Research on 1-azabicyclic systems

The enthalpy of the cis-trans conversion of quinolizidine was calculated by two independent methods on the basis of the literature data on the heat content of decalins, the difference in the enthalpies of the N-H-axial and N-H-equatorial conformations of piperidine, and the hydrogen bond energies in the quinuclidine-phenol and quinolizidine-phenol systems. The calculations yielded ΔH values of 3.7 and 4.3 kcal/mole for gaseous quinolizidine and 3.3 kcal/mole in favor of the trans-fused form for the liquid.