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Title: Radical cascades in synthesis
Author: Gladwin, Amanda R.
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 1996
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Nature utilises several modes of construction to synthesise a plethora of important polycyclic natural products. This is illustrated in a brief summary in the Introduction which describes the electrophilic processes involved in terpene biosynthesis. The attempts made by synthetic organic chemists to mimic these electrophilic reactions are then described, and the concept of exploiting tandem, free radical reactions in such processes is then introduced. Chapter Two examines the uses of tandem, free radical processes with the ultimate goal of an efficient and flexible synthesis of the CD-ring portion found in vitamin D3. A review of investigations into the use of tandem radical macrocyclisation-transannulations and also sequential radical cyclisations is presented as the background to our work in this area. Application of these strategies towards the synthesis of the CD-portion of vitamin D3 has culminated in the synthesis of a range of interesting substituted 5,6- and 6,6- ring fused carbobicycles. A related study of radical-mediated transannulation reactions in medium and large ring, naturally occurring terpenes is described in Chapter Three. Successful transannulation of the II-membered ring sesquiterpene humulene, via a radical addition-transannulation process, is presented along with a discussion of product manipulation to provide a crystal suitable for X-ray analysis. Finally, our attempts to cyclise the diterpenes (+)-cembrene, (+)-isocembrene and (+)-cembrenene under a variety of similar radical conditions are then detailed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Organic chemistry Chemistry, Organic