The structure of galbinic acid. A depsidone from the lichen Usnea undulata

Abstract

The depsidone, galbinic acid (α-acetylsalazinic acid) (4), has been isolated from the lichen Usnea undulata together with usnic, norstictic and salazinic acids. The structure of the compound (4) followed from a combination of spectroscopic and chemical data and was confirmed by comparison with a synthetic sample. The acetylation of salazinic acid was further investigated.