Applications for the activation of hydroxyl groups to nucleophilic attack

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.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

Nottingham Trent University

Year dc:date.issued

2012

Author dc:creator

• Awheda, IM

Language dc:language

en