Electrolytically initiated intramolecular cyclization of 2-nitrobiphenyl-2'-carboxylic acid

Abstract

Controlled-potential electroreduction at mercury cathodes of 2-nitrobiphenyl-2'-carboxylic acid(I) and of its ethyl ester (III) shows that a follow-up intramolecular cyclisation occurs leading prevalently to the corresponding lactam (phenanthridone, reaction (1h)) or to the hydroxamic acid ( N-hydroxyphenanthridone, reaction (1a)). The intermediates are the hydroxylamino and the amino derivatives. It follows from comparison of polarographic measurements, cp coulometry and preparative electrolysis that the reduction does not take place here as cp-electrolysis and the competition of non-electrolytical mechanisms must be taken into account.