Lecideoidin and 3'-Dechlorolecideoidin, New Depsidones from an Australian Lecidea (Lichen)

Abstract

The depsidones lecideoidin (3',5-dichloro-2',4-dihydroxy-1'-methoxycarbonyl-6,6'-dimethyldepsidone) (3) and 3'-dechlorolecideoidin (5-chloro-2',4-dihydroxy-1'-methoxycarbonyl-6,6'-dimethyldepsidone)(4) have been isolated from an Australian Lecidea species. The structure of these compounds followed from the spectroscopic properties and by conversion of the former compound into the syntheticdepsidone, 3'-chloro-O-methylgangaleoidin (13).

New meta -depsidones and diphenyl ethers from the lichen Parmotrema tsavoense (Krog & Swinscow) Krog & Swinscow, Parmeliaceae

“…14.15 These type of observations were reported for some lichen diphenyl ethers. 16,17,18 With this point of view, the A-and B-rings of compound 6 were not coplanar and the consequence was methoxy protons of the methoxycarbonyl group of the A-ring and the methyl protons H 3 -8′ of the B-ring were in close proximity to each other to have the NOESY correlations as mentioned above. The comparison of chemical shift values of protons of the A-ring (H-5, CH=O, H 3 -9) of 6 with corresponding ones of depsidones 1 and 5, having the same partial structure and being measured in the same deuterated solvent ( Table 1) showed clearly that protons of the diphenyl ether 6 were up-field shifted (∆δ = 0.25−0.34) due to the ring current effect.…”

“…The known compounds were protocetraric acid (8), 3 8'-O-methylprotocetraric acid (9), methyl haematommate (10), 4 atranorin (11), 5 methyl β-orsellinate (12), 6 methyl orsellinate (13), 7 virensic acid (14), 8 zeorin (15), 9 2-Omethylatranol (16), 10 and (+)-prasorediosic acid (17). 11 The seven new compounds were elucidated as the following.…”

Brominated Depsidones from Acarospora gobiensis, a Lichen of Central Asia

“…2 Most of the known depsidones are lichen metabolites, and a few are chloro substituted. [3][4][5][6] The lichen Acarospora gobiensis H. Mogn. (Acarosporaceae) is a typical mountain species, colonizing rock substrates.…”

<p><strong>Notes on the circumscription of the lichens <em>Lecanora leprosa </em>and <em>L. sulphurescens </em>(Lecanoraceae, lichenised Ascomycotina)</strong></p>

“…Chlorolecideoidin was prepared by chlorination of lecideoidin (Chester et al 1979) with sulphuryl chloride as described above. The standardized chromatographic data for these compounds are listed in Table 1.…”