Development of a System for Translation of Chemical Name into 2D-Structure (V)

Abstract

Translation of IUPAC systematic organic chemical nomenclature into chemical structure has been applied by computer system CHEMNAME to fused and bridged fused ring systems on the basis of IUPAC recommendations 1998. Letter locants of the parent component in fusion descriptors are converted to the numerical numberings going from the atom with locant 1 through sequence of bond that belongs to one ring. Omitted locants at the fusion atoms are recovered in the same way. Recovery is also supported when all locants on a component are omitted e.g. benzo[7]annulene, pyrazino[g]quinoxaline. Numbering proceeds as follows. Duplicated atoms after fusion are compressed to give a connection table of the fused ring system. Ring components are extracted and numbered. Whole sets of rings arranged in a straight line are collected. A ring set is expressed by numberings of rings, of fusion atoms on upper and down sides of the straight ring line. A linear set with maximum number N of rings (J=1 to N) are arranged on axis y=0, each ring being at x=2J-N-1. X,Y-arrangement of each ring is obtained by crossing two linear ring sets at a common ring. Then the starting atom of numbering and clockwise direction around the system are obtained. The real locant set is selected by consideration of the preference rules. Numbering of bridge atoms are ruled in detail by the recommendations and the rules are applied to our system without difficulty.