Synthesis of the naphthoquinone nucleus of awamycin

Article abstract of DOI:10.1021/jo00119a018

A synthesis of ketone 4, corresponding to the fully elaborated naphthoquinone nucleus of awamycin, is described. The synthesis involves the Diels-Alder reaction between diene 8 and quinone 9 to construct naphthoquinone 10, the coupling of bromide 15 and an ansa chain surrogate 17 via an aryllithium intermediate, and a late stage 1,4-addition of NaSMe to naphthoquinone 23 to afford the ketone 4.