Development of new flavin-catalysed reactions

Abstract

Synthetic riboflavin mimics have been utilised for the development of a range of environmentally friendly sulfide oxidation reactions. The mechanics of these reactions, and their context in the wider body of science, is discussed. Reagents for the formation of sulfoxides and sulfoximines with flavins are presented. Hydrazine is shown to be a flavin reductant, and this reduced flavin is able to use atmospheric oxygen as a terminal oxidant to yield a range of sulfoxides from sulfides at low catalyst loading, in good to excellent yields. Hydroxylamine is used to generate sulfoxides from the corresponding sulfide. The kinetics of this reaction are investigated, with continuous flow NMR spectroscopy and this evidence is used to propose a mechanism. The interaction of sodium azide with flavin is investigated in an attempt to understand and prevent the flavin degradation, in an effort to develop an environmentally benign procedure for sulfur-nitrogen bond formation. Additionally, it was also found that ammonium carbamate can be used for the one-step formation of sulfoximines from their corresponding sulfides. This reaction similarly suffers from the flavin decomposition observed between sodium azide and flavin (which leads to catalyst deactivation), and methods to halt this degradation are investigated.

Date of Award	22 Nov 2018
Original language	English
Awarding Institution	University of Bath
Supervisor	David Carbery (Supervisor) & Keith Butler (Supervisor)