VCD spectroscopy distinguishes the enamine and iminium ion of a 1,1'-binaphthyl azepine.

We present a VCD spectroscopic characterization of a chiral 1,1'-binaphthyl azepine catalyst and show that the VCD spectra of an in situ generated enamine and an ex situ prepared iminium ion are characteristically different. The study highlights the potential of VCD spectroscopy to distinguish such catalytically relevant stable intermediates and that the spectra can be used to determine the species' dominant conformers in solution.