Group 2 Mediated Dehydrocoupling

Abstract

Whilst Group 2 elements continue to emerge from their obscurity, with a plethora of heterofunctionalisation thus described, such extensive investigations into cross metathesis, remain limited. Described herein is an extensive investigation into a variety of factors which contribute to the understanding of the complexity of the mechanistic surface upon which Group 2 mediated catalytic cross- and stoichiometric σ-bond-metatheses sit.An initial study into the synthetic potential of σ-bond metathesis yielded a range of unprecedented and structurally fascinating compounds- mixed metal amidoalkyls and amidohydrides of Groups 1 and 2. Subsequently, a pair of variables in Group 2 mediated dehydrocoupling was investigated:a) The effect of congeneric variation upon Group 2 (magnesium, calcium and strontium) mediated dehydrocoupling of amines and silanes, most notably indicating the significance of ancillary ligation, solution molecularity and precatalyst activation mechanisms.b) The effect of variation in hydridic coupling partner on the dehydrocoupling of a range of amines with 9-BBN, pinacol(borane) and diphenylsilane mediated by a β-diketiminate supported magnesium centre, most notably indicating the profound effect of coupling partner Lewis acidity and contingent variations in catalyst molecularity and rate determining step.Finally, an investigation into the introduction of unprecedented steps in Group 2 catalysis is reported herein. Specifically, the activity of the stable radical TEMPO is investigated for its propensity to induce single electron transfer upon labile, reactive ligands around magnesium and the ability for its anionic analogue to undergo σ-bond metathesis.

Date of Award	9 Dec 2014
Original language	English
Awarding Institution	University of Bath
Supervisor	Michael Hill (Supervisor)