Synthetic hydroxyrotenoids

Abstract

The total synthesis of two isomeric pentacyclic 11-hydroxyrotenoids, 4′,5′,6a,12a-tetrahydro-11-hydroxyfurano-[3′,2′:8,9]rotoxen-12(6H)-one and 4′,5′,6a,12a-tetrahydro-11-hydroxyfurano[2′,3′:9,10]rotoxen-12(6H)-one, and the novel 9-hydroxyrotenoid, 4′,5′,6a,12a-tetrahydro-9-hydroxyfurano[3′,2′:10,11]rotoxen-12(6H)-one is described. These racemic compounds have been shown, by ¹H n.m.r. studies, to possess a cis-fused B/C ring junction, as in the natural rotenoids. The cyclisation reaction for preparing 6a, 12a-dehydrorotenoids is discussed and a mechanism is suggested.