No abstract

The new depsides 3,5-dichloro-2′-O-methylnorstenosporic acid (4), 5-chloro-2′-O-methylanziaic acid (5) and 3,5-dichloro-2′-O-methylnorhyperlatolic acid (6) have been detected in the lichenLecanora lividocinerea and the structures of these metabolites have been established by unambiguous synthesis. In addition, the synthesis of the depside 3,5-dichloro-4-O-demethylplanaic acid (7) is described.

1,8-Dihydroxy-3,6-dimethoxy-9H-xanthen-9-one ( 1 ) has been isolated from a lichen for the first time and its structure verified by unambiguous synthesis.

The structure of simonyellin (5,9-dihydroxy-4-methoxy-7-methyl-1H,6H-naphtho[1,8-cd]pyran-1,6-dione), a naphthopyran from the lichen Simonyella variegata Steiner, has been established by X-ray structure analysis of a corresponding tetraacetate derivative. Crystals of simonyellin tetraacetate are triclinic, Pī, a 10.974(2), b 11.282(3), c 20.634(3)Ǻ, α 92.23(2)°, β 100.03(1)°, γ 117.80(2)°; Z 4. Refinement of 2754 data with I > 3σ(I) gave conventional R factors of 0.043 and 0.034.

The β-orcinol depsidone, conhypoprotocetraric acid (2), has been identified in the lichens Relicina cf. incongrua and Lecanora myriocarpoides. This new depsidone has been synthesized and characterized, and the biosynthetic implications are discussed.