Results 171 to 180 of about 1,268 (204)

Depsidone synthesis. IV. Caloploicin

Australian Journal of Chemistry, 1976
The synthesis of the lichen depsidone caloploicin (2,4,7-trichloro-3-hydroxy-8-methoxy-1,6,9- trimethyldibenzo[b,e][l,4]dioxepin-11-one) (1) by oxidative coupling of 5'-chloro-2,2',4-trihydroxy-4- methoxy-3',6,6'-trimethylbenzophenone (23), and subsequent steps, is described.
MV Sargent, P Vogel
openaire   +1 more source

Depsidones from Anomalographis madeirensis

Biochemical Systematics and Ecology, 1999
0 ...
González, Antonio G., Hernández, Consuelo, Rodríguez, Elsa M., Del Carmen Alfayate, M., Bermejo, Jaime   +4 more
openaire   +2 more sources

Three New Lichen Depsidones

Australian Journal of Chemistry, 1987
The depsidones a- acetylconstictic acid (5-acetoxymethyl-1,4-dihydroxy-10-methoxy-8-methyl-3,7-dioxo-1,3-dihydro-7 H- isobenzofuro [4,5- b][l,4] benzodioxepin-ll-carbaldehyde ) (6), substictic acid (1,4-dihydroxy-10-methoxy-8-methy1-3,7-dioxo- 1,3-dihydro-7 H- isobenzofuro [4,5-b][1,4]benzodioxepin-11-carbaldehyde) (7) and conphysodalic acid (9 ...
JA Elix, KL Gaul, PW James, OW Purvis
openaire   +1 more source

ChemInform Abstract: DEPSIDONE SYNTHESIS. PART 16. BENZOPHENONE‐GRISA‐3′,5′‐DIENE‐2′,3‐DIONE‐DEPSIDONE INTERCONVERSION: A NEW THEORY OF DEPSIDONE BIOSYNTHESIS

Chemischer Informationsdienst, 1981
AbstractOxidative Kupplung der substituierten 2,2′‐Dihydroxy‐4‐methoxy‐benzophenone (I), (IV) bzw. (VII) mit K3 [Fe(CN)6] unter optimalen Bedingungen liefert die Grisadiendione (II), (V) bzw. (VIII), die sich bei Thermolyse in fester Form oder in Lösungsmitteln wie TFA/ CHz C12, Diphenylether oder Phenetol in die Depsidone (III), (VI) bzw.
T. SALA, M. V. SARGENT
openaire   +1 more source

Depsidone synthesis. III. Grayanic acid

Australian Journal of Chemistry, 1976
The structure of the lichen depsidone grayanic acid (1) (6-heptyl-8-hydroxy-3-methoxy-1-methyl-11- oxo-11 H -dibenzo[b,e][1,4]dioxepin-7-carboxylic acid) proposed by Shibata and Chiang was confirmed by the synthesis firstly of methyl O -methylgrayanate (19), and then of grayanic acid itself. The key step in both syntheses was an Ullmann reaction.
P Djura, MV Sargent
openaire   +1 more source

Antioxidant activity of depsides and depsidones

Phytochemistry, 1994
The antioxidant activity of lichenic metabolites, depsides and depsidones, was assessed by their effects as inhibitors of rat brain homogenate auto-oxidation and beta-carotene oxidation. The results obtained in both systems indicate that lichenic metabolites afford a moderate protection in the microM concentration range. The largest effect was measured
M E, Hidalgo, E, Fernández, W, Quilhot, E, Lissi   +3 more
openaire   +2 more sources

Two New Depsidones from Parmelia saxatilis

Chemistry of Natural Compounds, 2021
Two new depsidones, diffractione B (1) and salazinin A (2), and two known compounds, the dibenzofuran derivative usnic acid (3) and depsidone salazinic acid (4), were isolated from Parmelia saxatilis. The structures of the isolated compounds were identified by spectral analysis and comparison with literature data.
null Xigurigan, null Tunuomula, null Haliga, Shu Zhen Bai, null Ganchimeg, null Qirigeer, Li Guo Yang, Laxinamujila Bai   +7 more
openaire   +1 more source

Depsidone synthesis. Part 16. Benzophenone–grisa-3′,5′-diene-2′,3-dione–depsidone interconversion: a new theory of depsidone biosynthesis

J. Chem. Soc., Perkin Trans. 1, 1981
The synthesis of a number of grisa-3′,5′-diene-2′,3-diones by oxidative coupling of substituted 2,2′-dihydroxy-4-methoxybenzophenones is described. The rearrangement of these grisadienediones to depsidones under basic, acidic, and thermal conditions is described and the mechanisms of these reactions are discussed.
Tony Sala, Melvyn V. Sargent
openaire   +1 more source

Depsidones from the Endophytic Fungus BCC 8616

Journal of Natural Products, 2006
Three new depsidones (1-3) have been isolated from the endophytic fungus BCC 8616 and their structures analyzed on the basis of spectroscopic data interpretation. Compound 1 exhibited weak cytotoxic activity against breast and epidermoid carcinoma cell lines.
Pattama, Pittayakhajonwut, Aibrohim, Dramae, Siribhorn, Madla, Nattapat, Lartpornmatulee, Nattawut, Boonyuen, Morakot, Tanticharoen   +5 more
openaire   +2 more sources

New depsidones from Lobaria oregana

Phytochemistry, 1980
Abstract From the lichen, Lobaria oregana , two new minor metabolises, methylstictic acid ( 4 ) and cryptostictic acid ( 5 ) were isolated. The structures of 4 and 5 were elucidated by 1 H NMR and MS analysis.
Sachiko Shimada (née Miyoshi), Tamotsu Saitoh, Ushio Sankawa, Shoji Shibata   +3 more
openaire   +1 more source