Depsidone synthesis. VI. Colensoic acid

Abstract

The synthesis of the lichen depsidone colensoic acid (1) (8-hydroxy-3-methoxy-11-oxo-1,6-dipentyl- 11H-dibenzo[b,e][l,4]dioxepin-7-carboxylic acid) by Ullmann reaction of benzyl-2-bromo-4-methoxy- 6-pentylbenzoate (18) and methyl 4,6-dibenzyloxy-3-hydroxy-2-pentylbenzoate (27) and subsequent steps is described.