Circular-dichroism power of chiral, bridged, aromatic compounds. 7,8,15,16-Tetrahydro-7,15-methanocycloocta[1,2-a:5,6-a′]dinaphthalene derivatives

The circular dichroism (CD) and UV spectra of chiral bridged aromatic compounds, 7,8,15,16−tetrahydro-7,15-methanocycloocta[1,2-a:5,6-a′]dinaphthalene-8,16 -diol [(-)-1] and −8,16- dione [(-)-2], have been theoretically calculated by application of the π-electron self-consistent- field-configuration-interaction-dipole-velocity molecular orbital (SCF-CI-DV MO) method. The shape of component CD and UV bands was approximated by the Gaussian distribution method (A), or by employing the observed band shape of the UV spectra of model compounds (method B). The calculated CD and UV curves were in good agreement with the observed ones. For compound (7S,8R,15S,16R)-(-)-1, method A: calcd. CD, λext 237.0 nm (Δϵ −319.2), 224.2 (+ 344.9), A = −664.1; obsd. CD, λext 233.0 nm (Δϵ −671.0), 222.3 (+ 194.6), A = −865.6. The calculated CD and UV spectral curves of compound 1 obtained by the application of method B were in excellent agreement with the observed ones: calcd. CD, λext 233.6 nm (Δϵ −740.8), 222.2 (+ 265.0), A = −1005.8; obsd. CD, λext 233.0 nm (Δϵ −671.0), 222.3 (+ 194.6), A = −865.6. For compound (7S,15S)-(-)-2, method A: calcd. CD, λext 256.4 nm (Δϵ −69.4), 220.3 (+ 103.5); obsd. CD, λext 254.4 nm (Δϵ −89.0), 217.0 (+ 222.1). The absolute configurations of chiral, bridged aromatics (-)-1 and (-)-2 have thus been established.