- An efficient synthesis of procyanidins. Rare earth metal Lewis acid catalyzed equimolar condensation of catechin and epicatechin
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Stereoselective synthesis of catechin and epicatechin dimers under intermolecular condensation is achieved by an equimolar amount of coupling catalyzed by Yb(OTf)3. The coupled products were successfully converted to procyanidin B1, B2, B3, and B4.
- Mohri, Yoshihiro,Sagehashi, Masayoshi,Yamada, Taiji,Hattori, Yasunao,Morimura, Keiji,Kamo, Tsunashi,Hirota, Mitsuru,Makabe, Hidefumi
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Read Online
- From the gold-catalysed benzylation of arenes to the regio- and stereoselective synthesis of procyanidins dimers
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This work reports on a new intermolecular C-C coupling reaction between electron rich arenes and benzylic alcohols or ethers, catalysed by gold(III) salts, or other catalysts such as gold(I) and iron (III), and its application to the regio- and stereoselective synthesis of procyanidins dimers B1 and B3.
- Fabre, Sandy,Gueroux, Marie,Nunes, Emeline,Szlosek-Pinaud, Magali,Pianet, Isabelle,Fouquet, Eric
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p. 3045 - 3051
(2015/05/04)
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- Synthesis of procyanidin B1, B2, and B4 and their anti-inflammatory activity: The effect of 4-alkoxy group of catechin and/or epicatechin electrophiles for condensation
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Abstract: Procyanidin B1, B2, and B3 were synthesized based on a Yb(OTf)3 catalyzed equimolar condensation using methoxy and/or 4-(2-ethoxyethoxy) drivatives as electrophiles. The anti-inflammatory effect of synthetic procyanidin B1, B2, and B4 on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation of mouse ears was examined. Procyanidin B1, B2, B 4 suppressed TPA-induced inflammation of mouse ears by 48%, 34%, and 29%, respectively, at a dose of 200 μg. Their activities are stronger than those of indomethacin and glycyrrhetinic acid, the normally used antiinflammatory agent.
- Katoh,Oizumi,Mohri,Hirota,Makabe
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scheme or table
p. 233 - 238
(2012/07/28)
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- Preparation of dimeric procyanidins B1, B2, B5, and B7 from a polymeric procyanidin fraction of black chokeberry (Aronia melanocarpa)
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A semisynthetic approach has been used for the preparative formation of dimeric procyanidins B1, B2, B5, and B7. As starting material for the semisynthesis, polymeric procyanidins from black chokeberry were applied. These polymers were found to consist almost exclusively of (-)-epicatechin units. Under acidic conditions the interflavanoid linkages of the polymeric procyanidins are cleaved and the liberated (-)-epicatechin can react with nucleophiles, such as (+)-catechin or (-)-epicatechin. In this way, the polymeric procyanidins are degraded while dimeric procyanidins are formed. During this reaction only dimeric procyanidins are formed that contain (-)-epicatechin in the upper unit, that is, B1 [(-)-EC-4β→8-(+)-C)], B2 [(-)-EC-4β→8-(-)-EC], B5 [(-)-EC-4β→6-(-)-EC], and B7 [(-)-EC-4β→6-(+)-C]. The reaction mixtures of the semisynthesis can be successfully fractionated with high-speed countercurrent chromatography (HSCCC), and it is possible to isolate pure procyanidins B1, B2, B5, and B7 on a preparative scale.
- Esatbeyoglu, Tuba,Winterhalter, Peter
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experimental part
p. 5147 - 5153
(2011/07/29)
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- An efficient synthesis of procyanidins using equimolar condensation of catechin and/or epicatechin catalyzed by ytterbium triflate
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Stereoselective synthesis of catechin and epicatechin dimers under intermolecular condensation of equimolar amount of catechin derivatives catalyzed by Yb(OTf)3. The coupled products were successfully converted to procyanidins B1, B2, B3, and B4, respectively. Procyanidins B1, B2, B3, and B4 could be used as standard compounds for identifying the polyphenols in natural source.
- Mohri, Yoshihiro,Sagehashi, Masayoshi,Yamada, Taiji,Hattori, Yasunao,Morimura, Keiji,Hamauzu, Yasunori,Kamo, Tsunashi,Hirota, Mitsuru,Makabe, Hidefumi
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experimental part
p. 549 - 563
(2009/12/07)
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- Flavan-3-ols and procyanidins from the bark of Salix purpurea L.
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From a commercial aqueous ethanolic extract obtained from the bark of Salix purpurea L. the flavan-3-ols catechin, epicatechin, gallocatechin, catechin-3-O-(1-hydroxy-6-oxo-2-cyclohexene-1-carboxylic acid)-ester, the dimeric procyanidins B1, B3 and the trimeric procyanidins epicatechin- (4β→8)-catechin-(4α→8)-catechin and epicatechin- (4β→8)-epicatechin-(4β→8)-catechin were isolated. Structure elucidation was performed by NMR, CD, MS, degradation and optical rotation methods. A fraction containing higher oligomeric procyanidins was investigated by 13C NMR. Data indicate an average degree of oligomerization of 4 to 5 flavan-3-ol units with dihydroxylated B-rings and predominance of 2,3-cis-stereochemistry.
- Juergenliemk,Petereit,Nahrstedt, Adolf
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p. 231 - 234
(2008/02/02)
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- Scale-Up Syntheses of Two Naturally Occurring Procyanidins: (-)-Epicatechin-(4β,8)-(+)-catechin and (-)-Epicatechin-3-0-galloyl- (4β, 8)-(-)-epicatechin-3-0-gallate
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A scaleable process for the synthesis of two naturally occurring procyanidins, namely (-)-epicatechin-(4β,8)-(+)-catechin (1) and(-)-epiratechin-3-O-galloyl-(4β,8)-(-)-epicatechin-3-O-gallate (2), is described. The key steps were highlighted by improvements for the benzylation of (+)-catechin (3), stereo-selective reduction of the C-3 keto group of (2A)-5,7,3′,4′-tetrakis(benzyloxy)flavan-3-one (10), and coupling between 4-hydroxyethoxy-5,7,3′,4′-tetra-O-benzyl-(-)-epicatechin (11) and 5,7,3′,4′-tetra-O-benzyl-(+)-catechin (4) or 5,7,3′,4′-tetra-O-benzyl-(-)-epicatechin (6), respectively. The debenzylation performed in a biphasic system resulted in an improved yield and purity of the target compounds. The chemistry was scaled-up to produce multigram quantities of the title compounds (1 and 2) for various in vitro, ex vivo, and in vivo studies. Moreover, the scale-up process provided a detailed description for the preparation of multihundred to kilogram scale quantities of intermediates used in the synthesis of these two titled procyanidins.
- Sharma, Pradeep K.,Kolchinski, Alexander,Shea, Helene A.,Nair, Jayesh J.,Gou, Yanni,Romanczyk Jr., Leo J.,Schmitz, Harold H.
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p. 422 - 430
(2012/12/31)
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- An improved synthesis of procyanidin dimers: Regio- and stereocontrol of the interflavan bond
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A direct and general synthesis of procyanidin dimers B1, B2, B3 and B4 (10a-d) is presented. The approach is based on the stoichiometric coupling of two protected monomeric units (the nucleophilic 2a-b and electrophilic 4a-b partners) and deals with the regio- and stereocontrol of the C4-C8 interflavan bond as well as the control of the degree of oligomerization. The synthesis involves a five-step pathway starting from the native catechin (1a) or epicatechin (1b) to the fully deprotected dimers 10a-d. Furthermore, the process appears to be iterative as the coupling intermediates 9a-d themselves can be readily used in further selective syntheses of trimers or higher oligomers. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Tarascou, Isabelle,Barathieu, Karine,Andre, Yann,Pianet, Isabelle,Dufourc, Erick J.,Fouquet, Eric
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p. 5367 - 5377
(2007/10/03)
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- Synthetic studies of proanthocyanidins. Part 4. The synthesis of procyanidin B1 and B4: TMSOTf-catalyzed cyclization of catechin and epicatechin condensation
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Highly stereoselective synthesis of 3,4-trans series of (+)-catechin and (-)-epicatechin dimers under intramolecular condensation is described. Intramolecular condensation achieved an equimolar amount of coupling with 3,4-trans stereoselectivity and we succeeded in the synthesis of two 3,4-trans natural procyanidins, procyanidin-B1 and B4.
- Saito, Akiko,Nakajima, Noriyuki,Tanaka, Akira,Ubukata, Makoto
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p. 287 - 298
(2007/10/03)
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- Oligomeric flavanoids. Part 27. Interflavanyl bond formation in procyanidins under neutral conditions
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Dimethyl(methylthio)sulfonium tetrafluoroborate (DMTSF) and silver tetrafluoroborate (AgBF4) activate the C4-S bond in the 4-thioethers of flavan-3-ols toward carbon nucleophiles to permit formation of the interflavanyl bond in procyanidins under neutral conditions.
- Steynberg, Petrus J.,Nel, Reinier J.J.,Van Rensburg, Hendrik,Bezuidenhoudt, Barend C.B.,Ferreira, Daneel
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p. 8153 - 8158
(2007/10/03)
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- Proanthocyanidins from Lotus Corniculatus
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The chemical structure of the purified proanthocyanidin polymers of Lotus corniculatus was analysed by 13CNMR and by mild acid catalysed degradation in the presence of excess of phloroglucinol. The NMR data showed that the polymer was partially glycosidated with a number average Mr in the range 1800-2100 (six to seven flavanoid units). The products from phloroglucinol scission reaction indicated the extender flavan units to consist mostly of epicatechin (67%) and epigallocatechin (30%), with minor amounts of catechin and epiafzelechin units, which were linked together predominantly by C-4/C-8 interflavanoid bonds. The polymer chains were terminated mostly by catechin (83%) and, to a lesser extent, by epicatechin (16%). Copyright
- Foo,Newman,Waghorn,Mcnabb,Ulyatt
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p. 617 - 624
(2007/10/03)
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- Tannins from Betel Nuts
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From the acetone extract of fresh betel nuts, two procyanidin pentamers, two procyanidin tetramers and three procyanidin trimers, along with (+)-catechin, (-)-epicatechin, procyanidin A-1, procyanidin B-1, procyanidin B-2, and procyanidin B-7 were isolated. Based on 1H NMR and 13C NMR spectral data as well as the results of thiolysis degradation, the chemical structures of two series of oligomeric arecatannins A and B have been established. The arecatannins from betel nuts were found to be condensed-type tannins which possess (-)-epicatechin unit and (+)-catechin units. All arecatannins had C4-C8 linked (-)-epicatechin in the upper units whereas the (+)-catechin in the terminal unit had C4-C8 or C4-C6 linkage.
- Ma, Ying-Tsun,Hsu, Feng-Lin,Lan, Shu-Jan J.,Chen, Chieh-Fu
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- PROCYANIDIN DIMERS AND TRIMERS FROM DOUGLAS FIR INNER BARK
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The aqueous fraction of the inner bark extract of Douglas fir (Pseudotsuga menziesii) yielded two novel natural procyanidin trimers, epicatechin-(4β->8)-catechin-(4α->8)-catechin and epicatechin-(4β->6)-epicatechin-(4β->8)-epicatechin, and two known trimers, epicatechin-(4β->8)-epicatechin-(4β->8)-epicatechin and epicatechin-(4β->8)-epicatechin-(4β->8)-catechin.Catechin, epicatechin and procyanidin dimers B1, B2, B3 and B4 were also isolated.The structures of all of these procyanidins were elucinated from their 13C NMR data and by partial acid catalysed degradation with benzylthiol.Key Word Index - Pseudotsuga mentiesii; Pinaceae; flavon-3-ols; procyanidin; dimers; trimers; benzylthiol; degradation.
- Foo, Lai Yeap,Karchesy, Joseph J.
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p. 1743 - 1748
(2007/10/02)
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- PRENYLATED FLAVAN-3-OLS AND PROCYANIDINS FROM ILLICIUM ANISATUM
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Key Word Index-Illicium anisatum; Illiciaceae; prenylated flavan-3-ols; flavan-3-ols; procyanidins; tannins.Two prenylated flavan-3-ols were isolated from Illicium anisatum and their structures characterized by chemical and spectroscopic means as 8-(3,3-dimethylallyl)-(+)-catechin and 6-(3,3-dimethylallyl)-(+)-catechin.In addition, a new proanthocyanidin was isolated, together with several known compounds.The structure of the procyanidin was established as catechin-(4α8)-epicatechin-(4β8)-catechin.
- Morimoto, Satoshi,Tanabe, Hisako,Nonaka, Gen-Ichiro,Nishioka, Itsuo
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p. 907 - 910
(2007/10/02)
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- Tannins and Related Compounds. LX. Isolation and Characterization of Proanthocyanidins with a Doubly-Linked Unit from Vaccinium vitis-idaea L.
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New proanthocyanidin trimers (14 and 15) and tetramers (16 and 17) have been isolated from the whole body of Vaccinium vitis-idaea L. (Ericaceae).The structures of these proanthocyanidins were established by thiolytic degradation and by analyses of the proton and carbon-13 nuclear magnetic resonance spectra.In addition, the presence of (-)-epicatechin (1), (+)-catechin (2), (-)-epigallocatechin (3), (+)-gallocatechin (4), procyanidins B-1 (5), B-3 (6), A-1 (8) and A-2 (9), and cinnamtannins B1 (10), D1 (11), B2 (12) and D2 (13) in this plant was demonstrared.Keywords - Vaccinium vitis-idaea; Ericaceae; doubly-bonded proanthocyanidin; procyanidin; condensed tannin; flavan-3-ol; thiolytic degradation
- Morimoto, Satoshi,Nonaka, Gen-Ichiro,Nishioka, Itsuo
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- SYNTHESIS AND CHARACTERIZATION OF PROCYANIDIN DIMERS AS THEIR PERACETATES AND OCTAMETHYL ETHER DIACETATES
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Key Word Index - Biomimetic synthesis; procyanidins B1-B8; 3,4-cis-biflavanoid; all--bi--(+)-catechin; 1H NMR parameters. Condensation of (2R,3S,4R or S)-leucocyanidin or the 5,7,3',4'-tetramethyl ether of (2R,3R,4S)-leucocyanidin with flavan-3-ols yielded dimeric flavanoids which were converted to their octamethyl ether diacetates, or the deca-acetates for the 2,3-trans-procyanidin series.Comparison is made of the 1H NMR spectra of the deca-acetate and octamethyl ether diacetate derivatives which lead to useful diagnostic shift parameters characteristic of their structures.Condensation afforded a novel biflavanoid with a 3,4-cis-configuration and a triflavanoid of 'mixed' stereochemistry.
- Kolodziej, Herbert
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p. 1209 - 1216
(2007/10/02)
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- ACYLATED FLAVANOLS AND PROCYANIDINS FROM SALIX SIEBOLDIANA
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An homologous series of acylated flavan-3-ols and procyanidins have been isolated, together with the known procyanidins B-1, B-3 and trimer, from the bark of Salix sieboldiana.Chemical and spectroscopic evidence led to the assignments of their structures as the 3-O-(1,6-dihydroxy-2-cyclohexene-1-carboxylic acid ester) of (+)-catechin and the 1-hydroxy-6-oxo-2-cyclohexene carboxylic acid esters of (+)-catechin and procyanidins B-1, B-3 and trimer.Key Word Index - Salix sieboldiana; Salicaceae; bark; acylated flavan-3-ols; acylated procyanidins; 1-hydroxy-6-oxo-2-cyclohexene-1-carboxylic acid; 1,6-dihydroxy-2-cyclohexene-1-carboxylic acid .
- Hsu, Feng-Lin,Nonaka, Gen-Ichiro,Nishioka, Itsuo
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p. 2089 - 2092
(2007/10/02)
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- HETEROGENEITY OF INTERFLAVANOID BOND LOCATION IN LOBLOLLY PINE BARK PROCYANIDINS
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Procyanidins B-1 B-3 and B-7 were obtained from Pinus taeda phloem in yields of 0.076, 0.021 and 0.034percent of unextracted dry wt.Procyanidins B-1 and B-7 were produced in relative yields of 2.4:1 by biosynthetically patterned synthesis from catechin and loblolly pine tannins.Partial acid-catalysed thiolytic cleavage of loblolly pine phloem tannins produced (2R,3S,4S)-2,3-cis-3,4-trans-3,3',4',5,7-pentahydroxy-4-phenylthioflavan and both (2R,3R,4R)-2,3-cis-3,4-trans-3,3'4',5,7-pentahydroxy-4-flavan and (2R,3R,4R)-2,3-cis-3,4-trans-3,3',4',5,7-4-flavan in ratios of 3 : 1 demonstrating regio-isomerism of the interflavanoid linkage in the polymeric procyanidins of loblolly pine bark.Key Word Index - Pinus taeda; Pinaceae; loblolly pine; bark; phloem; procyanidins; condensed tannins; interflavanoid linkage; regio-isomerism.
- Hemingway, Richard W.,Karchesy, Joseph J.,McGraw, Gerald W.,Wielesek, Richard A.
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p. 275 - 282
(2007/10/02)
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- Condensed Tannins: Quinone Methide Intermediates in Procyanidin Synthesis
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Comparisons of acid- and base-catalysed reactions of epicatechin-(4β)-phenyl sulphide and leucocyanidin show that condensations proceed more rapidly at alkaline than at acidic pH so the biosynthesis of condensed tannins may occur through a quinone methide rather than a carbocation intermediate.
- Hemingway, Richard W.,Foo, L. Yeap
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p. 1035 - 1036
(2007/10/02)
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- Tannins and Related Compounds. I. Rhubarb (1)
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Three new tannin-related compounds (I, II and III), along with lindleyin (IV), (+)-catechin, 3-O-galloyl-(-)-epicatechin, gallic acid, 3,5,4'-trihydroxystilbene 4'-O-β-D-(6''-O-galloyl)-glucopyranoside, 3,5,4'-trihydroxystilbene 4'-O-β-D-glucopyranoside and 4-(4'-hydroxyphenyl)-2-butanone 4'-O-β-D-glucopyranoside, have been isolated from commercial rhubarb (Rhei Rhizoma).On the basis of spectral and chemical evidence, I, II and III were characterized as 3,3'-di-O-galloylprocyanidin B-2, 3-O-galloylprocyanidin B-1 and 1,2,6-tri-O-galloylglucose, respectively.The occurence of IV in rhubarb is of great significance, since IV has been reported to have analgesic and anti-inflammatory activities almost equal to those of aspirin and phenylbutanone.Tannins in rhubarb have been partially purified (designated as rhatannin (V)).Thiolysis degradation and enzymatic hydrolysis have shown that V is mainly composed of C4 to C8 linked 3-O-galloyl-(-)-epicatechin units in the extension part (upper part) with either 3-O-galloyl-(-)-epicatechin or (+)-catechin unit in the lower terminal part.Keywords. rhubarb; polygonaceae; 3,3'-di-O-galloylprocyanidin B-2; 3-O-galloylprocyanidin B-1; 1,2,6-tri-O-galloylglucose; lindleyin; rhatannin
- Nonaka, Gen-Ichiro,Nishioka, Itsuo,Nagasawa, Tetsuro,Oura, Hikokichi
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p. 2862 - 2870
(2007/10/02)
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