Exhaustive generation of organic isomers. 5. Unsaturated optical and geometrical stereoisomers and a new CIP subrule

This work, based on graph theory, presents a US-CAMGEC software developed for analysis, generation, and counting organic unsaturated stereoisomers with isolated or cumulated double bonds in structures that may contain chiral carbon and heteroatoms with variable valences within the molecule. A new extension to N_tuple notation was done for describing accordingly either Z, E, r, or s double bond and R, S stereoisomerism, Algorithms for transforming both constitutional isomer N_tuples to their corresponding graphs and graphs to the corresponding configurational N_tuples were developed. Computational implementation of Cahn-Ingold-Prelog (CIP) rules was developed including a new subrule for discriminating priorities to rank complex ligands already containing chiral stereocenters and having no different atomic number partial ranks. Test results for families of symmetric and nonsymmetric hydrocarbons and their monohalogenated, mono- and dioxygenated, and mono- and dinitrogenated derivatives are presented.