Coenzyme models, 21. Oxidative trapping of carbanion intermediates by a flavin immobilized in cationic polymers

Abstract

AbstractAromatic aldehydes 5 and α‐keto acids 8 in the presence of cyanide ion, which usually give the benzoin condensation products, were converted oxidatively to the corresponding benzoic acids 10 by the catalytic action of the title flavin. The change in the reaction route cannot be achieved completely by flavin 1. Product analyses and kinetic measurements established that the carbanion intermediate, \documentclass{article}\pagestyle{empty}\begin{document}${\rm R}\hbox{---} \mathop {\rm C}\limits^ \ominus \left( {{\rm OH}} \right)\left( {{\rm CH}} \right)$\end{document}, which is formed through rate‐limiting deprotonation or decarboxylation of the cyanide‐adducts, is oxidized immediately by the title flavin. The influence of polymer structure on the efficiency of flavin trapping is discussed.