Cahn-In Gold-Prelog R/S System Revisited: Simplifying Assignment of Configuration in Chiral Compounds

Abstract

A practically useful method following Cahn-Ingold-Prelog R/S system is described for establishing R/S configuration in chiral compounds. The method is based on the fact that in a given tetrahedral chiral carbon sequential rotation of any three groups in any of the four triangular formats does not affect the configuration. This provides an opportunity to rotate the three groups particularly including the lowest priority group either in a clock- or anticlock wise manner till the lowest priority group is behind the plane of the paper and thus viewing the molecule from the front for establishing R/S configuration. The utility of the method has been demonstrated in chiral compounds involving both cyclic and acyclic structures bearing one/two carbon atom(s).