Studies on the Mechanism of Action of Prekinamycin, a Member of the Diazoparaquinone Family of Natural Products: Evidence for Both sp2 Radical and Orthoquinonemethide Intermediates

Abstract

The putative reductive activation chemistry of the diazoparaquinone antibiotics was modeled with Bu₃Sn−H and prekinamycin dimethyl ether along with prekinamycin itself. Reaction in various combinations of aromatic solvents, with and without the nucleophile benzylmercaptan present, led to isolation of both radical-trapping arene adducts and nucleophilic capture benzyl thioether products. On the basis of these product distribution studies, the intermediacies of, first, a cyclopentenyl radical and, next, an orthoquinonemethide electrophile are postulated.