Conformations of seven-membered rings: the fourier transform model

A representation of the puckered conformations of seven-membered rings, using the Fourier Transform model and derived from the torsion angles, is presented in terms of two puckering amplitudes and their corresponding puckering phases. p]These four parameters are used to describe the main conformational types and to study the planarity of the rings, symmetrical forms, pseudorotation pathways and symmetrical interconversions through the puckering levels. This analysis provides a criterion for characterizing the basic conformations which have already been established by earlier work. A comparison with previous models is also given and the representation applied to some 1,4-benzodiazepine compounds.