Synthesis of a dynemicin A analog without the nitrogen

Abstract

By combining the arylstannane 5 and the cyclohexenyl triflate 6 in a palladium-catalyzed cross-coupling reaction the ring system 7 was established. After attachment of an enediyne group and macrocyclization by a fluoride-induced reaction of 17a the dynemicin A analog 19 was obtained. The X-ray analysis of 19 revealed that the aryl ring is rotated with regard to the aryl system in dynemicin A. One can thus conclude that in dynemicin A the nitrogen heterocycle serves to fix the conformation of the anthraquinone part with respect to the enediyne.