Synthesis of ABC analogues of the antitumour antibiotic streptonigrin

ABC analogues of the antitumour antibiotic streptonigrin, that contain the key metal chelation site and redox-active quinone unit that are essential f or biological activity, were prepared via palladium catalysed cross-couplin g of 2-iodo-8-nitroquinoline or 2-iodo-6-methoxy-5-nitroquinoline with 2-tr imethylstannio-6-methylpyridine. Mild oxidation of the pyridyl methyl group introduced the acid functional group on ring C and Fremy's salt oxidation afforded the quinone unit which was elaborated to give the 5-amino-6-methox y substitution pattern present in streptonigrin. (C) 2000 Elsevier Science Ltd. All rights reserved.