A new reversible 1,3-dipolar cycloaddition and its application in dynamic covalent chemistry
Abstract
In the past decades, chemists have designed and investigated artificial self-replicating molecules. A self-replicating molecule is one that can assemble its
building blocks through molecular recognition, the building blocks are brought in
close proximity and can react to form another copy of the self-replicator. Self-replicators are important to consider in the context of the origin of life, as it is
hypothesised that molecular self-replicating entities are at the basis of the emergence
of life on earth. Previously, self-replicating molecules have been reported based on
cycloaddition reactions, and in particular the Philp Laboratory worked on a self-replicating system based on the cycloaddition reaction between a maleimide and a
nitrone. The thesis presented here, however, focuses on the implementation of
another dipolarophile in a recognition-mediated reaction with a nitrone. 2-Arylidene-1,3-indandiones can react with nitrones in a 1,3-dipolar cycloaddition and these
compounds can be functionalised with a recognition site.
Initially, the reactivity of the indandiones in a 1,3-dipolar cycloaddition with a nitrone
is studied in the absence of recognition-mediated reaction pathways. The
investigation is carried out experimentally and computationally with semi-empirical
methods and Density Functional Theory. Secondly, we investigated the effect of
molecular recognition on the rate and conversion of the cycloaddition reaction.
Depending on the location of the recognition site relative to the reactive site on the
nitrone, the rate can be accelerated up to almost seven times.
Synthetic chemists, traditionally, investigate chemical reactions in isolation and one
product is purified after the chemical reaction. In biochemical systems, however, a
mixture of many compounds is present. In the final part of this thesis, the recognition-mediated reaction is described between the indandione and a mixture of nitrones and
any difference in behaviour between the reaction in isolation and the reaction in a
mixture of starting materials is investigated.
Type
Thesis, MPhil Master of Philosophy
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