A synthon is a central concept in the field of retrosynthetic analysis. It is defined as a part of a molecule that can take part in any synthesis reaction. In many cases, a synthon corresponds to a functional group and it has to be converted into a synthetic equivalent (a commercially available organic compound that allows synthesis to be initiated). Example
In the retyneynthesis of phenylacetic acid (below), the synthons are the benzyl cation and the carboxy anion:
The synthetic equivalents involved are benzyl bromide and a cyanide, respectively.
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