SYNTHESIS OF BENZOFURANOID SYSTEMS .4. TOTAL SYNTHESIS OF CYPERAQUINONE AND CONICAQUINONE

The total synthesis of the novel naturally occurring benzodifuroquinones, cyperaquinone (1) and conicaquinone (2), starting from phloroglucinol is described. A comparison of synthetic and natural compounds confirmed the original structural assignments. The key intermediate in the synthesis was the 3-methylbenzofuran (21) which was prepared in high yield by an internal site-specific base- catalysed Ar1-5 cyclization of the acetonyloxy derivative (19). The method has also been applied to the syntheses of linear furocoumarins and dibenzofurans. © 1978 Australian Journal of Chemistry.