Showing papers in "Journal of The Chemical Society-perkin Transactions 1 in 1983"

Synthesis of condensed tannins. Part 9. The condensation sequence of leucocyanidin with (+)-catechin and with the resultant procyanidins

Abstract: Molar equivalents of synthetic (2R,3S,4R or S)-leucocyanidin and (+)-catechin condense with exceptional rapidity at pH 5 under ambient conditions to give the all-trans-[4,8]- and [4,6]-bi-[(+)-catechins](procyanidins B3, B6) the all-trans-[4,8:4,8]- and [4,8:4,6]-tri-[(+)-catechins](procyanidin C2, and novel isomer), and the presumed all-trans-[4,8]-linked tetraflavanoid analogue in the proportions 10:1:12:1:3. The facility and sequence of these condensations correlate with the observed absence of leucocyanidins (flavan-3,3′,4,4′,5,7-hexaols) and also the dominance of related condensed tannins in plant extracts.

Tannis of Casuarina and Stachyurus species. Part 1. Structures of pendunculagin, casuarictin, strictinin, casuarinin, casuariin, and stachyurin

Abstract: Three novel C-glucosidic ellagitannins, casuarinin, casauriin, and stachyurin, and two additional new ellagitannins, casuarictin and strictinin, were isolated from the leaves of Casuarina stricta, and their structures elucidated on the basis of chemical and spectral evidence. Pedunculagin and tellimagrandin I were also isolated, and the structure having (S)-4,4′,5,5′,6,6′-hexahydroxydiphenoyl groups was established for pedunculagin. These seven ellagitannins isolated from C. stricta have been found also in Stachyurus praecox.

Thiyl free radicals: direct observations of electron transfer reactions with phenothiazines and ascorbate

Abstract: Absolute rate constants for the reaction of the thiyl radicals derived from cysteamine, cysteine, glutathione, penicillamine, and 2-mercaptopropionylglycine (Thiola) with the phenothiazines, promethazine and chlorpromazine and with ascorbate ion, have been measured by pulse radiolysis and have been found to lie in the range 0.03–1.3 × 109 I mol–1 s–1. The reactions are considered to occur by an electron transfer mechanism. The possibility that, in biochemical systems, glutathione can act as a catalyst linking hydrogen atom and electron transfer reactions is suggested.

Tannins and related compounds. Part 13. Isolation and structures of trimeric, tetrameric, and pentameric proanthicyanidins from cinnamon

Abstract: A proanthocyanidin trimer, two tetramers, and a pentamer have been isolated in their free phenolic forms from cinnamon, the bark of Cinnamomum zeylanicum(Lauraceae). Partial acid-catalysed degradation of these tannins with phenylmethanethiol, in conjunction with 1H- and 13C-n.m.r. analysis, has unequivocally established their structures as epicatechin-(4β→8, 2β→7) epicatechin-(4α→8)-epicatechin (5); epicatechin-(4β→8, 2β→7)-epicatechin-(4α→8)-epicatechin (6); epicatechin-(4β→6)-epicatechin-(4β→, 2β→7)-epicatechin-(4α→8)-epicatechin (7); and epicatechin-(4β→8)-epicatechin-(4β→8)epicatechin-(4β→8, 2β→7)-epicatechin-(4α→8)-epicatechin (8).

Arsenic-containing ribofuranosides: isolation from brown kelp Ecklonia radiata and nuclear magnetic resonance spectra

Abstract: 2-Hydroxy-3-sulphopropyl 5-deoxy-5-(dimethylarsinoyl)-β-ribofuranoside (1a) and 2,3-dihydroxypropyl 5-deoxy-5-(dimethylarsinoyl)-β-ribofuranoside (1b) have been isolated from the brown kelp Ecklonia radiata. Extraction of a second batch of Ecklonia yielded 3-‘glycerophosphoryl’-2-hydroxy-1-[5-deoxy-5-(dimethylarsinoyl)-β-ribofuranosyloxy] propane (1c) together with compound (1a). These compounds were identified chiefly by n.m.r. spectroscopy. N.m.r. data for the related (2S)-3-[5-deoxy-5-(dimethylarsinoyl)-β-D-ribofuranosyloxy]-2-hydroxypropyl hydrogen sulphate (1d), extracted [together with compound (1b)] from the giant clam Tridacna maxima, are presented also.

The construction and use of potential–pH diagrams in organic oxidation–reduction reactions

Abstract: Potential–pH diagrams were constructed from literature data for phenol, 2,4,6-tri-t-butylphenol, and hydroquinone (1,4-dihydroxybenzene). The relationship between chemical and electrochemical phenomena is described, and the significance of the results of chemical experiments discussed in relation to the potential–pH diagrams for the case of phenol oxidations.

Metabolites of the higher fungi. Part 21. 3-Methyl-3, 4-dihydroisocoumarins and related compounds from the ascomycete family Xylariaceae

Abstract: Culture solutions of members of the ascomycete family Xylariaceae produce a series of 5-substituted 8-hydroxy-3-methyl-3,4-dihydroisocoumarins as major metabolites. Ramulosin, iso-ochracein, and mellein are produced by three Hypoxylon species and 4-hydroxy iso-ochracein by one species. The antibiotic pyrenophorin is produced by Nummularia broomeiana. The synthesis of 7-formylmellein from mellein is described and the products from the alkaline rearrangement of 5-formylmellein are studied spectroscopically.

Tremorgenic mycotoxins from Penicillium crustosum: isolation of penitrems A–F and the structure elucidation and absolute configuration of penitrem A

Abstract: The isolation and characteristics of six tremorgenic mycotoxins, penitrems A–F from cultures of Penicillium crustosum are reported. The assignment of structure (2) to penitrem A is based on a detailed study of its high-field 1H and 13C n.m.r. spectra. The conformation and relative configuration of penitrem A was deduced from the observed proton–proton nuclear Overhauser effects (n.O.e.) and the magnitude of the proton–proton coupling constants. The chirality of C-25 was determined as S by the ‘partial resolution’ method of Horeau and penitrem A must therefore have the (12R, 14S, 15R, 18S, 19R, 22S, 23S, 24R, 25S, 26R, 28S, 31R, 32S) absolute configuration.

Tremorgenic mycotoxins from Penicillium crustosum. Biosynthesis of penitrem A

Abstract: The biosynthesis of penitrem A has been studied with both 13C- and 2H-labelled precursors, viz. [1-13C]-, [2-13C]-, [1,2-13C2]-, and [1-13C,2-2H3]-acetate, [2-13C]-, [2,3-13C2]-, [2-2H2]- and [5-2H2]-mevalonate. The results show that penitrem A is derived from tryptophan, which contributes the indole moiety of the metabolite, geranylgeranylpyrophosphate, and two isopentenylpyrophosphate units. A 1,2-bond migration, involving the 2,3-bond of a mevalonate unit, occurs in the course of the biosynthesis and results in the observation of a one-bond (C,C) coupling between two [1-13C]acetate-derived carbon atoms and between two [2-13C]acetate-derived carbon atoms. Analysis of the one-bond (C,C)coupling constants in [2-13C]acetate-derived penitrem A showed that [1,2-13C2]acetate was formed during the fermentation. Although loss of water from an hydroxyisopropyl group to form the isopropenyl function present in penitrem A should proceed with retention of the stereochemical integrity of the two methyl groups, isomerization of the double bond causes equal distribution of 13C label between C-36 and C-38 and precludes any stereochemical deductions.

Base catalysed rearrangements involving ylide intermediates. Part 15. The mechanism of the Stevens [1,2] rearrangement

Abstract: The Stevens [1,2] rearrangement of acyl-stabilised ammonium ylides has been investigated with regard to stereoselectivity, intramolecularity and the formation of products in addition to the [1,2] rearrangement product. A detailed study of the effects of reaction conditions upon the rearrangement of the ylide derived from the salt (13) has shown that the stereoselectivity (retention of the configuration of the chiral migrating group) and intramolecularity decrease as solvent viscosity decreases. The rearrangement of the salt (13) in water at 0 °C is essentially intramolecular with virtually complete retention of the configuration of the migrating group. These results, together with the isolation of products that can be rationalised on the basis of random free-radical coupling, indicate that the [1,2] rearrangement of acyl-stabilised ammonium ylides normally involves a radical pair mechanism.

The Diels–Alder route to drimane related sesquiterpenes; synthesis of cinnamolide, polygodial, isodrimeninol, drimenin and warburganal

Abstract: The stereospecific preparation of various 1-vinyl-2,6,6-trimethylcyclohex-1-enes (6) as potential diene precursors in the Diels–Alder reaction with dimethyl acetylenedicarboxylate have been investigated. The reaction of the parent diene (6a) with dimethyl acetylenedicarboxylate affords an adduct (18) in 94% yield. This species was reductively isomerised using 10% Pd/C/H2 and a mineral acid to give a trans-fused decalin diester (19). Reduction of (19) with lithium aluminium hydride afforded 1,4,4a,5,6,8,8a-octahydro-5,8,8a-trimethyl-1 β,4a α,8aβ-naphthalene-1,2-dimethanol (24) a key starting material for the highly efficient syntheses of five drimane sesquiterpene natural products, cinnamolide (1), polygodial (2), isodrimeninol (3), drimenin (4), and warburganal (5). Microbial oxidation reactions using C. elegans or A. niger of (2), (24), and (1) gave good yields of the corresponding 3β-hydroxy derivatives, (30), (31), and (32). Several other unusually substituted drimane derivatives are reported.

Alkenylation of 1-acylindoles with olefins bearing electron-withdrawing substituents and palladium acetate

Abstract: The oxidation of 1-(2,6-dichlorobenzoyl) indole with olefins, such as alkyl acrylates and acrylonitrile, and palladium acetate resulted in selective 3-alkenylation of the indole nucleus. Treatment of 1-acyl-3-methyl-indoles under similar conditions gave the corresponding 2-alkenyl substituted indoles, while the oxidation of 6-oxo-6H-isoindolo[2,1-a]indole gave the corresponding 3-alkenyl substituted indoles.

The octanol–water partition coefficient of aromatic solutes: the effect of electronic interactions, alkyl chains, hydrogen bonds, and ortho-substitution

Abstract: The calculation from structure of the hydrophobic parameter, log P(octanol–water), involves the addition of fragment values (or of π constants to parent log P) plus correction factors for interactions not present in the standard state from which the f or π values were determined. In this paper the important correction factors for multply substituted aromatic solutes are classified as: electronic, negative ortho, hydrogen bonding, and alkyl–aryl. The electronic factor Fσ is best treated as a continuous function in a manner similar to Hammett's ρσ product. Both field and resonance components appear to be present in the electronic effect. σ and ρ values for 50 substituents are reported in a generalized structural form which makes possible estimation of many others. While the other factors F0,FHB, and Fαφ are probably continuous functions also, they are conveniently treated as ‘quantized’. Calculated in this way, the standard deviation for nearly 400 solutes amounts to less than twice the estimated error in their measurement, and thus a more precise estimation of these effects is unwarranted at this time. The overall equation is: observed log P= additive log P+ρσ– 0.29F0+ 0.63FHB– 0.15Fαφ.

Synthesis and conformation of procyanidin diastereoisomers

Abstract: The four theoretically possible diastereoisomeric 4 → 8 linked procyanidin dimers with two 2,3-cis-flavanoid units, epicatechin-(4β→ 8)-epicatechin (6), epicatechin-(4β→ 8)-ent-epicatechin (8), ent-epicatechin-(4α→ 8)-epicatechin (7), and ent-epicatechin-(4α→ 8)-ent-epicatechin (2), have been synthesized together with the 2,3-trans diastereoisomers catechin-(4α→ 8)-catechin (14) and catechin-(4α→ 8)-ent-catechin (15). The preferred rotamer conformations of the deca-acetate derivatives of (6), (8), (14), and (15) in chloroform were deduced from their 13C n.m.r. and high-field 1H n.m.r. spectra. The 1H n.m.r. spectra of the preferred conformers of the pairs of acetate derivatives of (6) and (15), and (8) and (14), were qualitatively similar as the relative configuration about the interflavanoid bond of one pair has a meso-relationship to the other.

Addition and cycloaddition reactions of the electrophilic vinyl nitroso compounds 3-nitrosobut-3-en-2-one, 2-nitrosopropenal, and ethyl 2-nitrosopropenoate

Abstract: 1-Chlorobutane-2,3-dione 2-oxime (2a) reacts with sodium carbonate and, in the presence of olefins, gives the oxazines (4) stereoselectively and in good yield. 3-Nitrosobut-3-en-2-one (1a) is postulated to be the intermediate in these reactions. Similar additions occur with 3-chloro-2-hydroxyiminopropanal (2b) and with ethyl bromopyruvate 2-oxime (3), although the oxazines are generally formed in lower yield. Competition experiments using pairs of olefins indicate that the intermediate (1a) adds preferentially to electron-rich olefins.The vinyl nitroso intermediates (1) act as electrophiles towards indole; the products are the corresponding 3-alkylindoles (11). Analogous reactions are observed with pyrrole, 1-methylpyrrole, 1,3-dimethoxybenzene, and NN-dimethylaniline; with 3-methylindole, addition takes place at the 3-position to give the cycloadducts (12).3-Nitrosopent-3-en-2-one (19) has been generated from 4-chloropentane-2,3-dione 3-oxime. This vinyl nitroso intermediate also undergoes cycloaddition to olefins, in competition with a hydrogen shift from the terminal methyl group which leads to isomerisation to pent-2-ene-2,3-dione 3-oxime (20).

Molecular inclusion in functionalized macrocycles. Part 6. The crystal and molecular structures of the calix[4]arene from p-(1,1,3,3-tetramethylbutyl)phenol and its 1 : 1 complex with toluene

Abstract: The cyclic tetramer (1a) isolated from the reaction mixture of the base-catalysed reaction of p-(1,1,3,3-tetramethylbutyl)phenol and formaldehyde crystallizes from acetone without including the solvent whereas in the presence of toluene a 1 : 1 complex between (1a) and toluene is formed. Crystals of the empty phase are monoclinic, space group P21/a, a= 12.753(8), b= 38.778(16), c= 11.370(7)A, β= 101.98(9)°, Z= 4, final R value 0.092; the toluene complex is orthorhombic, space group Fmm2, a= 21.227(16), b= 21.227(17), c= 14.522(14)A, Z= 4, final R value 0.069. The macrocycle exists in the cone conformation both in the empty form and in the complex, where the guest molecule occupies intermolecular cavities of channel type in the host lattice.

Fluorescence and induced circular dichroism studies on host–guest complexation between γ-cyclodextrin and pyrene

Abstract: Host–guest complexation between γ-cyclodextrin (γ-CD, cyclo-octa-amylose) and pyrene has been studied in detail by fluorescene and induced circular dichroism (i.c.d.) spectra. γ-CD forms complexes with pyrene with 1 : 1, 1 : 2, 2 : 1, and 2 : 2 stoicheiometries at ambient temperature. The inclusion of pyrene by γ-CD proceeds stepwise; γ-CD including only one pyrene molecule can accommodate a second pyrene molecule to produce a 1 : 2 and/or 2 : 2 complex. Both in a monomolecularly dispersed pyrene solution and in a suspended pyrene solution, several hours are required for γ-CD to include two pyrene molecules. The configuration of two pyrenes included is an S-helix. At temperatures above ca. 85 °C, a 1 : 1 complex alone is formed mainly, where a pyrene molecule is accommodated with its long axis parallel to the axis of γ-CD. The data are compared with those of the systems containing β-CD (cyclohepta-amylose) in place of γ-CD.

1 H and 2H nuclear magnetic resonance determination of the enantiomeric purity and absolute configuration of α-deuteriated primary carboxylic acids, alcohols, and amines

Abstract: The enantiomeric composition and absolute configuration of α-deuteriated primary carboxylic acids may be accurately determined by 1H and 2H nuclear magnetic resonance analysis of the corresponding esters of (S)-methyl 2-hydroxy-2-phenylethanoate (2). Similar methods with (S)-2-acetoxy-2-phenylethanoic acid (3) and (–)-camphanoyl chloride (1) as chiral reagents have enabled the enantiomeric purity of α-deuteriated primary alcohols and primary amines to be assayed. These chiral reagents may also be used to determine the enantiomeric composition of chiral secondary acids, alcohols, and amines.

Asymmetric synthesis using chirally modified borohydrides. Part 1. Enantioselective reduction of aromatic ketones with the reagent prepared from borane and (S)-valinol

Abstract: The asymmetric reduction of aromatic ketones with the reagents prepared from borane and chiral aminoalcohols was studied under various conditions. The ratio of borane to (S)-valinol was found to be optimum at 2–3:1, when up to 65–73% selectivity was obtained in the reduction of n-propyl phenyl ketone. The amino-alkoxy-amine-boranes (2) and/or (3) were tentatively proposed as the reaction species responsible for asymmetric induction.

Both-faces hindered porphyrins. Part 1. Synthesis and characterization of basket-handle porphyrins and their iron complexes

Abstract: The synthesis of the ‘both-faces’ hindered porphyrins using two different methods is reported. These so-called ‘basket-handle’ porphyrins (BHP) are derived from 5,10,15,20-tetraphenylporphyrin in which two opposite phenyl groups are bridged by alkylene or arylene-p-bisalkylene chains. In addition to the desired compounds [the cross-trans-linked isomer (7)], two other isomers were obtained [adjacent-trans-linked (8) and adjacent-cis-linked (9)]. These were separated by t.l.c. on silica gel and then individually characterized. The structural assignment of the three isomers in the five series studied was based on the 1H n.m.r. spectra of the free bases and of their iron(II) complexes.

Asymmetric reduction of cyclic imines with chiral sodium acyloxyborohydrides

Abstract: Asymmetric reduction of prochiral cyclic imines with chiral sodium acyloxyborohydrides (5a–i), which are easily prepared by the reaction of NaBH4 with various N-acyl α-amino-acids, has been investigated. Of these new reducing agents, triacyloxyborohydrides (5c–f), derived from NaBH4(1 equiv.) and (S)-N-acylproline (3 equiv.), were found to reduce 3,4-dihydropapaverine (2) in tetrahydrofuran to (S)-norlaudanosine (3) hydrochloride in 60% optical yield. The N-benzyloxycarbonyl derivative (5c) could be isolated as a powder and characterized. The effect of solvents on this asymmetric reduction has been examined by the use of the isolated reagent (5c); halogenated alkane solvents such as CH2Cl2 or CHCl2CH3 gave a better optical yield of compound (3)(70% e.e.). The reagent (5c) also reduced other cyclic imines (6a–c) and (8) to the corresponding alkaloids (7a–c) and (9) in excellent optical yields (70–86% e.e.), providing an effective route to the asymmetric synthesis of these alkaloids. A possible reaction path for this reduction is also presented.

Kijanimicin. Part 3. Structure and absolute stereochemistry of kijanimicin

Abstract: Kijanimicin, a novel antibiotic from Actinomadura kijaniata nov. sp. SCC1256 (ATCC 31588), has been shown by chemical degradation, spectroscopic studies, and X-ray crystallographic studies to have a unique tetronic acid structure. The molecule contains a branched chain tetrasaccharide moiety consisting of three units of 2,6-dideoxy-α-L-ribo-hexopyranose and one unit of 2,6-dideoxy-4-O-methyl-β-L-ribo-hexopyranose. The molecule also contains a novel nitrosugar, namely 2,3,4,6-tetradeoxy-4-methoxy-carbonylamino-3-C-methyl-3-nitro-β-D-xylo-hexopyranose (D-kijanose), which is the third nitrosugar to be isolated from an antibiotic. The structure of L-rubranitrose is revised to D-rubranitrose. Evidence for the total structure, the absolute stereochemistry, and the solution conformation of kijanimicin is presented.

Minor and trace sterols in marine invertebrates. Part 35. Isolation and structure elucidation of seventy-four sterols from the sponge Axinella cannabina

Abstract: Seventy-four 3β-hydroxy-sterols, of which twenty-four are new, with seven different nuclei [Δ5,7,9(11), Δ5,7, Δ8, Δ7, Δ5, 5α-saturated; and 5α-methoxy-Δ6,8(14)], and with eighteen different C7–C10-side chains, have been isolated by reverse-phase h.p.l.c. and argentic t.l.c. from the marine sponge Axinella cannabina. Characterization was accomplished by g.l.c.–m.s., high-resolution m.s., and 360-MHz 1H n.m.r. and u.v. spectroscopy.

Synthesis of some new tetra-arylporphyrins for studies in solar energy conversion

Abstract: The synthesis of tetra-arylporphyrins, for studies in solar energy conversion, is described. They are derived from 5,10,15,20-meso-tetrakis(4-hydroxyphenyl)porphyrin (4) which, in basic media, forms a green intermediate that is probably the tetraphenoxide (6). The porphyrins (10) and (13), were synthesised as prospective sensitisers for catalysed microheterogenous water photo-oxidation. U.v./visible spectroscopy demonstrates that the porphyrin (10) aggregates in aqueous solution. Cyclic voltammetry shows that the porphyrin (13) behaves as a typical viologen with bulky substituents. A pentameric porphyrin (15) was synthesised and characterised in order to model energy transfer in photosynthetic chlorophyll antennae. There is some evidence that weak singlet-energy transfer occurs between the porphyrin sub-units of the pentamer.

Synthesis of 5′-alkylthio-5′-deoxynucleosides from nucleosides in a one-pot reaction

Abstract: 5′-Alkyl (aryl) thio-5′-deoxynucleosides [alkyl (aryl) nucleoside sulphides] were prepared in high yields by the reaction of nucleosides with dialkyl or diaryl disulphides in the presence of tri-n-butylphosphine. The method is widely applicable to the synthesis of unsymmetrical sulphides.

Cardenolide glycosides of the asclepiadaceae. New glycosides from asclepias fruticosa and the stereochemistry of uscharin, voruscharin and calotoxin

Abstract: Eight new cardenolide glycosides, 19-deoxyuscharin (1b), 4′β-hydroxygomphoside (1k), 3′-didehydrogomphoside (1d), 3′-epigomphoside (1e), 3′-epiafroside (2e), 3′-epigomphoside 3′-acetate (1f), 3′-didehydroafroside (2d), and 3′-epiafroside 3′-acetate (2f), have been isolated from Asclepias fruticosa R. Br. The structures of all new compounds were established by spectral comparisons with known compounds. The chirality at C-3′ of uscharin (3b), voruscharin, and 19-deoxyuscharin (1b) is proposed to be S. By comparison with 4′β-hydroxygomphoside (1k), the β configuration of the 4′-hydroxy group of calotoxin (3k)(from Calotropis procera) has been established.

Synthesis of 5H-furo[3′,2′ : 6,7][1]benzopyrano[3,4-c]pyridin-5-ones and 8H-pyrano[3′,2′ : 5,6]benzofuro[3,2-c]pyridin-8-ones (pyridopsoralens)

Abstract: 5H-Furo[3′,2′ : 6,7][1]benzopyrano[3,4-c]pyridin-5-ones (pyrido[3,4-c]psoralens)(3) have been obtained by the von Pechmann reaction starting from 6-hydroxy-2,3-dihydrobenzofuran acetates plus 1-benzyl-3-ethoxycarbonylpiperidin-4-one and subsequent dehydrogenation. The synthesis of their 8H-pyrano[3′,2′ : 5,6]benzofuro[3,2-c]pyridin-8-one isomers (14) and (17) was achieved by two ways using: (i) ring closure of 4-formyl-3-hydroxy-2-methylbenzofuro[3,2-c]pyridine, and (ii) cyclisation of piperidinone O-(4,7-dimethylcoumarin-7-yl) oxime derivatives and aromatization.

The disulphide group in organic compounds: conformational dependence of core and valence sulphur electronic levels by X-ray photoelectron spectroscopy

Abstract: An X-ray photoelectron spectroscopic study is reported on symmetric acyclic aliphatic disulphides and cyclic or acyclic aromatic disulphides. Core-level binding energies and sulphur lone-pair peculiarities (energy splitting, binding energy, and peak intensity) provide detailed information on the conformation of the C–S–S–C entity (C–S and S–S bond lengths, CSS/SSC dihedral angle). These relations are then applied in cases where crystallographic data are not available (di-n-butyl disulphide, di-n-hexyl disulphide, and 2,2′-dinaphthyl disulphide).

Tannins and related compounds. Part 9. Isolation and characterization of polygalloylglucoses from Turkish galls (Quercus infectoria)

Abstract: Two structural isomers of pentagalloylglucose and four isomers of hexagalloylglucose have been isolated from Turkish galls (Quercus infectoria), in addition to 1,2,3,6-tetra-O-galloyl-β-D-glucose (2), and their structures were established on the basis of 13C n.m.r. analysis, methanolysis, and partial hydrolysis. Trihepta-, and octa-galloylglucoses were partially purified, and their structures were also characterized mainly by 13C n.m.r. spectroscopy. From the isolation and structural studies of these galloylglucoses Turkish gallotannin has been shown to be a mixture of two types of polygalloylglucoses; one type has a 1,2,3,6-tetra-O-galloyl-β-D-glucose core with depside galloyl group(s) at the C-2 and/or C-6 position of the glucose moiety, and the other has a 1,2,3,4,6-penta-O-galloyl-β-D-glucose core with depside galloyl group(s) randomly distributed at the C-2, -3, -4, and -6 positions. H.p.l.c. analysis showed that Turkish gallotannin has an average molecular weight of 1 032 and the composition ranges from trito nona-galloylglucoses.