Extractives from Guttiferae. Part XIX. The isolation and structure of two benzophenones, six xanthones and two biflavonoids from the heartwood of Allanblackia floribunda Oliver

Abstract

Ten metabolites, hydrocotoin (2-hydroxy-4,6-dimethoxybenzophenone), 2,3′-dihydroxy-4,6-dimethoxybenzophenone, 1,3,5-trihydroxyxanthone, 4′,5′-dihydro-1,6,7-trihydroxy-4′,4′,5′-trimethylfurano(2′,3′ : 3,4)xanthone, volkensiflavone, morelloflavone; and from methylation of the crude extracts, 1,7-dimethoxyxanthone, 1-hydroxy-5-methoxyxanthone, 1-hydroxy-3,7-dimethoxy-2-(3,3-dimethylallyl)xanthone, and 1,3,6,7-tetramethoxyxanthone have been isolated from the heartwood of Allanblackia floribunda Oliver. The biogenetic significance of the co-occurrence of these compounds is discussed and syntheses of hydrocotoin, methylhydrocotoin, and 2,3′,4,6-tetramethoxybenzophenone are described.