Joop A. Peters, G.W.M. van Ballegoyen-Eekhout, B. Graaf
1983
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0
Influential Citations
14
Citations
Journal
Tetrahedron
Abstract
Abstract The stereospecific synthesis of the three isomers of 3,7-dimethylbicyclo[3.3.1]nonane is described. The conformations of these compounds were studied with the use of 13C and 1H NMR spectroscopy. The 3β,7β-dimethyl derivative exists predominantly in the cc conformation, the 3α,7β-dimethyl derivative predominantly in the bc conformation, whereas 3α,7β-dimethylbicyclo[3.3.1]nonane exists as a mixture of the cb bc and the t-bb conformations, which rapidly interconvert. The ΔH and ΔS values for the conformational equilibrium in question, were determined by variable temperature13C NMR. The results of these experiments fit well with those of molecular mechanics. The enthalpies of activation of the interconversion of the various conformers of 3α,7α-dimethylbicyclo[3.3.1]nonane were also calculated and compared with those of the parent system bicyclo[3.3.1]nonane.