Structure of the lichen depsidone gangaleoidin

Sargent, Melvyn V.; Vogel, P.; Elix, John A.

doi:10.1039/p19750001986

Cited by 18 publications

(12 citation statements)

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“…Given that this new compound was biosequentially related to these substances, Omethylgangaleoidin or chlorolecideoidin seemed the most likely possibilities. Chromatographic comparisons of extracts of these lichens with a synthetic sample of O-methylgangaldeoidin (Sargent et al 1975) established that this compound was dissimilar to the unknown lichen substance. Subsequently we have undertaken the synthesis of chlorolecideoidin and found that the TLC and HPLC behaviour of this compound to be identical with that of the minor, new metabolite present in these lichens.…”

Section: The New Substance: Chlorolecideoidinmentioning

confidence: 98%

Notes on the circumscription of the lichens Lecanora leprosa and L. sulphurescens (Lecanoraceae, lichenised Ascomycotina)

Lumbsch

Elix

1993

BDE

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Lecanora leprosa and L. sulphurescens are two commonly misidentified pantropical lichens. A detailed circumscription is presented to help overcome such difficulties. Both species contain a chemosyndrome of chlorodepsidones based on gangaleoidin. The new depsidone chlorolecideoidin (methyl 2,4,9-trichloro-3,8-dihydroxy-1,6-dimethyl-11-oxo-11H-dibenzo[b,e][1,4]-dioxepin- 7-carboxylate) has been shown to be a minor component of both species.

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Section: The New Substance: Chlorolecideoidinmentioning

confidence: 98%

Notes on the circumscription of the lichens Lecanora leprosa and L. sulphurescens (Lecanoraceae, lichenised Ascomycotina)

Lumbsch

Elix

1993

BDE

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“…(E) -4-(4-IsopropyZ-7-methyZbenzofu~an-2-yl) -3-methoxycarbonylbut-3-enoic Acid (29) .-The crude aldehyde (28) (1 1 .O g ) and 2-carboxy-1 -methox ycarbonylethyltriphenylphosphorane l8 (21.1 g) in dry T H F (130 ml) were stirred a t room temperature for 20 h. The solution was then poured into water and extracted with ethyl acetate. Acidic material was recovered with aqueous sodium hydrogen carbonate in the usual way.…”

Section: Photochemical Reaction Of 3-methoxy-5-methylphenylmentioning

confidence: 99%

“…For the synthesis of the benzofuran (28) we required the aldehyde (24) which had previously been synthesized by Duff.lg A better synthesis of salicylaldehydes is the recently reported method of Zwanenburg and Reynen.20 Consequently,carvacrol (21) was acylated with oxalyl chloride in the presence of 4-(NN-dimethylamino)pyridine in boiling chloroform and the intermediate was cyclized upon treatment with aluminium chloride. The resultant benzofurandione (22) was reduced with lithium aluminium hydride to the trio1 (23) which afforded the aldehyde (24) in high overall yield on periodate oxidation.…”

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confidence: 99%

Naturally occurring dibenzofurans. Part 1. A synthesis of cannabifuran

Sargent¹,

STRANSKY²

1982

J. Chem. Soc., Perkin Trans. 1

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The synthesis of dibenzofurans from diphenyl ethers by non-phenolic oxidative coupling, U.V. irradiation, and by reaction with palladium(ll) acetate has been investigated. 9-lsopropyl-6-methyl-3-pentyldibenzofuran-l-ol (cannabifuran) (35), a minor cannabis constituent, has been synthesized by annulation of 4-isopropyl-7-methylbenzofuran-2-carbaldehyde (28) by Wittig reaction with 2-carboxy-1 -methoxycarbonylethyltriphenylphosphorane and ring closure and functional-group modification of the resultant (€)-4-(4-isopropyl-7-methyIbenzofuran-2-yl)-3-methoxycarbonylbut-3-enoic acid (29).DIBENZOFURANS are comparatively rare natural products: nine are known to occur in lichens,132 and five have been isolated from higher plant^.^-^ We are interested in developing syntheses of some of these compounds since there is a dearth of good general synthetic methods available for dibenzofurans. The classical met hods of synthesis involve Pschorr cyclization of 2-phenoxyanilines,6 or cyclization of 2,2'-dihydroxybiphenyls or their methyl ethers under acidic condition^.^,^ Owing to the difficulty of preparation of many of these intermediates these methods are not easily adapted to the synthesis of the natural products. Some success has been achieved by Diels-Alder annulation of 2-vinylbenzofurans and by rearrangement of 3-(2-methylbenzofuran-3-yl)prop-l ,%dienones but these methods are of limited use.l0Non-phenolic oxidative coupling of suitably substituted diphenyl ethers appeared to be an attractive method for the synthesis of dibenzofurans. Consequently we prepared the diphenyl ethers (1) and (3) by conventional methods and attempted to convert them into dibenzofurans by treating them with vanadium trifluoride oxide l1 or thallium( 111) trifluoroacet ate l2 under a variety of conditions. In no case was any dibenzofuran detected. The diphenyl ether (4) was recovered unchanged from an attempted reaction with vanadium trifluoride oxide under conditions whereby the methyl phosphinate analogue undergoes smooth cyclization to the dibenzophosphole.13~tThe preparation of a number of alkyldibenzofurans by U.V. irradiation of diphenyl ethers in the presence of iodine has been reported.l* We investigated this method using the diphenyl ethers (1) and (3). In the first example poor yields of the isomeric dibenzofurans (5) and (7) were isolated. Their structures were deduced from their lH n.m.r. spectra. Similarly the diphenyl ether (3) gave the three possible products (9), (ll), and (12) in poor yield. Again their structures were deduced from their lH n.m.r. spectra. An attempt was made to convert the diphenyl ether (2), which contains an ester function as a blocking group, into the dibenzofuran (8). The only product which was isolated from this irradiation was the xanthone (13).It has been reported that diphenyl ether is converted t We thank Dr. A. Sierakowski for these experimental details.into dibenzofuran on treatment with palladium(I1) acetate in boiling acetic acid.15 We investigated this reaction for a number of diphenyl ethers but the ...

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“…D ies erfo rd e rt eine e n tsp re chende S chutzgruppenstrategie, ausgehend von leicht zugänglichem M ethylorsellinat 2 a [7].…”

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Verbesserte Synthese von Dichlorisoeverninsäure / Improved Synthesis of Dichloroisoeverninic Acid

Dornhagen

Scharf

1985

Zeitschrift Für Naturforschung B

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Structure of the lichen depsidone gangaleoidin

Cited by 18 publications

References 1 publication

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

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

Naturally occurring dibenzofurans. Part 1. A synthesis of cannabifuran

Verbesserte Synthese von Dichlorisoeverninsäure / Improved Synthesis of Dichloroisoeverninic Acid

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