Studien in der Lumiflavin‐Reihe V. Spezifische Reaktivität 8‐ständiger Substituenten am Isoalloxazin‐Kern Flavin‐Dimere

The 8‐methyl group of riboflavin and lumiflavin is shown to be activated, in agreement with B. & A. Pullman's LCAO‐MO‐model. Chemical evidence for this is given by reactions of 8‐chloro‐7,10‐dimethyl‐flavin with nucleophilic agents, of 8‐methylflavins with NO and CO groups, and by the base‐catalysed dimerisation of 8‐methylflavins giving rise to a new class of flavin‐like pigments. The particular redox‐behaviour of these “biflavins” is described and their possible biochemical importance is discussed.