Depsidone synthesis. Part 19. Some β-orcinol depsidones

Abstract

The synthesis of the lichen depsidones 3,8-dihydroxy-1,4,6,9-tetramethyl-11-oxo-11H-dibenzo[b,e][1,4]-dioxepin-7-carboxylic acid (hypoprotocetraric acid)(4), 8-hydroxy-3-methoxy-1,4,6,9-tetramethyl-11-oxo-11H-dibenzo[b,e][1,4]dioxepin-7-carboxylic acid (O-methylhyprprotocetraric acid)(5), 4-formyl-3,8-dihydroxy-1,6,9-trimethyl-11-oxo-11H-dibenzo[b,e][1,4]dioxepin-7-carboxylic acid (virensic acid)(6), and 4-formyl-3,8-dihydroxy-9-hydroxymethyl-1,6-dimethyl-11-oxo-11H-dibenzo[b,e][1,4]dioxepin-7-carboxylic acid (protocetraric acid)(7) is described.