Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.658454
Title: Catalytic asymmetric carbon-carbon bond formation using alkenes as alkylmetal equivalents
Author: Maksymowicz, Rebecca Marie
ISNI:       0000 0004 5353 7338
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2014
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Abstract:
The development of new methods for carbon-carbon bond formation is a challenging topic at the heart of organic chemistry. Over the past ten years a number of methods for the catalytic asymmetric 1,4-addition of organometallic reagents such as Grignard, organozinc and organoaluminium reagents have been reported. However these reagents suffer from many limitations, including the need for cryogenic temperatures, which prevent their widespread use. Here we have developed a new asymmetric method: the copper-catalysed enantioselective 1,4-addition of alkylzirconium compounds, generated in situM/em>, from alkenes. A general introduction into the formation of carbon-carbon bonds and catalytic asymmetric 1,4-addition reactions is first given. We then focus our attention on hydrometallation reactions and their current use in the addition of alkenyl and alkyl groups in asymmetric 1,4-addition reactions. In Chapter two, we introduce the development of our methodology. We found that by using copper complex (S,S,S)-A, high enantioselectivities can be achieved (up to 96% ee), in the presence of a broad range of functional groups which are often not compatible with comparable methods using pre-made organometallic reagents. The method gives good enantioselectivity at room temperature, in a wide range of solvents, using readily available alkenes. Chapter three discusses the expansion of our method to the 1,4- and 1,6-addition to complex steroids. Modified conditions were then found to enable the addition to β-substituted enones, to form quaternary centres. This is followed by the successful addition to α,β-unsaturated lactones, another difficult substrate class. All these results gave excellent selectivity. In summary, we have developed a new reaction which offers an alternative to current methods reported in the literature. This robust reaction can tolerate a variety of functional groups and we hope that this will aid in the synthesis of important molecules.
Supervisor: Fletcher, Stephen P. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.658454  DOI: Not available
Keywords: Asymmetric catalysis ; Catalysis ; Organic chemistry ; Organic synthesis ; Organometallic Chemistry ; Zirconium ; Conjugate addition ; Copper catalysis ; Asymmetric Synthesis
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