Determination of Absolute Configuration Using Concerted ab Initio DFT Calculations of Electronic Circular Dichroism and Optical Rotation: Bicyclo[3.3.1]nonane Diones

The concerted use of ab initio time-dependent density functional theory (TDDFT) calculations of
transparent spectral region optical rotation and of circular dichroism has recently become
practicable, permitting the concerted use of transparent spectral region optical rotation and circular
dichroism in determining the absolute configurations of chiral molecules. Here, we report concerted
TDDFT calculations of the transparent spectral region specific rotations and of the circular dichroism
spectra originating in n → π* CO group excitations of four bicyclo[3.3.1]nonane diones, 1−4.
Comparison to experiment yields absolute configurations for 1−4. For each dione, specific rotations
and circular dichroism spectra give identical absolute configurations. Our results are consistent
with previous work, with the exception of the Octant Rule-derived absolute configuration of the
2,9-dione.