Extractives from Guttiferae. Part XVI. Biogenetic-type synthesis of xanthones from their benzophenone precursors

Abstract

A general synthesis of polyhydroxybenzophenones is described. 2,3′,4′,6-Tetrahydroxy- 2,2′,3′,6-tetrahydroxy-, and 2,3,3′,4′,6-pentahydroxybenzophenones were prepared and oxidised to 1,6,7-trihydroxy-, 1,2,8-trihydroxy-, and 1,2,6,7-(or 1,4,6,7-) tetrahydroxyxanthones, respectively, by oxidative coupling.