C-H Activation Using Boron

Abstract

Aromatic tertiary amines with hydridic methyl, phenyl and benzyl substituents were reacted with catalytic amounts of the boronic Lewis acid tris(pentaflurophenyl)borane, B(C6F5)3. Hydride abstraction was facilitated by B(C6F5)3, activating the tertiary amine to the iminium ion form. The introduction of a nucleophilic allylic trimethysilane led to the formation of two new C-C bonds. The conditions under which such a reaction can occur were successfully optimised and the scope of the reaction was extended. Seven tertiary amines were synthesised and used as hydride donors in the reaction, five of which led to the formation of a cyclised product through B(C6F5)3 facilitated hydride abstraction and intramolecular C-C bond formation. An allyltrimethylsilane species was also synthesised and used as a nucleophile, for which low yields of a cyclised product were seen. Attempts were made to isolate and characterise said products but this proved difficult. Overall, through the use of an alternative solvent and a lower temperature, over the course of fewer hours, the NMR yield of the cyclised product from a previously reported reaction was increased from less than 10% to 43%.

Date of Award	31 Jan 2019
Original language	English
Awarding Institution	The University of Manchester
Supervisor	David Procter (Co Supervisor) & Alexander Pulis (Main Supervisor)