The first construction of a 3,6-bridged ellagitannin skeleton with 1C4/B glucose core; synthesis of nonamethylcorilagin

Ikeda, Yasunori; Nagao, Kohei; Tanigakiuchi, Koki; Tokumaru, Go; Tsuchiya, Hitoshi; Yamada, Hidetoshi

doi:10.1016/j.tetlet.2003.11.006

Cited by 36 publications

(32 citation statements)

References 25 publications

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“…(1)], that is, the desired product 3 was not produced by treatment of 2 with CuCl 2 / n BuNH 2 , a reagent combination that effectively coupled 4‐O‐benzylated gallates intramolecularly 7. 11 We encountered a similar problem in the synthesis of 5 ,12 and overcame it by using a temporary‐ring‐opening strategy (Scheme ),7 in which the flexible conformation of digallate 4 allowed the two galloyl groups to get in close proximity to each other, and thus their intramolecular coupling. After the formation of the 3,6‐HHDP bridge, reconstruction of the pyranose ring furnished the HHDP‐bridged glucopyranose moiety of 5 .…”

Section: Methodsmentioning

confidence: 99%

Determination of the Catalytic Pathway of a Manganese Arginase Enzyme Through Density Functional Investigation

Leopoldini

Russo

Toscano

2009

Chemistry A European J

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The catalytic mechanism of dimanganese-containing arginase enzyme has been investigated by DFT calculations. Two exchange-correlation functionals, B3 LYP and MPWB1 K, have been used to construct the potential energy profiles for the hydrolysis of an arginine substrate performed by an arginase active site model system. Two reaction mechanisms have been investigated, one involving a water molecule (mechanism 1) and the other involving a hydroxide ion (mechanism 2) as nucleophilic agent. Results obtained in the gas phase and in the protein environment have indicated that mechanism 1 involving a water molecule entails structural features as well as an activation energy for the rate-determining step that are inconsistent with experimental data available for the arginase enzyme. On the other hand, when a hydroxide ion is present at the Mn2 site, a lower activation energy and a structural arrangement closer to the experimental indication are obtained.

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Section: Methodsmentioning

confidence: 99%

Determination of the Catalytic Pathway of a Manganese Arginase Enzyme Through Density Functional Investigation

Leopoldini

Russo

Toscano

2009

Chemistry A European J

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“…In particular,production of the axial-rich ellagitannins from 1 is still at the suppositional level. Fora xial chirality of the HHDP group,i ts eems that synthetic work has verified the hypothesis by showing that the couplings at the 1,6-, [15] 2,3-, [16,17] 3,4-, [18] 3,6-, [19,20] and 4,6-positions [21][22][23][24] almost reflect the axial chirality in natural products.H owever,t he verification is deficient because all reactants used in the reported work are partly galloylated glucose,w hich cannot mimic the reaction of the fully galloylated 1.A lthough as imple chemical reaction cannot reflect the biosynthesis where enzymes may take charge of the transformations,i ti si mportant to understand behaviors in non-enzymatic oxidation of 1 in the process of clarifying the biosyntheses of ellagitannins because the galloyl group can also couple non-enzymatically.However,simple oxidation of unprotected galloyl groups produces various types of reaction products,t hus making an analysis focused on the oxidation products difficult. In this study,w ei nvestigated non-enzymatic oxidation of 5 (Figure 1), an analogue of 1,and thereby reveal which 4-O-benzylated galloyl groups tended to couple…”

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confidence: 71%

Non‐Enzymatic Oxidation of a Pentagalloylglucose Analogue into Members of the Ellagitannin Family

et al. 2017

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The occurrence of more than 1000 structurally diverse ellagitannins has been hypothesized to begin with the oxidation of penta-O-galloyl-β-d-glucose (β-PGG) for the coupling of the galloyl groups. However, the non-enzymatic behavior of β-PGG in the oxidation is unknown. Disclosed herein is which galloyl groups tended to couple and which axial chirality was predominant in the derived hexahydroxydiphenoyl groups when an analogue of β-PGG was subjected to oxidation. The galloyl groups coupled in the following order: at the 4,6-, 1,6-, 1,2-, 2,3-, and 3,6-positions with respective S-, S-, R-, S-, and R-axial chirality. Among them, the most preferred 4,6-coupling reflected the what was observed for natural ellagitannins. A new finding was that the second best coupling occured at the 1,6-positions. With the detection of a 3,6-coupled product, this work demonstrated that even ellagitannin skeletons with an axial-rich glucose core may be generated non-enzymatically.

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“…In particular, production of the axial‐rich ellagitannins from 1 is still at the suppositional level. For axial chirality of the HHDP group, it seems that synthetic work has verified the hypothesis by showing that the couplings at the 1,6‐, 2,3‐, 3,4‐, 3,6‐, and 4,6‐positions almost reflect the axial chirality in natural products. However, the verification is deficient because all reactants used in the reported work are partly galloylated glucose, which cannot mimic the reaction of the fully galloylated 1 .…”

Section: Figurementioning

confidence: 84%

Non‐Enzymatic Oxidation of a Pentagalloylglucose Analogue into Members of the Ellagitannin Family

et al. 2017

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The occurrence of more than 1000 structurally diverse ellagitannins has been hypothesized to begin with the oxidation of penta-O-galloyl-b-d-glucose (b-PGG) for the coupling of the galloylg roups.H owever,t he non-enzymatic behavior of b-PGG in the oxidation is unknown. Disclosed herein is whichgalloylgroups tended to couple and whichaxial chirality was predominant in the derived hexahydroxydiphenoyl groups when an analogue of b-PGG was subjected to oxidation. The galloylg roups coupled in the following order: at the 4,6-, 1,6-, 1,2-, 2,3-, and 3,6-positions with respective S-, S-, R-, S-, and R-axial chirality.A mong them, the most preferred 4,6-coupling reflected the what was observed for natural ellagitannins.Anew finding was that the second best coupling occured at the 1,6-positions.W ith the detection of a3 ,6-coupled product, this work demonstrated that even ellagitannin skeletons with an axial-richg lucose core may be generated non-enzymatically.

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The first construction of a 3,6-bridged ellagitannin skeleton with 1C4/B glucose core; synthesis of nonamethylcorilagin

Cited by 36 publications

References 25 publications

Determination of the Catalytic Pathway of a Manganese Arginase Enzyme Through Density Functional Investigation

Determination of the Catalytic Pathway of a Manganese Arginase Enzyme Through Density Functional Investigation

Non‐Enzymatic Oxidation of a Pentagalloylglucose Analogue into Members of the Ellagitannin Family

Non‐Enzymatic Oxidation of a Pentagalloylglucose Analogue into Members of the Ellagitannin Family

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