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Title: Reactions of allenylpalladium intermediates in organic synthesis
Author: Daniels, David S. B.
ISNI:       0000 0004 2746 1675
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2013
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This thesis describes our examination of the reactivity of allenylpalladium intermediates generated from the reaction of palladium(0) with propargylic electrophiles. Chapter 1 provides a general overview of the literature reported to date concerning the nature and reactivity of allenylpalladium intermediates. The coupling of a variety of propargylic electrophiles with aryl boronic acids to form allenes is examined in Chapter 2. However, when employing diastereomerically pure electrophiles, some erosion of stereochemistry was observed in the allene products. This effect was examined further, and epimerisation of the allene product was found to be the origin of the loss of stereochemistry. Evidence for the species likely responsible for this epimerisation is presented. The serendipitous formation of tetrahydrofurans (THFs) from propargylic 7-membered cyclic carbonates prompted an in-depth examination of this reactivity, as described in Chapter 3. The reaction of these cyclic carbonates was rendered stereoselective and the stereochemical outcome of the reaction elucidated. The methodology was extended to propargylic acyclic carbonates which allowed the formation of tetrahydropyrans (THPs). The effect of ring-size and substituents on the cyclisations was examined, culminating in the formation of two rings in a single step from diol-containing bis-carbonates. Chapter 4 describes the extension of this methodology to the formation of azacyclic products. This built upon foundation work conducted by a Part II student within the group, and further improved the selectivity of the reaction. Two diverse azacyclic skeletons could be formed from the same substrate by the employment of different bidentate phosphine ligands, and a variety of substrates were examined under these conditions. Chapter 5 draws general conclusions and sets out possible future directions for the methodology, and full experimental details are outlined in Chapter 6.
Supervisor: Anderson, Edward A. Sponsor: Engineering and Physical Sciences Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Organic chemistry ; Organic synthesis ; Asymmetric catalysis ; Synthetic organic chemistry ; Organometallic Chemistry ; Catalysis ; Physical Sciences ; Chemistry & allied sciences ; Palladium Catalysis ; Saturated Heterocycles ; Allenes ; Oxacycles ; Azacycles ; Asymmetric Synthesis