As an exploration of synthesizing gallotannins,the natural products with versatile biological activities 3 o galloyl D glucose (7) was prepared from gallic acid (1) and D glucose (3).The phenol hydroxyl groups of gall...As an exploration of synthesizing gallotannins,the natural products with versatile biological activities 3 o galloyl D glucose (7) was prepared from gallic acid (1) and D glucose (3).The phenol hydroxyl groups of gallic acid were protected by benzylation which was cleaved subsequently by 10% palladised charcoal,and the four hydroxyl groups (1,2,4,6 ) of glucose shielded by isopropylation followed by acid hydrolysis.The structure was elucidated from the data of thin layer chromatography(TLC) and NMR spectrum.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As an exploration of synthesizing gallotannins,the natural products with versatile biological activities 3 o galloyl D glucose (7) was prepared from gallic acid (1) and D glucose (3).The phenol hydroxyl groups of gallic acid were protected by benzylation which was cleaved subsequently by 10% palladised charcoal,and the four hydroxyl groups (1,2,4,6 ) of glucose shielded by isopropylation followed by acid hydrolysis.The structure was elucidated from the data of thin layer chromatography(TLC) and NMR spectrum.
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.
