NMR study of the stereochemistry of 2,4,6,8-tetraaryl-3,7-diazabicyclo[3.3.1.]nonan-9-ones

摘要

The ~1H and ~13C NMR spectra of 2,4,6,8-tetraaryl-3,7-diazabicyclo[3.3.1.]nonan-9-ones were measured at 360 and 90 MHz, respectively. The chemical shifts were assigned unambiguously using one-and two-dimensional NMR spectroscopic data and nuclear Overhauser enhancement studies. These results clearly indicate a chair-boat conformation for these compounds with (i) all aryl groups orientated equatorially and (ii) the aryl groups of the boat lying in the shielding zone of the aryl groups of the chair. Literature assignments of carbon chemical shfits were also revised.