New reactions of 2-methyleneaziridines

Abstract

Chapter One reviews the synthesis, properties and reactions of 2-methyleneaziridines, the subject of this thesis. Chapter Two describes the use of these heterocycles in the development of a new four-component synthesis of biologically important α-aminophosphonates. This new chemistry proceeds in moderate to good yield via a “one-pot” process that involves the sequential formation of three new intermolecular bonds and a quaternary carbon centre. This reaction is tolerant to a range of functionalities incorporated in the various components. Deprotection of one of these α-aminophosphonates to the corresponding α-aminophosphonic acid is achieved via a two-step process in very good yield. Chapter Three discusses efforts made towards the development of a multi-component imino Diels-Alder reaction for the generation of 2,3-dihydro-4-pyridones. Initial work suggests acyclic ketimine intermediates are unsuitable for this process. Chapter Four reports unsuccessful attempts made to generate methyleneaziridines bearing electron-withdrawing substituents via in situ N-derivatisation. In Chapter Five, the synthesis of 1,1-disubstituted tetrahydro-β-carbolines from methyleneaziridines is described. The reaction is shown to proceed in moderate to very good yields and a range of β-carbolines were successfully synthesised. High levels of diastereocontrol are demonstrated using a substrate containing a pre-existing stereocentre. Chapter Six details the experimental procedures and characterisation data for the novel compounds produced