Extractives from Guttiferae. Part XXV. Synthesis of the natural 1,5-dioxygenated xanthones, dehydrocycloguanandin, guanandin, isoguanandin, and 5-hydroxy-1-methoxyxanthone
Abstract
Total syntheses of the natural metabolites dehydrocycloguanandin, guanandin, isoguanandin, and 5-hydroxy-1-methoxyxanthone are described. These involved a modified synthesis of 1,5-dihydroxyxanthone from 2-hydroxy-2′,3,6′-trimethoxybenzophenone and appropriate methylation, isoprenylation, and Claisen rearrangements.