What is the preferred conformation of the bicyclo[4.4.1]undecan-11-one ring system? This study presents the first conformational analysis of a bicyclo[4.4.1]undecan-11-one system. Based on low-temperature13C NMR line-broadening measurements and an X-ray structure of the 1,6-dibromo derivative (2), this ketone adopts a chiral conformation with approximate C2symmetry about an axis containing the >C=0 bond. The researchers utilize low-temperature 13C NMR line-broadening measurements and X-ray crystallography to determine the preferred conformation of this ketone, identifying a chiral conformation with C2 symmetry. The observed NMR line-broadening results are consistent with a dynamic interchange of M and P enantiomeric C2conformations, or expressed another way, the "effective" development of an additional C symmetry plane bisecting the molecule at right angles to the plane containing the one carbon bridge (overall average C2vsymmetry). This study provides valuable insights into the stereochemistry and dynamics of this unique ring system. This process has a ΔH barrier of 42 kJ mol1for ketone 1 (43 kJ mol1for 2).
Published in the Canadian Journal of Chemistry, this paper fits within the journal's scope by presenting original research in organic chemistry and structural analysis. The application of NMR and X-ray techniques to determine the conformation of a novel molecule is a key area of interest for the journal's readership.