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The development and use of novel green radical methodology

Over the last forty years the steady use of radical reactions as the key steps in syntheses has increased. The most commonly used radical reagent is tributyl tinhydride. However such tin based radical reagents are toxic and often contaminate the product as they are difficult to remove. As an alternative to these tin reagents, a novel NaBH4/U.V. system was developed. This system was successfully used to effect the radical reduction of various aromatic halides. In light of these results it was thought that other useful transformations such as C-C bond formation could be achieved. Radical cyclisation onto unsaturated bonds, halogen atom transfers radical cyclisation (HATRC) and 1-5 hydrogen atom translocations were explored. This, 1-5 hydrogen atom translocations, methodology has been successfully applied to the synthesis of the spirocyclic natural products (±) horsfiline and coerulescine. With this success the use of the NaBH4/U.V. system on pyridine substrates was explored. Unfortunately this was not achieved with our current understanding of this reaction. However the use of tributylgernamium hydride, which is considered a ‘green’ radical reagent when compared to tin based reagents, proved successful. The novel application of this reagent in the 1-5 hydrogen atom transfer reaction on pyridine substrates was successfully demonstrated. Its use was successfully employed in the synthesis of a pyridine based bioisostere derivative of horsfiline.

Identiferoai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:531868
Date January 2010
CreatorsIshaq, Ahtsham
PublisherUniversity of Aberdeen
Source SetsEthos UK
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation
Sourcehttp://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=158370

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