Advances in Amination of Nitrogen Heterocycles

This chapter discusses primarily the advances made in the amination of nitrogen heterocycles. Furthermore, because of the vast number of recent publications and patents describing the standard technology of conversion of hydroxy-N-heterocycles into the corresponding chloro derivatives, only the general problems connected with this method as well as some pertinent applications of this standard methodology are analyzed. The rate of attack of amines on nitrogen heterocycles containing a leaving group X, followed by subsequent elimination of X, is dependent on the nature of (a) the heterocycle, (b) the amine, (c) the solvent, and (d) the leaving group. The structure of AE intermediates in heteroaromatic as well as aromatic nucleophilic substitution is examined, and evidence is presented for single-electron transfer in some cases. The reactivity factors in aminations include reactivity of different nitrogen heterocycles, reactivity of different amines, influence of solvents, and the effect of the leaving group. The chapter also discusses the comparison of several amination methods.