The Synthesis of 1,8-Dihydroxy-2,3,4,6-tetramethoxyxanthone and 1,6-Dihydroxy-3,5,7,8-tetramethoxy-xanthone, a Confirmation of Structure

Aurell, M. J.; Gil, Salvador; Sanz, Vicente Claramonte; Tortajada, A.

doi:10.1021/np50064a032

Cited by 4 publications

(6 citation statements)

References 13 publications

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“…Both physical and spectral data of l,3-dihydroxy-2,8-dimethoxyxanthone [14] differed from those described for a naturally occurring xanthone isolated from K. candidissima (6). The data cited for the naturally occurring xanthone isolated from K. candidissima (6) are quite similar to those described for the dihydroxy-dimethoxyxanthone isolated from Ce.…”

Section: Resultsmentioning

confidence: 58%

“…Demethylations of 1,2,3,8-tetramethoxyxanthone [11] were performed with boron trichloride at different reaction times and concentrations of reagent. For short reaction time (0.5 h) (14) the main product (76%) was a monohydroxy-trimerhoxyxanthone (C16H1406) identified as l-hydroxy-2,3,8-trimethoxyxanthone [13] by the following evidence: the hydroxyl group must be placed at C-1 or C-8, because a signal is found at very low field in 'H nmr (8 13.12) due to chelation with the carbonyl group, and no hydroxyl band is observed in the ir spectrum due to the same chelation. Besides, uv maxima in MeOH show a strong bathochromic shift on addition of A1C13, which is not destroyed by HC1 (23,24).…”

Section: Resultsmentioning

confidence: 99%

“…With pipetidine-H20 (5:2) and 110 h of reflux (Table 4), a mixture of 1,3-dihydroxy-2,8-dimethoxyxanthone [14] (56%), along with l,3,8-trihydroxy-2methoxyxanthone [15] (38%), was obtained.…”

Section: Resultsmentioning

confidence: 99%

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Synthesis of 1,2,3,8-Tetraoxygenated Xanthones

Gil¹,

Palanca²,

Sanz³

et al. 1990

J. Nat. Prod.

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Section: Resultsmentioning

confidence: 58%

Section: Resultsmentioning

confidence: 99%

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Synthesis of 1,2,3,8-Tetraoxygenated Xanthones

Gil¹,

Palanca²,

Sanz³

et al. 1990

J. Nat. Prod.

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“…Our synthetic strategy (Scheme 1) based on our previous experience (7,10,11), consisted of the preparation of the appropriately substituted benzophenone, using TFAA as condensing agent (12), which was then cyclized to the corresponding xanthone. Benzyl ethers were used as the protective groups for all phenolic groups (13).…”

Section: Resultsmentioning

confidence: 99%

Synthesis of 1,3,4,8-Tetraoxygenated Xanthones

Gil¹,

Palanca²,

Sanz³

et al. 1991

J. Nat. Prod.

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Six 1,3,4,8-tetraoxygenated xanthones are synthesized. The possibility of a 1,3,4,8-tetraoxygenated pattern for two xanthones from Centaurium linarifolium is disproved. New structures are proposed for these two xanthones as 1,3,5-trihydroxy-2-methoxyxanthone, already cited in the literature, and 1,3-dihydroxy-2,5-dimethoxyxanthone, not previously cited.During the past 30 years, a large number of xanthones have been isolated from higher plants and their natural occurrence and synthesis have gained considerable importance (1). In addition, in several cases the medical properties of plants have been attributed to their xanthone constituents ^and several pharmacological studies have been done on them (2).Centaurium. linarifolium (Lamark) G. Beck (Gentianaceae), a plant commonly found in eastern Spain, has been used in folk medicine as a digestive, an antipyretic, and a blood circulation stimulant (3). Several new xanthones were isolated from this plant, and two alternative structural proposals were advanced on the basis of spectral data for two of them (4). These were 1,3,8-trihydroxy-2-methoxy-or 1,3,8-trihydroxy-4methoxyxanthone and 3,8-dihydroxy-1,2-dimethoxy-or 3,8-dihydroxy-1,4-dimethoxyxanthone.No naturally occurring 1,3,4,8-tetraoxygenated xanthones have been described before, although the synthesis of 1,4,8-trihydroxy-3-methoxy (5) and 1,3,4,8-tetramethoxyxanthone (6) has been described. In a previous report we have discarded the 1,2,3,8-tetraoxygenated pattern for the xanthones from Centaurium linarifolium (7), and in the present paper six 1,3,4,8-tetraoxygenated xanthones have been synthesized in order to confirm the alternative structures. A systematic study of their spectral data, summarized in Tables 1,2, and 3, will be very valuable in the assignment of the correct structures for new 1,3,4,8-tetraoxygenated xanthones.For unambiguous assignment of the 13C-nmr signals from unsubstituted carbon atoms, 1H-13C correlation experiments were performed. This allowed the assignment

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“…17 . The 1,3,4-Trimethoxy-6,7-methylenedioxyxanthone (isopolygalaxanthone-A) has been synthesized From 1,3-Dihydroxy-6,7-metltylenedioxyxanthone by hydroxylation with alkaline persulphate followed by methylation.…”

Section: Uses Of Plants Source Of Pentaoxygenated Hexaoxygenated Andmentioning

confidence: 99%

Naturally occurring pentaoxygenated, hexaoxygenated and dimeric xanthones: a literature survey

Peres

Nagem

1997

Quím. Nova

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This review gives information on the chemical study of 71 pentaoxygenated, 11 hexaoxygenated and 9 dimeric and more complex xanthones naturally occurring in 7 families, 29 genus and 62 species of higher plants, and 11 described as fern and fungal metabolites. The value of these groups of substances in the connection with the pharmacological activity and the therapeutic use of some species is shown. The structural formulas of 23 isolated compounds and their distribution in the species studied are given.

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The Synthesis of 1,8-Dihydroxy-2,3,4,6-tetramethoxyxanthone and 1,6-Dihydroxy-3,5,7,8-tetramethoxy-xanthone, a Confirmation of Structure

Cited by 4 publications

References 13 publications

Synthesis of 1,2,3,8-Tetraoxygenated Xanthones

Synthesis of 1,2,3,8-Tetraoxygenated Xanthones

Synthesis of 1,3,4,8-Tetraoxygenated Xanthones

Naturally occurring pentaoxygenated, hexaoxygenated and dimeric xanthones: a literature survey

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