This thesis describes the synthesis of methyleneaziridines bearing aryl groups and investigates some of their chemistry, focusing on thermal rearrangements and metal catalysed reactions. The inclusion of an N-aryl group is desirable as it is thought it might facilitate new types of reactions to be developed for use in organic synthesis. In chapter one, the synthesis of methyleneaziridines with N-EWGs and N-aryl groups is investigated. Starting by exploring the possibility of using coppercatalysed nitrene cyclisation, a common method for the synthesis of aziridines, the synthesis of N-tosyl and N-troc methyleneaziridines was attempted. This led into the synthesis of N-mesityl methyleneaziridine which was achieved in 85% yield by ring closure of N-(2-iodopro-2-en-1-yl)-2,4,6-trimethylaniline using sodium amide in ammonia. The effect of the leaving group (Br vs I) on the relative rates of such ring closure reactions was explored and it was established that iodides cyclise at a higher rate. Chapter two describes the thermal rearrangement of N-mesityl methyleneaziridines. A kinetic study was conducted to show the increased propensity for N-mesityl methyleneaziridine to rearrange to the cyclopropylimine, compared to N-alkyl methyleneaziridines. The application of this rearrangement for the preparation of cyclopropylamines was explored. Chapter three looks at metal-catalysed reactions of methyleneaziridines. It was shown that N-mesityl methyleneaziridine will participate in a palladium-catalysed reaction. Carbonylation reaction of methyleneaziridines, as reported by Alper1 and Pauson-Khand reactions were also explored. A novel methyleneaziridine containing cobalt/alkyne complex was produced in 40% yield.