Outline of Contents

  1. Introduction
    Conformational isomers
  2. Stereogenic centres
    Configurational isomerism and chirality
    Identifying stereoisomers
  3. Stereogenic axes
    Achiral molecules with chiral centres
    Allenes, biaryls and helicenes
  4. Enantiomers
    Central chirality at atoms other than carbon
    Properties of enantiomers
  5. Diastereoisomers
    Defining features of diastereoisomers
    Relationships between atoms (or groups) within a molecule
  6. Separation of enantiomers
    Resolution via salt formation or derivatisation
    Kinetic resolution
  7. Analysis of enantiomers
    Enantiomeric purity and the enantiomeric excess (e.e.) scale
  8. Stereoselective reactions
    Stereospecific and stereoselective reactions
    The mechanistic basis of stereoselectivity
    Generating stereogenic centres with achiral or chiral substrates

Recommended Reading and Support


A series of exercises to accompany each of the eight topics can be downloaded using this link (PDF, opens in new window).

Background and Acknowledgements

The aim of this course is to foster an understanding of the key stereochemical relationships (enantiomeric, diastereoisomeric, configurational, conformational) in compounds with stereogenic centres and/or axes. The analysis extends to the mechanistic principles of stereoselectivity in synthetic reactions. Interactive molecular models are included so that structures can be explored in depth. The modelling software used is the JSmol molecular viewer.

The original version of this site supported a UG chemistry unit entitled Structural Relationships in Organic Chemistry, provided for Level 2 MChem students in the School of Chemistry of the University of Manchester. The web files were revised to improve their device compatibility and visual quality, and once again I thank Stuart Anderson for providing the template which made this task straightforward. This revision was completed during the COVID-19 lockdowns of 2020-2021.

Tim Wallace
Manchester, April 2021