Ellagitannin chemistry. The first example of biomimetic diastereoselective oxidative coupling of a glucose-derived digalloyl substrate

Feldman, Ken S.; Ensel, Susan M.

doi:10.1021/ja00056a058

Cited by 26 publications

(8 citation statements)

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“…First, gallic acid derivatives are esterified with different derivatives of D-glucopyranose. Utilising the template effect of the chiral D-glucopyranose, the 2,3-or 4,6-galloyl units are then coupled diastereoselectively, using different reagents, to form the (S)-biaryl unit (Sections 2.1.1, [62][63][64]68,69 2.1.2, 70 and 2.1.3 71 ).…”

Section: Galloyl Unitsmentioning

confidence: 99%

“…75 The calculations showed a significant energy difference between the different final products, which seems to be the main reason for the observed diastereoselectivity. [62][63][64]68,69 2.1.1.1 Total Synthesis of Tellimagrandin I (16) With the total synthesis of tellimagrandin I (16) 62 Feldman was able to prepare the first representative of the ellagitannin class. Feldman's strategy for the construction of an (S)-HHDP unit has as its key step the biomimetic, oxidative biaryl coupling of neighboring galloyl groups by means of Pb(OAc) 4 .…”

Section: Biographical Sketchesmentioning

confidence: 99%

“…An alternative way of generating the ellagitannin biaryl units is provided by the direct double esterification of hexahydroxydiphenic acid derivatives with different diol derivatives of D-glucopyranose. Compared to the first method, this method has several advantages: 1) There is no need for the selective functionalization of the phenolic hydroxyl groups in gallic acid; 2) similarly, the selective desilylation needed for the coupling step in the first method, is unnecessary; 3) the coupling step for the formation of the chiral biaryl unit, which in the first method usually results in the formation of regioisomer mixtures that are difficult to separate by chromatography, [62][63][64]68,69 is unnecessary; 4) the second method can be used to synthesize both R-and S-configured 2,3-(HHDP)-ellagitannins, which is impossible applying the first method. 67,80,81 In the second method there are different ways to access the hexahydroxydiphenic acid derivatives.…”

Section: Generation Of Ellagitannin Biaryl Units By Double Esterificamentioning

confidence: 99%

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Strategies for the Synthesis of Ellagitannins

Khanbabaee¹,

Ree²

2001

Synthesis

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As a result of recent insights in the molecular structures and medicinal uses of the tannins, this class of natural products has enjoyed renewed scientific interest. This is reflected on the one hand in the enormously increased number of publications reporting on the isolation, characterization and biological activity of the tannins, and on the other hand in the steadily growing number of papers reporting tannin syntheses. In this review the most recent advances in the total synthesis of ellagitannins are discussed. In nature the ellagitannins occur usually only as the R-or only as the S-configured atropisomer, while the corresponding opposite atropisomers are seldom found. The configuration of the hexahydroxydiphenoyl units (HHDP's) found in ellagitannins is usually determined by the linkage position of the HHDP's with the polyol residues of the ellagitannins. Those ellagitannins of which the HHDP's are linked to the 2,3-or 4,6-positions of D-glucopyranose, have the S configuration; the corresponding 3,6-(HHDP)-ellagitannins are R-configured. Very few exceptions exist where both atropisomers are known. With one atropisomer showing the "normal" configuration, the other atropisomer is usually indicated in the literature as "unusual ellagitannin". This observed strict atropodiastereoselectivity in the biosynthesis of normally configured and unusual ellagitannins has led to the formulation of several hypotheses, which will be examined, in addition to the overview of effective concepts and strategies for the synthesis of ellagitannins.

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Section: Galloyl Unitsmentioning

confidence: 99%

Section: Biographical Sketchesmentioning

confidence: 99%

Section: Generation Of Ellagitannin Biaryl Units By Double Esterificamentioning

confidence: 99%

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Strategies for the Synthesis of Ellagitannins

Khanbabaee¹,

Ree²

2001

Synthesis

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“…The synthesis of a model system 164 (Scheme 40), combined with molecular modeling studies on a simplified model of the digalloyl coupling precursor 163 (e.g. 163a), provided results consistent with this postulate [78,116]. It is worth noting that in this example the coupling is not regioselective (with no consequence for Scheme 39.…”

Section: Transfer Of Chiral Information Via the Molecular Backbonementioning

confidence: 54%

Oxidative Aryl‐Coupling Reactions in Synthesis

Lessène

Feldman

2002

Modern Arene Chemistry

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The oxidant-mediated coupling of electron-rich arene rings has served over several decades as a valuable procedure to access biaryl units. The complex mixtures of isomers that often plagued the earliest studies have gradually given way to synthetically useful product distributions upon application of more selective coupling protocols. Continual advances in the nature of the oxidant (and its attendant ligands) and more precisely defined reaction conditions have led to increasing levels of control upon CaC bond formation. Chemoselective (CaC vs. CaO bond formation with phenols; suppression of product oxidation), regioselective (o-o 0 , vs. o-p 0 vs. p-p 0 CaC bond formation), and, more recently, stereoselective (atropisomer-selective) biaryl bond formation can now be achieved in many well-defined systems. A survey of the more recent advances in these areas is presented.14.1

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“…The pioneering method for synthesizing the HHDP group is Feldman's coupling (Scheme 1, a) [24][25][26]. They coupled diphenylmethylene-protected gallates 15 oxidatively using Pb(OAc) 4 .…”

Section: Synthesis Of the Hhdp Groupmentioning

confidence: 99%

Fundamental Methods in Ellagitannin Synthesis

Yamada

Hirokane

Ikeuchi

et al. 2017

Natural Product Communications

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This account describes methods for synthesizing natural ellagitannins. The ellagitannins, a class of polyphenols, has a wide variety of chemical structures and biological activities. Here, we focus on three topics, which are the synthesis of the hexahydroxydiphenoyl group, construction of the hexahydroxydiphenoyl bridge, and synthesis of CO digallates. The hexahydroxydiphenoyl group and the CO digallates are CC and CO coupled galloyl groups, respectively, both group of which are the two major components of ellagitannins. By combining methods described in this account, many ellagitannins might be synthesized.

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Ellagitannin chemistry. The first example of biomimetic diastereoselective oxidative coupling of a glucose-derived digalloyl substrate

Cited by 26 publications

References 0 publications

Strategies for the Synthesis of Ellagitannins

Strategies for the Synthesis of Ellagitannins

Oxidative Aryl‐Coupling Reactions in Synthesis

Fundamental Methods in Ellagitannin Synthesis

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