ABSTRACT
The 1,2,3-triphenylcyclopropenyl cation (lla) and cyc\oheptatrienyl cation (112) give, like the heteroaromatic cations, free radicals by one-electron reduction, and these undergo almost quantitative dimerization in aprotic solvents [312,313]. Also lllb undergoes reductive dimerization, with the coupling position being exclusively a phenyl-substituted carbon atom [314]. After reduction of Uc in MeCN only the rearranged dimer, 1,2,4,5-tetraphenylbenzene, was isolated (39%), together with N-acetyldiphenylcyclopropenylamine (24%) formed in a reaction with the solvent [312].
