles. The synthesis of the OMPPA [4-(3-hydroxy-4-metylpentyl)phenyl acetic acid] linker is described. This linker is compatible with the Boc/Bzl protective group strategy, and yields peptide acids upon cleavage from solid support. The OMPPA linker is stable towards “low-acid” treatment and is self-scavenging during final cleavage of the peptide product from solid support. These properties are beneficial for peptide purity and yields. The synthesis of the HMPPA [3-(4-hydroxymethylphenylsulfanyl)propanoic acid] linker is described. This safety catch linker is compatible with both Fmoc/tBu- and Boc/Bzl protective group strategies in solid phase peptide synthesis. The HMPPA linker is stable towards super acids yet final cleavage from solid support is performed by a relatively mild reductive acidolysis method, yielding peptide acids. It is suggested that this linker may be useful when synthesizing cyclic peptides on solid support. A new facile method for reducing cystine moieties is described. Adding metallic zinc to cystine containing peptides and proteins dissolved in slightly acidic aqueous and/or non-aqueous solutions, results in rapid disulfide reduction. This method is compatible with functional groups commonly present in peptides and proteins. The solid phase synthesis of oxygen-bridged tetrahydropyridones via a multi-component condensation reaction is described. Expected products were obtained in reasonable yields using both aromatic- and aliphatic ketones. This class of compounds has the general physico-chemical properties that are typical for drugs with high pharmacological activity.