Title:
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Catalytic Redox Neutral Cascade Alkylations with Alcohols
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This thesis is divided into three main parts: Introduction, Results and Discussion and
Experimental.
The introduction (Chapter 1) reviews transition metal catalysed 'Redox Neutral'
Hydrogen Autotransfer Processes where both the hydrogen donor and the hydrogen
acceptor are incorporated into the final or target molecule, e.g. utilisation of alcohols as
e1ectrophiles III C-N and C-C bond form~tions. The review also gives a brief
introduction to the Meerwin-Ponndorf-Verley (MPV)-reduction and the reverse
Oppenauer oxidation together with their modern transition metal catalysed versions and
their mechanisms.
The Results and Discussion section details the author's own work -and is divided into
four Chapters: Chapter 2 describes the development of a highly efficient iridium
catalysed selective monoalkylation cascade of arylacetonitriles with primary alcohols to
afford a-alkylated nitriles in 67-93% yield. It was further demonstrated that such
processes can'be achieved by conventional or microwave heating and that bis- and trisprimary
alcohols are also processed efficiently. The mechanism was studied using
deuterium labelled substrates and mechanism proposed.
Chapter 3 describes the investigation of other activated methylene pronucleophiles
such as 1.3-dimethylbarbituric acid which successfully undergoes selective mono C5alkylation
with a variety ofalcohols under both conventional and microwave heating.
Chapter 4 describes investigations into an uimsual C5-autoxidation process of the C5-
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monoalkylated barbiturates and its development into a novel iridium catalysed
sequential one-pot C5-alkylation f.hydroxylation cascade of 1,3-dimethylbarbituric acid
and alcohols giving the corresponding tertiary alcohols in 49-83% yield. The oxidation
process is believed to involve singlet oxygen and shows interesting additive effects.
Chapter 5. describes the successful extension 'of the iridium catalysed alkylation
cascade into a novel bimetallic sequential one-pot Ir(III) / Pd(O) catalysed process which
gives easy access to compounds of high molecular complexity from simple starting
materials. This highly atom economic cascade involves the formation of three new C-C
bonds, one tetrasubstituted carbon centre, one spirocyclic ring and one di- or trisubstituted
exocyclic alkene regio- and stereoselectively.
Chapter 6 (Experimental) contains full experimental details of the author's own work,
together with appropriate physical, spectroscopic and analytical data for all new,
compounds.
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