Graphic representation of configuration in two-dimensional space. Current conventions, clarifications, and proposed extensions.
The chemical vocabulary can describe, in a single term, a racemate or a specific enantiomer or a compound that is enantiopure, but whose absolute configuration is unknown. Regardless of these differentiations, the corresponding conventional graphic representations display but one specific enantiomer. Because of this inflexibility, verbal annotations to stereostructures in chemical publications and databases are unavoidable. In the expanding era of chirotechnology, the limited descriptive power of stereostructures in two-dimensional space is of serious concern. To provide a solution to this problem, targeted redeployment of established stereobonds serve as stereodescriptors that differentiate between enantiopure and racemic compounds and those that are enantiopure but whose chirality sense is unknown. Graphic displays then share the explicitness and accuracy of the chemical vocabulary. Fischer projections, recently expanded to accommodate alkenes and axially stereogenic compounds, can display favorably comparative configurational aspects of molecules with a multiplicity of stereogenic units.
Maehr
Hubert
H
Roche Research Center, Hoffmann-La Roche Inc., Nutley, New Jersey 07110, USA. hubert.maehr@roche.com