Two new gallotannins, pistafolins A (1) and B (2), were isolated from the leaf extract of Pistacia weinmannifolia. Their structures were determined by spectral methods.
High temperature liquid water(HTLW) has drawn increasing attention as an environmentally benign medium for organic chemical reactions,especially acid-/base-catalyzed reactions. Non-catalyzed hydrolyses of gallotannin ...High temperature liquid water(HTLW) has drawn increasing attention as an environmentally benign medium for organic chemical reactions,especially acid-/base-catalyzed reactions. Non-catalyzed hydrolyses of gallotannin and tara tannin in HTLW for the simultaneous preparation of gallic acid(GA) and pyrogallol(PY) are under investigation in our laboratory. In this study,the hydrolysis kinetics of gallotannin and tara tannin were determined. The reaction is indicated to be a typical consecutive first-order one in which GA has formed as a main intermediate and PY as the final product. Selective decomposition of tannin in HTLW was proved to be possible by adjusting reaction temperature and time. The present results provide an important basic data and reference for the green preparation of GA and PY.展开更多
A novel gallotannin, crenulatin (1), was isolated from the stem of Rhodiola crenulata, and its structure was determined by means of spectral analyses(including ~1H—~1H COSY, ~1H—^(13)C COSY and ~1H—^(13)C COLOC spe...A novel gallotannin, crenulatin (1), was isolated from the stem of Rhodiola crenulata, and its structure was determined by means of spectral analyses(including ~1H—~1H COSY, ~1H—^(13)C COSY and ~1H—^(13)C COLOC spectral measurements)and chemical evidence.展开更多
Three gallotannins,6-O-galloyl-D-glucose,3,6-di-O-galloyl-D-glucose and 3,4,6-tri-O-galloyl-D-glucose,were synthesized from gallic acid and D-glucose by a series of reactions which consisted of selective deprotecting,...Three gallotannins,6-O-galloyl-D-glucose,3,6-di-O-galloyl-D-glucose and 3,4,6-tri-O-galloyl-D-glucose,were synthesized from gallic acid and D-glucose by a series of reactions which consisted of selective deprotecting,esterifying partially protected glucose with tri-O-benzylgalloyl chlorides and acid hydrolysis.The intermediates were 6-O-galloyl-(1,2-O-isopropylidene)-α-D-glucofuranose,3,6-di-O-galloyl-(1,2-O-isopropylidene)-α-D-glucofuranose and 3,5,6-tri-O-galloyl-(1,2-O-isopropylidene)-α-D-glucofuranose.The data of thin-layer chromatography(TLC)and NMR assignments were presented for the gallotannins and intermediates.展开更多
文摘Two new gallotannins, pistafolins A (1) and B (2), were isolated from the leaf extract of Pistacia weinmannifolia. Their structures were determined by spectral methods.
基金Project supported by the National Natural Science Foundation ofChina (No. 20674068)the Natural Science Foundation of Zheji-ang Province, China (No. Y405157)
文摘High temperature liquid water(HTLW) has drawn increasing attention as an environmentally benign medium for organic chemical reactions,especially acid-/base-catalyzed reactions. Non-catalyzed hydrolyses of gallotannin and tara tannin in HTLW for the simultaneous preparation of gallic acid(GA) and pyrogallol(PY) are under investigation in our laboratory. In this study,the hydrolysis kinetics of gallotannin and tara tannin were determined. The reaction is indicated to be a typical consecutive first-order one in which GA has formed as a main intermediate and PY as the final product. Selective decomposition of tannin in HTLW was proved to be possible by adjusting reaction temperature and time. The present results provide an important basic data and reference for the green preparation of GA and PY.
文摘A novel gallotannin, crenulatin (1), was isolated from the stem of Rhodiola crenulata, and its structure was determined by means of spectral analyses(including ~1H—~1H COSY, ~1H—^(13)C COSY and ~1H—^(13)C COLOC spectral measurements)and chemical evidence.
文摘Three gallotannins,6-O-galloyl-D-glucose,3,6-di-O-galloyl-D-glucose and 3,4,6-tri-O-galloyl-D-glucose,were synthesized from gallic acid and D-glucose by a series of reactions which consisted of selective deprotecting,esterifying partially protected glucose with tri-O-benzylgalloyl chlorides and acid hydrolysis.The intermediates were 6-O-galloyl-(1,2-O-isopropylidene)-α-D-glucofuranose,3,6-di-O-galloyl-(1,2-O-isopropylidene)-α-D-glucofuranose and 3,5,6-tri-O-galloyl-(1,2-O-isopropylidene)-α-D-glucofuranose.The data of thin-layer chromatography(TLC)and NMR assignments were presented for the gallotannins and intermediates.
