Renowned authors from 14 countries have contributed to this book. It consists of 24 chapters on the state-of-the-art of the synthesis of nonaromatic nitrogen heterocycles, including recent developments in the most widely used reactions and also in new ones. Enantioselective synthesis and catalysis, and topics such as photocatalysis, microwave-assisted synthesis, ionic liquids and others, are also covered. The first 14 chapters after the introduction are dedicated to the synthesis of rings having one specific size, namely three-, four-, five-, six- and seven-membered rings, single or fused to other rings, in order of increasing ring size. Some concentrate on specific reactions such as cycloaddition reactions, hydroamination and dearomatization reactions, others inspect the many ways possible to obtain a specific ring. Later chapters cover topics such as the reactions of oximes and the reactions of nitrones, enantioselective radical reactions, the utilization of microwaves in synthesis, biocatalysis and photocatalysis. Sustainable procedures for obtaining nitrogen-containing heterocyclic salts are discussed, and the final chapter considers non-covalent interactions and how they can influence the synthesis of N-containing heterocycles, as well as catalysis and materials design.