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Title: Studies towards the stereoselective radical cyclisation of sulfinimines
Author: Rochette, Elise
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2013
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Chiral amines are an important class of compounds; they are used in many different fields such as drug discovery, materials synthesis and natural product synthesis. Many methods for the synthesis of chiral amines have been developed. The addition of nucleophiles to chiral sulfinimines is a reliable, simple and general method. A large number of reports on the addition of anionic nucleophiles to both the Ellman tert-butanesulfinimines and Davis p-toluenesulfinimines have been described but only a few reports on the use of radical addition to these motifs are present in the literature. This project aims to investigate the diastereoselective radical cyclisation of sulfinimines. To achieve this, a range of sulfinimines were designed and although some proved to be difficult to synthesise a good range of substrates were successfully obtained from heteroaromatic to aliphatic. Radical cyclisation was first carried out using tributyltin hydride and AIBN giving the desired product in good yield and stereoselectivity. Due to the many drawbacks of tributyltin hydride other radical methods have been examined. It was found, the only method to give satisfactory results was using a NHC-borane. Following those preliminary results the scope of the methodology was investigated and sulfinimines ranging from aliphatic to ketimines were successfully cyclised in excellent stereoselectivity and varying yields. In order to expand this methodology to more complex molecules a cascade reaction was investigated. Two xanthate analogues were synthesised and an attempt at cyclisation was made. Anionic cyclisation was also examined under different conditions. Friedel-Crafts acylation of an electron-rich sulfinimine was also investigated. The application of the radical cyclisation of sulfinimines to the synthesis of nakadomarin A was explored. This route proved to be challenging and the precursor to the radical reaction could not be accessed therefore alternative strategies were followed. Those focused on closing the B ring of the natural product through metal-catalysed coupling or Friedel-Crafts acylation.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available