Access

Research Highlights

Nature Chemistry (18 July 2008) | doi:10.1038/nchem.39

Nucleophilic substitution: Sigma in sight

Jane Morris

The transition state of a nucleophilic aromatic substitution reaction has always been presumed to be a |[sigma]| complex. However, the transitory nature of such species has meant that they have so far not been observed experimentally in these reactions, although they have been seen in cases in which the final elimination step is unfavourable, leading to a build up of the |[sigma]| complex.