Thesis-Final 03 June 2011 pdf - Jacobs University

Abstract
The chlorogenic acids are a family of esters formed between certain trans-cinnamic
acids and quinic acid. Chlorogenic acids are among the most abundant polyphenols,
which are naturally occurring in plants, with various biological activities beneficial to
human health. Chlorogenic acids are secondary metabolites that are found in plants.
As a group they generally contain several subgroups and usually several isomers
within each subgroup. The development of methods for the synthesis of existing
chlorogenic acids and new series of chlorogenic acids were developed in this thesis in
order to have the compounds available as analytical standards, for confirmation of
previous and future LC/MS work, and most importantly for individual biological
testing in various assays.
The target compounds were obtained with two strategies 1.selective synthesis using
appropriate protecting groups strategies, 2.nonnselective synthesis producing mixtures
of isomers. The general strategy, which was applied through out the thesis in order to
synthesise the target compounds was, as follows;
• Preperation of acid chlorides of cinnamic acids
• Preparation of protected quinic acid derivatives
• Acylation
• Deprotection
A series of mono-acyl chlorogenic acids and esters, in particular of those substituted
in the 1-, 3-, 4- and 5- positions of the quinic acid with coumaroyl, feruloyl, caffeoyl
and dimethoxy cinnamoyl and cinnamoyl substituents, have been successfully
synthesised. As intermediates in these syntheses a series of quinide esters, potential
metabolites and degradation products of naturally occurring chlorogenic acids have
also been obtained. The first examples of di-acyl chlorogenic acids, have been
successfully synthesised. A general protection and deprotection strategy for the
synthesis of chlorogenic acids has been established. Poly-acyl chlorogenic acids
starting from qunic acid and quinic acid lactones also have been established. The right
conditions for the synthesis of certain type of chlorogenic acids and esters have been
established in this work.
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