HIGH-TEMPERATURE BROMINATION VI1 - BROMINATION OF BENZOBARRELENE

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.