The Oxidation of (±)-Reticuline as Studied by E.S.R Spectroscopy

Abstract

E.s.r. spectra obtained by oxidation of reticuline and closely related compounds in a flow system with cerium(IV) show chiefly the aryloxy radical derived from the 1-benzyl c-ring. The 4′-ethoxy homologue of norreticuline shows both A- and C-ring radicals in roughly equal proportions. The mechanism of intramolecular coupling is discussed, and as no evidence was obtained for the occurrence of a radical substitution reaction it is concluded that radical pairing is more likely, although this apparently happens too quickly for observation of a biradical species.