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Exploring potential energy hypersurfaces for triple symmetric inversion in 3‐azabicyclo[3.3.1]nonan‐9‐one and its N ‐methyl derivative
Author(s) -
Smeyers N. J.,
Melendez F. J.,
Smeyers Y. G.
Publication year - 1998
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/(sici)1096-987x(19981115)19:14<1567::aid-jcc2>3.0.co;2-h
Subject(s) - conformational isomerism , ab initio , chemistry , potential energy , inversion (geology) , computational chemistry , ab initio quantum chemistry methods , derivative (finance) , molecule , quantum mechanics , physics , organic chemistry , paleontology , structural basin , financial economics , economics , biology
The potential energy hypersurfaces for the triple inversion, from chair to boat and α to β conformations, are explored theoretically in 3‐azabicyclo[3.3.1]nonan‐9‐one and its N ‐methyl derivative, by using ab initio quantum‐mechanical calculations. Both compounds are precursors of rigid analogs of the potential GABA A and GABA B receptor antagonists. In contrast to results from semiempirical calculations, the chair–chair β conformers are found to be, by far, the most stable structures for both the nonmethylated and N ‐methylated compounds. The inversion barriers are found to be relatively low, so that the conformers could be expected to exist in thermodynamic equilibrium at room temperature. A population analysis reveals, however, that, in the ab initio approach, the molecules seem to exist practically only in the chair–chair–β conformation. The theoretical results compare well with the available experimental data. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 1567–1574, 1998