84316-82-5Relevant academic research and scientific papers
Non-Enzymatic Oxidation of a Pentagalloylglucose Analogue into Members of the Ellagitannin Family
Ashibe, Seiya,Ikeuchi, Kazutada,Kume, Yuji,Wakamori, Shinnosuke,Ueno, Yuri,Iwashita, Takashi,Yamada, Hidetoshi
supporting information, p. 15402 - 15406 (2017/11/10)
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.
Total synthesis of (+)-davidiin
Kasai, Yusuke,Michihata, Naoki,Nishimura, Hidehisa,Hirokane, Tsukasa,Yamada, Hidetoshi
supporting information; experimental part, p. 8026 - 8029 (2012/08/29)
Quite strained: The total synthesis of (+)-davidiin, an ellagitannin with more substituents in axial than in equatorial positions, requires a conformational lock of the glucose, induced by steric repulsion between adjacent bulky silyloxy groups. This conformational lock played a pivotal role in 1) the β-selective formation of the glycosyl ester at the anomeric position, 2) the formation of the 1,6-HHDP bridge, and 3) the complete control of axial chirality in the aryl-aryl coupling. Copyright
