Exploitation of stereochemistry

Most organic molecules incorporate at least one stereogenic element (centre, plane or axis) [26] and may, therefore, exist in more than one stereoisomeric form. These stereoisomers, as far as mechanistic argument is concerned, are distinct species, and the kinetics and 

Loss of stereochemical integrity during a chemical reaction is usually taken as good evidence that the products have been formed via an intermediate incapable of sustaining stereochemical information, but there are alternative explanations (competing concerted processes or equilibrations of stereoisomeric products under the reaction conditions) and these should be considered and excluded where possible by other experiments. 

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