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New heteroaromatic chemistry

Song, Chuanjun. 2005. New heteroaromatic chemistry. PhD Thesis, Cardiff University.

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Abstract

The current literature for the synthesis of pyrazole derivatives has been reviewed. A silver nitrate-induced 5-endo-dig approach to pyrazolines and pyrazoles is discussed. A brief review of the 5-endo-dig cyclisation is included. The propargylic hydrazine precursors are synthesized by four different routes. The key step for the first route is a Mitsunobu reaction of propargylic alcohols with hydrazine derivatives. A short review of the Mitsunobu reaction is also included. The second route applied is a nucleophilic attack onto imines by lithium acetylides followed by electrophilic Anamination of the resulting propargylic amine with a oxaziridine. The third route involves 7V-nitrosation of a propargylic amine and subsequent reduction of the nitroso functional group. The final route is a simple nucleophilic substitution of propargyl bromide with hydrazine. Oxidation of pyrazoline to pyrazole and iodination of pyrazole have also been briefly studied. Two examples of 5-endo-dig iodocyclisation and one example of palladium-induced 5-endo-dig cyclisation are also reported. Current literature for pyrrole acylation has been reviewed. Representative 2-aryl-7V-tosylpyrroles were synthesized by Suzuki coupling of 2-bromo-Af-tosylpyrrole and arylboronic acids. A brief review of Suzuki coupling reaction is included. A new method for the acylation of Af-tosylpyrroles using carboxylic acids and trifluoroacetic anhydride is discussed. When applied to a,/-unsaturated acids, a in situ Nazarov cyclisation follows acylation to give cyclopenta 6 pyrrol-6(l//)-ones. The Nazarov cyclisation is reviewed. TV-Detosylation of acylpyrroles has been briefly examined. A study towards the construction of the macrocyclic core of roseophilin by the new pyrrole acylation strategy is discussed.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Chemistry
Subjects: Q Science > QD Chemistry
ISBN: 9781303201783
Date of First Compliant Deposit: 30 March 2016
Last Modified: 12 Feb 2016 23:15
URI: http://orca.cardiff.ac.uk/id/eprint/56011

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