C,C- and C,N-linked dimers and 4-arylmethyl derivatives from 4-arylmethylene pyrazol-5-ones and isoxazol-5-ones with 2-arylbenzimidazolines

Article abstract of DOI:10.1016/0040-4020(95)00970-1

2-Arylbenzimidazolines (8), generated in situ from o-phenylenediamine (7) and the appropriate arylaldehydes, by reaction with 4-arylmethylene pyrazol-5-ones (1) or isoxazol-5-ones (2) produce the 4-arylmethyl derivatives (3) or (4) and the C,C- (5) or the C,N-linked dimers. The reaction was rationalised on the basis of the role of 2-arylbenzimidazoline as a reducing agent and proceeds by a non-chain, free radical process involving one-electron transfer.