Re-examination of the anodic dimerization of enamines, 2-cyano-2-phenylvinylamines, using the Austin model 1 method

Dimerization of cation radicals derived from 2-cyano-2-phenylvinylamines (1 ) to produce diphenylmethane derivatives (Ph-CH(CN)-C6H4-C(CN)=CH-(NRR3)-R- 2, 2) was re-examined by the AM1 (Austin model 1) method. However, dimeriza tion of cation radicals derived from 1 was forbidden by calculation of the total energies of the dimers. An alternative reaction mechanism for the for mation of 2 was proposed. Hydrolysis of cation radical (A) derived from N,N -dimethyl-2-cyano-2-phenylvinylamine (la) gives a cyanophenylmethyl radical (F), which attacks at la to give a radical (G). Following anodic oxidation of G, deprotonation gives phenyl-[4-(1-cyano-2-dimethylaminovinyl)phenyl] acetonitrile (2a) as the final product.