Fenchone, camphor, 2-methylenefenchone and 2-methylenecamphor: a vibrational circular dichroism study

J Phys Chem A. 2006 Apr 20;110(15):4958-68. doi: 10.1021/jp057178y.

Abstract

We report and discuss the infrared (IR) vibrational circular dichroism (VCD) spectra of the enantiomeric pairs of the olefin derivatives of fenchone (1,3,3-trimethyl-2-methylenebicyclo[2.2.1]heptane) and camphor (1,7,7-trimethyl-2-methylenebicyclo[2.2.1]heptane), respectively, together with those of the parent molecules. The VCD spectra were taken in three spectral regions: the mid-IR region, encompassing the fundamental deformation modes, the region of CH-stretching fundamental modes and the NIR-region between 1100 and 1300 nm, which corresponds to the second CH-stretching overtone. The VCD and absorption spectra in the first two regions are analyzed by use of current density functional theory (DFT) calculations. The NIR region is analyzed by a protocol that consists of the use of DFT-based calculations and in assuming local mode behavior: the local mode approach is found appropriate for interpreting the absorption spectra and, for the moment, acceptable for calculating NIR-VCD spectra. The analysis of the first region allows us to track the contribution of the C=O group in the vibrational optical activity of C-C stretching modes; notable differences are indeed found in olefins and ketones. On the contrary, in the other two regions the VCD spectra of olefins and ketones are more similar: in the normal mode region of CH stretching fundamentals the spectra are determined by the mutual orientation of the CH bonds; in the second overtone local mode region olefins and ketones signals show some differences.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Camphanes
  • Camphor / analogs & derivatives*
  • Camphor / chemistry*
  • Circular Dichroism
  • Computer Simulation
  • Models, Chemical*
  • Molecular Conformation
  • Norbornanes / chemistry*
  • Spectrophotometry, Infrared
  • Spectroscopy, Near-Infrared
  • Stereoisomerism
  • Vibration

Substances

  • 2-methylenecamphor
  • 2-methylenefenchone
  • Camphanes
  • Norbornanes
  • fenchone
  • Camphor