Circular dichroism and conformational analysis of diastereomeric bicamphors

Stereospecific syntheses afforded endo,endo- (1) and exo,exo- (2) bicamphor s, while the third possible diastereomeric exo,endo-bicamphor (3) originate d from nonselective camphor radical dimerization. The stereochemistry of bi camphor linkage was confirmed by H-1 NMR analysis. Chiroptical and ultravio let spectral data are presented for the three diastereomers 1-3 to show int erchromophoric interaction. Conformational analysis to evaluate the relativ e orientation of each pair of carbonyl chromophores was accomplished by H-1 NMR spectroscopy and molecular mechanics calculations.