The electrophilic addition of bromine to benzobarrelene in chloroform
at 10 degrees C followed by repeated chromatography combined with frac
tional crystallization allowed us to isolate ten products 12-21 Struct
ural determination of these compounds revealed that the barrelene skel
eton was rearranged completely. 18-21 are alcohol compounds which aris
e from hydrolysis of 12, 13, 14, and 15 respectively. High temperature
bromination of benzobarrelene in decalin at 150 degrees C followed by
repeated chromatography combined with fractional crystallization gave
us 18 products. Nonrearranged products 24, 25, and 26 have been isola
ted in 50% yield. All compounds have been characterized properly, espe
cially by 200 MHz H-1 NMR and 50 MHz C-13 NMR spectra. Furthermore, it
has been concluded that high temperature bromination of bicyclic syst
ems gives more non-rearranged products if the molecule is more straine
d, the tendency to rearrange decreases as in the case of benzonorborna
diene.