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Synthesis 2001(11): 1585-1610
DOI: 10.1055/s-2001-16753
REVIEW
© Georg Thieme Verlag Stuttgart · New York

Strategies for the Synthesis of Ellagitannins

Karamali Khanbabaee*a, Teunis van Reeb
a Fachbereich Chemie und Chemietechnik der Universität Paderborn, Warburger Straße 100, 33098 Paderborn, Germany
Fax: +49(5251)60-3245; e-Mail: kkh@chemie.uni-paderborn.de;
b Department of Chemistry, University of Venda, Private Bag X5050, Thohoyandou, 0950 Republic of South Africa
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Received 24 April 2001
Publikationsdatum:
12. August 2004 (online)

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Abstract

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.

  • 1 Introduction

  • 2 Synthesis of Ellagitannins

  • 2.1 Generating the Ellagitannin Biaryl Unit by the Coupling of two d-Glucopyranose-linked Galloyl Units

  • 2.1.1 Feldman’s Approach to the Total Synthesis of Ellagitannins

  • 2.1.1.1 Total Synthesis of Tellimagrandin I (16)

  • 2.1.1.2 Total Synthesis of Tellimagrandin II (2)

  • 2.1.1.3 Total Synthesis of Sanguiin H-5 (27)

  • 2.1.1.4 Total Synthesis of Pedunculagin (30)

  • 2.1.1.5 Total Synthesis of Coriariin A (37)

  • 2.1.2 Construction of Some Ellagitannin Systems According to O. R. Martin

  • 2.1.3 Intramolecular Coupling Attempts by Kita

  • 2.2 Generation of Ellagitannin Biaryl Units by Double Esterification of Hexahydroxydiphenic Acid Derivatives with Suitably Protected Diol Derivatives of d-Glucopyranose

  • 2.2.1 Synthesis of Trideca-O-methyl-α-pedunculagin (53)

  • 2.2.2 Synthesis of O-Permethyltellimagrandin I (58) and O-Permethyltellimagrandin II (66)

  • 2.2.2.1 Synthesis of O-Permethyltellimagrandin I (58)

  • 2.2.2.2 Synthesis of O-Permethyltellimagrandin II (66)

  • 2.2.3 Recent Approaches to Total Syntheses of Ellagitannins

  • 2.2.3.1 Total Synthesis of Strictinin (74)

  • 2.2.3.2 Synthesis of the Protected Ellagitannin ”Undeca-O-benzyllagerstanninn C Methyl Ester" (82); Construction of the
    d-Gluconic Acid Unit as Special Structural Element of the Lagerstannins A-C

  • 2.2.3.3 Total Syntheses of Gemin D (84) and Hippomanin A (85); Investigation of Phase-Transfer-Catalysed Monobenzylation Reactions

  • 2.2.3.4 Total Syntheses of Praecoxin B (109) and Pterocarinin C (110)

  • 2.2.3.5 First Total Synthesis of 4,6-Di-O-galloyl-2,3-O-(R)-hexahydroxydiphenoyl-d-glucopyranose (117) and Galloyl 4,6-di-O-galloyl-2,3-O-(R)-hexahydroxydiphenoyl-β-d-glucopyranose (116)

Key words

natural products - ellagitannins - atropisomerism - glycosides - stereoselective synthesis

134

Number AL-131 Aldrich Technical Information Bulletin.

142

Khanbabaee, K.; Lötzerich, K. Lecture and Poster: Synthese von Undeca-O-benzyllagerstannin C methylester, Symposium-Aktuelle Entwicklungen in der Naturstofforschung, 11. Irseer Naturstofftage der DECHEMA e.V., Irsee/Allgäu, Februar 1999 (see also Lit. 89).