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Diastereocontrolled synthesis of hetero- and carbocycles via manganese(III) and copper(II): towards a novel prostaglandin total synthesis

Abstract:

The prostaglandins are a unique family of natural products found in all mammalian life, including humans. Their biological significance is profound, and they are responsible for a vast array of bodily functions. This importance, coupled with their low concentration in vivo, has made them attractive targets for total chemical synthesis.

The work herein describes synthetic efforts towards their synthesis using an oxidative radical cyclisation to construct the key [3.3.0]-bridged bicyclic lactone, from which the prostaglandin skeleton may be derived. Key to this was the development of manganese(III) acetate and copper(II) triflate as optimal reagents for this cyclisation of unsaturated malonate/malonic acid derivatives. To study this, several model substrates for this crucial cyclisation were synthesised, and their cyclisation analysed.

Chapter 5 describes the design and synthesis of several model substrates containing malonate groups for the oxidative radical cyclisation. The results of the cyclisation with manganese(III) and various copper(II) salts influenced the design of the substrates, and led to the use of malonic acids as more effective substrates for the formation of [3.3.0]-bicyclic lactones. A catalytic process, in which atmospheric oxygen is the terminal oxidant was also developed.

Chapter 6 describes the studies towards a total synthesis of the prostaglandin family. Two potential routes are followed, the first of which used a key asymmetric epoxidation to install asymmetry. A Suzuki coupling was used to deliver the desired diene required for the cyclisation substrate, which was successfully cyclised using manganese(III) acetate and copper(II) triflate, creating the desired [3.3.0]-bicyclic lactone in good yield and with excellent diastereomeric control. A second, shorter route to the same lactone was also developed, using a novel asymmetric deconjugative aldol condensation to establish asymmetry. Cyclisation of this analogous substrate was also successful, delivering the same lactone after olefin metathesis.

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Institution:
University of Oxford
Division:
MPLS
Department:
Chemistry
Sub department:
Organic Chemistry
Research group:
Burton, Jonathan
Oxford college:
Trinity College
Role:
Author
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Division:
MPLS
Department:
Chemistry
Role:
Author

Contributors

Division:
MPLS
Department:
Chemistry
Role:
Supervisor


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Funding agency for:
Docherty, P


Publication date:
2008
Type of award:
DPhil
Level of award:
Doctoral
Awarding institution:
Oxford University, UK


Language:
English
Keywords:
Subjects:
UUID:
uuid:6ca5556a-3d2d-454a-abbd-0a3a269c5724
Local pid:
ora:10677
Deposit date:
2015-03-20

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