Chemical studies of the Proteaceae. VIII. The conversion of grevillol into rapanone and experiments on the synthesis of ardisiaquinone A

Abstract

Oxidation of grevillol dimethyl ether gave 2-methoxy-6-tridecyl-1,4-benzoquinone which on Thiele-Winter acetoxylation afforded the triacetate of 5-methoxy-3-tridecylbenzene-1,2,4-triol. Hydrolysisfollowed by oxidation and demethylation then yielded rapanone.By the application of a known reaction sequence involving the Stevens rearrangement, dodec-6-ynedioic acid was converted into 5,5'-(hexadec-8-yne-1,16-diyl)diresorcinol tetramethyl ether which was similarly oxidized to the related diquinone. This substance could not be converted into ardisiaquinone A because Thiele-Winter acetoxylation was accompanied by attack on the triple bond.However, 5,5'-(hexadecane-l,l6-diyl)diresorcinol dimethyl ether by successive oxidation, acetoxylation, hydrolysis and oxidation gave dihydroardisiaquinone A.