O. Červinka

Cyclic Enamines and Imines

Publisher Summary This chapter reviews the properties, methods of preparation, and reactions of heterocyclic compounds possessing the so-called enamine grouping. It also discusses the reactions of enamines obtained from aliphatic or alicyclic carbonyl compounds and those from secondary heterocyclic bases, which are very interesting from the preparative point of view. The chapter begins with the structure and physico-chemical properties of enamines. The existence of an enamine grouping in a molecule makes possible several interconvertible isomeric structures. This fact is responsible for the high reactivity of these compounds. Furthermore, unsaturated amines in which the double bond is separated from the nitrogen atom by at least one saturated carbon atom show a behavior typical to saturated amines and non-conjugated olefins. A double bond in the position α, β to the nitrogen atom leads, by contrast, to the formation of a new reactive grouping in which the free electron pair of nitrogen is conjugated with the π-electrons of the double bond. The character of both the original structural elements is considerably changed.