Specification of Configuration and Conformation
This chapter is concerned with the specification of configuration and conformation of organic compounds. Although certain retained names imply their own stereochemical description, systematic stereodescriptors denoting the configuration of an organic compound are added to a name that does not itself prescribe configuration. This chapter describes two kinds of stereodescriptors, Cahn-Ingold-Prelog (CIP) stereodescriptors and non-Cahn-Ingold-Prelog (CIP) or traditional stereodescriptors. The set of sequence rules established by Cahn-Ingold-Prelog, and extended by others, to establish an order of precedence of atoms and groups around a chiral center, axis, or plane, the direction of which differentiates two configurations is described. The application of the Cahn-Ingold-Prelog stereodescriptors and the non-Cahn-Ingold-Prelog (CIP) or traditional stereodescriptors for stereogenic units in a wide variety of compounds encountered in organic chemistry, both acyclic and cyclic, and compounds with both rings and chains, is described. Compounds named by phane nomenclature and fullerene nomenclature, are included. Tetrahedral configurations for elements other than carbon and nontetrahedral configurations are also covered. The chapter concludes with a section on conformations and conformational descriptors.