Remarkable dynamic NMR spectra and properties of a sterically congested cis-1,2-diarylcyclobutane
Abstract
Dimethyl 2.2′-dichloro-6,6′-dimethoxy-β-truxinate 2 displays in solution, by 1H NMR spectroscopy, a mixture of two conformers: a meso conformer and a racemic conformer. The other possible meso conformer may be present in a small amount in solution. The NMR parameters of these conformers were extracted from their low-temperature static 1H and 13C spectra. The conformers interconvert mainly by a mechanism involving rotation of one aryl group at a time. Activation parameters of the same dynamic process were obtained by band-shape simulations from four different regions of the variable-temperature 1H spectra. In one spectral region, rate constants in excess of 106 s–1 were recorded.