Stereochemistry of [2.2]Metacyclophanes

Increasing numbers of investigations have been carried out on bridged aromatic compounds, the independence of which was very recently acknowledged in the class name “phanes”. Special attention is being attracted by the [2.2] metacyclophanes, whose molecular architecture raises many interesting theoretical questions, mainly with regard to intramolecular steric and electronic interactions. In the present progress report, a short description of the classification and nomenclature of the phanes is followed by a discussion of new physical and chemical aspects of the stereochemistry of [2.2] metacyclophanes and a number of related [2.2] phanes with other aromatic nuclei.