The oxidation of hexahelicenes. Synthesis of hexahelicene‐5,6‐quinone

The remarkable ease with which 1,3,14,16‐tetramethylhexahelicene can be oxidised has to be ascribed to the electronic effect of multiple methyl substitution and not to disturbance of the helical conformation, as might be concluded from the polarographic oxidation potentials of hexahelicene and some of its methyl derivatives. Oxidation of hexahelicene with chromic acid in acetic acid gives hexahelicene‐5,6‐quinone in 70% yield. Its structure was proven by spectroscopic methods.