Applications for the activation of hydroxyl groups to nucleophilic attack

Awheda, I.M., 2012. Applications for the activation of hydroxyl groups to nucleophilic attack. PhD, Nottingham Trent University.

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Abstract

This thesis investigates the applications of the activation of hydroxyl groups to nucleophilic attack within three key areas: Cyclic five-membered thionocarbamates bearing a N-Boc group undergo ring opening reactions at the 5-C with soft nucleophiles such as thiophenolate, pyridine-2-thiolate and potassium thioacetate. Hard nucleophiles react at the thiocarbonyl group followed by a variety of successive reactions involving breakage of C-N ( e. g. with n-BuLi) or C-O bond (e. g. with PhLi). Treatment with iodide under microwave conditions led to a rearrangement to a thiazolidin-2-one. Two approaches to the synthesis of vic-dithiols were investigated. The more successful approach involves reaction of the trithiocarbonate dianion with cyclic sulphate esters of vic-diols to yield a protected version of the vic-dithiols. In a second approach, rearrangement of thionocarbonates with bromide gave the oxathiolan-2-one. Under thionation conditions with (e. g. Lawesson‟s reagent and HMDO) it was possible to replace both oxygens, while with Lawesson‟s reagent and HMDO in dry xylene only the carbonyl group was replaced. It was not possible to rearrange this material again with bromide or iodide. New chiral organosulphur donors related to TTF and bearing multiple hydroxyl groups (from two to eight) were prepared starting from reaction of [(4R)-2,2-dimethyl-1,3-dioxolan-4-yl]methyl trifluoromethanesulphonate with 2-thioxo-1,3-dithiole-4,5-dithiolate and several further steps. A triiodide complex of a tetrahydroxy substituted donor was prepared and structurally characterized.

Item Type: Thesis
Creators: Awheda, I.M.
Date: 2012
Divisions: Schools > School of Science and Technology
Depositing User: EPrints Services
Date Added: 09 Oct 2015 09:33
Last Modified: 09 Oct 2015 09:33
URI: http://irep.ntu.ac.uk/id/eprint/13

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