- Comparison of Several Glucuronate Glycosyl Donors
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Methyl 3,4-di-O-benzyl-[(S)-1,2-O-(1-cyanoethylidene)]-α-D- glucopyranuronate (12), methyl 3,4-di-O-benzyl-[(S)-1,2-O-(1-ethoxyethylidene)]- α-D-glucopyranuronate (14), methyl 2-O-acetyl-3,4-di-O-benzyl-α-D- glucopyranuronate bromide (15), methyl (2-O-acetyl-3,4-di-O-benzyl-α-D- glucopyranosyl)uronate trichloroacetimidate (17), and methyl (2,3,4-tri-O-benzyl-α/β-D-glucopyranosyl)uronate trichloroacetimidate (30) were synthesized and used as glycosyl donors. Glycosylation reactions of 12 with (5-R)-2,3,4,5-tetrahydro-5-trityloxymethyl-2- furanone (32) and 14,15,17 with the corresponding (5-R)-2,3,4,5-tetrahydro-5- hydroxymethyl-2-furanone (31) provided the exclusively β-linked glucuronide 33 in 69%, 28%, 45%, and 71% yield, respectively. The coupling of donor 30 with acceptor 31 furnished the glucuronated lactone 35 in 70% yield with a surprisingly high content (20%) of the undesired α-linked sugar residue. The structure of 33 was proved by NMR and X-ray diffraction studies. In a model reaction a complete deprotection procedure of the glucuronic acid lactone conjugation was demonstrated.
- Pews-Davtyan, Anahit,Pirojan, Alexander,Shaljyan, Izabella,Awetissjan, Aida A.,Reinke, Helmut,Vogel, Christian
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p. 939 - 962
(2007/10/03)
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- Stereoselective Syntheses of α-Glucuronides Using Dehydrative Glycosylation
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Methyl and benzyl 2,3,4-tri-O-benzyl-D-glucopyranuronates, prepared from D-glucurono-6,3-lactone, afforded selectively the corresponding α-glucopyranosiduronates by the aid of the condensing reagent system composed of p-nitrobenzenesulfonyl chloride, silver trifluoromethanesulfonate, and triethylamine. Using this method, O-α-D-glucopyranuronosyl-(1→3)-O-α-L-arabinofuranosyl- (1→3)-D-xylopyranose, one of the minimal component units in the structure of plantago-mucilage A from the seeds of Plantago asiatica Linne constituting a Chinese medicine : chegianzi [HU~P].
- Koto, Shinkiti,Miura, Teruhisa,Hirooka, Motoko,Tomaru, Aya,Iida, Mika,Kanemitsu, Masanori,Takenaka, Kazuhiro,Masuzawa, Shinichi,Miyaji, Saeko,Kuroyanagi, Naoko,Yagishita, Miki,Zen, Shonosuke,Yago, Kazuo,Tomonaga, Fumiya
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p. 3247 - 3259
(2007/10/03)
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