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Generating structural diversity in \(\alpha\)[alpha],\(\alpha\)[alpha]-difluoromethyl ketones

Fullbrook, Jeremy Jon (2003)
Ph.D. thesis, University of Birmingham.

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Abstract

This thesis describes attempts to use palladium-catalysed cross-coupling methodology in the synthesis of \(\alpha\),\(\alpha\)-difluoroketones contained within a diverse array of molecular motifs. 1-(\(N\),\(N\)-Diethylcarbamoyloxy)-2,2-difluoro-1-(tributylstannyl)ethene undergoes Stille cross coupling with a variety of aryl, heteroaryl, vinyl and allyl organic electrophiles. Conditions, which promote in situ transmetallation to a more reactive copper intermediate, were essential for obtaining significant quantities of product. 1-(\(N\),\(N\)-Diethylcarbamoyloxy)-2,2-difluoro-1-iodoethene also underwent coupling with a range of aryl, heteroaryl and vinyl stannanes. Due to the difficulties with cleavage of this protecting group, the synthesis and potential application of an \(N\)-ethyl-\(N\)-(2-methylallyl)carbamate has been studied. A 2-methoxyethoxymethyl (MEM) protecting group strategy proved very successful for the synthesis of a range of difluoromethyl aryl ketones. Two consecutive coupling reactions were possible from a difluoroenol stannane, in which coupling of initial styrene products bearing a triflate group afforded a range of biarylethenes. Cleavage occurred under mild electrophilic conditions with protic, halogen, sulfur and carbon electrophiles. Diene products have been tested for reactivity in Sharpless Asymmetric Dihydroxylation. A 1,4-diene has been converted through to a fluorinated analogue of a dideoxyxylulose. A 1,3-diene has been successfully converted through to a difluorodeoxyxylulose of current interest. Key points involve regioselective and highly enantioselective dihydroxylation of the non-fluorinated olefin. Application of a special protecting group for the allylic alcohol was essential, as was control of the pH of the reaction medium.

Type of Work:Ph.D. thesis.
Supervisor(s):Percy, Jonathan M. and Cox, Liam
School/Faculty:Schools (1998 to 2008) > School of Chemical Sciences
Department:Chemistry
Additional Information:

Includes Addendum/corrigenda, typographical errors have been corrected.

Keywords:Difluoroketones, fluorosugars
Subjects:QD Chemistry
Institution:University of Birmingham
Library Catalogue:Check for printed version of this thesis
ID Code:98
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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