Configurational and conformational study of new esters derived from 2-methyl-2-azabicyclo[2.2.2]octan-5-syn(anti)-ols by NMR spectroscopy and x‐ray crystallography—I

Abstract

A series of esters derived from syn- and anti-2-methyl-2-azabicyclo[2.2.2]octan-5-ols were synthesized and studied by 1H, 13C and 2D NMR spectroscopy. The crystal structure of 5-syn-(3,5-dichlorobenzoyloxy)-2-methyl-2-azabicyclo[2.2.2]octane was determined by x-ray diffraction. The unambiguous assignment of all bicyclic proton and carbon resonances was achieved by the combined analysis of the 1H–13C correlation spectra and double resonance experiments. The 1H–1H coupling constants are proposed as model values in order to carry out the analysis of other isoquinuclidine derivatives. In order to gain additional information, a conformational analysis using molecular modeling techniques was undertaken. © 1997 John Wiley & Sons, Ltd.