- Mapping the Relationship between Glycosyl Acceptor Reactivity and Glycosylation Stereoselectivity
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The reactivity of both coupling partners—the glycosyl donor and acceptor—is decisive for the outcome of a glycosylation reaction, in terms of both yield and stereoselectivity. Where the reactivity of glycosyl donors is well understood and can be controlled through manipulation of the functional/protecting-group pattern, the reactivity of glycosyl acceptor alcohols is poorly understood. We here present an operationally simple system to gauge glycosyl acceptor reactivity, which employs two conformationally locked donors with stereoselectivity that critically depends on the reactivity of the nucleophile. A wide array of acceptors was screened and their structure–reactivity/stereoselectivity relationships established. By systematically varying the protecting groups, the reactivity of glycosyl acceptors can be adjusted to attain stereoselective cis-glucosylations.
- van der Vorm, Stefan,van Hengst, Jacob M. A.,Bakker, Marloes,Overkleeft, Herman S.,van der Marel, Gijsbert A.,Codée, Jeroen D. C.
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p. 8240 - 8244
(2018/05/03)
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- Synthesis of MeON-neoglycosides of digoxigenin with 6-deoxy- and 2,6-dideoxy-D-glucose derivatives and their anticancer activity
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Cardiac glycosides show anticancer activities and their deoxy-sugar chains are vital for their anticancer effects. In order to study the structure-activity relationship (SAR) of cardiac glycosides toward cancers and get more potent anticancer agents, a series of MeON-neoglycosides of digoxigenin was synthesized and evaluated. First, ten 6-deoxy- and 2,6-dideoxy-D-glucopyranosyl donors were synthesized starting from methyl α-D-glucopyranoside and 2-deoxy-D-glucose. Meanwhile, the digoxigenin was obtained by acidic hydrolysis of commercially available digoxin as glycosyl acceptor. Then, a 22-member MeON-neoglycoside library of digoxigenin was successfully synthesized by neoglycosylation method. Finally, the induction of Nur77 expression and its translocation from the nucleus to cytoplasm together with cytotoxicity of these MeON-neoglycosides were evaluated. The SAR analysis revealed that C3 glycosylation is required for their induction of Nur77 expression. Moreover, some MeON-neoglycosides (2b and 8b) could significant induce the expression of Nur77 and its translocation from the nucleus to cytoplasm. However, these compounds showed no inhibitory effects on the proliferation of cancer cells, suggesting that they may not induce apoptosis of NIH-H460 cancer cells and their underlying potential and application toward cancer cells deserves future study.
- Wang, Dong-dong,Li, Xiao-san,Bao, Yu-zhou,Liu, Jie,Zhang, Xiao-kun,Yao, Xin-sheng,Sun, Xue-Long,Tang, Jin-Shan
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p. 3359 - 3364
(2017/07/07)
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- Stereoselective synthesis of α-linked 2-deoxy glycosides enabled by visible-light-mediated reductive deiodination
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2-Deoxy sugars and their derivatives occur abundantly in many pharmaceutically important natural products. However, the construction of specific 2-deoxy-glycosidic bonds remains as a challenge. Herein, we report an efficient way to prepare 2-deoxy-a-glycosides by glycosylation of 2-iodo-glycosyl acetate and subsequent visible-light-mediated tin-free reductive deiodination. We have successfully applied the postglycosylational-deiodination strategy in the synthesis of more than 30 mono-, di-, tri-, tetra- and pentadeoxysaccharides with excellent stereoselectivity and efficiency. This method has also been applied to the synthesis of a 2-deoxy-tetrasac-charide containing four a-linkages.
- Wang, Hao,Tao, Jinyi,Cai, Xinpei,Chen, Wei,Zhao, Yueqi,Xu, Yang,Yao, Wang,Zeng, Jing,Wan, Qian
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p. 17319 - 17323
(2015/02/19)
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- Stereoselective mannich-like reactions of ester enolates generated on sugar templates: A novel access to a key intermediate for 1β-methylcarbapenem synthesis
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The Mannich-like reactions of the enolates generated from 2,3-di-O-protected 6-deoxy-4-O-propionyl-α-D-glucopyranosides with (3R,4R)-4-acetoxy-3-((R)-1-(t-butyldimethylsilyloxy)ethyl ]azetidin-2-one were investigated. The corresponding 2,3-di-O-methyl derivative provided the Mannich adduct in good to excellent stereoselectivity. From the major adduct, the azetidin-2-one incorporating an α-methyl acetic acid side chain at the C-4 position with ?-configuration was obtained by alkaline hydrolysis. This product, (3S,4S)-3-[(R)-1-(t-butyldimethylsilyloxy)ethyl 1-4-1(R)-1-carboxyethylJazetidin-2-one, is a useful intermediate for the 1 ?-methylcarbapenem synthesis.
- Sasaki, Daisuke,Sawamoto, Daisuke,Takao, Ken-ichi,Tadano, Kin-ichi,Okue, Masayuki,Ajito, Keiichi
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p. 103 - 110
(2008/02/13)
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- Application of the Synthetic Aminosugars for Glycodiversification: Synthesis and Antimicrobial Studies of Pyranmycin
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A divergent approach was employed for the synthesis of aminosugars, from which a novel library of aminoglycoside antibiotics (pyranmycins) was synthesized. Pyranmycins have comparable antibacterial activity as neomycin, a clinically used aminoglycoside antibiotic, against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, and Mycobacterium smegmatis. In addition, pyranmycins, like streptomycin, are bacteriocidal while isoniazid (INH) is bacteriostatic. Therefore, pyranmycins may provide new therapeutic options in the treatment against tuberculosis. Several members of pyranmycins also manifest modest anti-Tat and anti-Rev activities, which may aid in the development of new anti-HIV agents. Although the antibacterial activity of pyranmycins against aminoglycoside resistant bacteria is less than expected, the synthetic methodologies of utilizing a library of aminosugars can be a model for future studies of glycodiversification or glycorandomization.
- Elchert, Bryan,Li, Jie,Wang, Jinhua,Hui, Yu,Rai, Ravi,Ptak, Roger,Ward, Priscilla,Takemoto, Jon Y.,Bensaci, Mekki,Chang, Cheng-Wei Tom
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p. 1513 - 1523
(2007/10/03)
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- Highly diastereoselective 1,4-addition of an organocuprate to methyl α-D-gluco-, α-D-manno-, or α-D-galactopyranosides tethering an α,β-unsaturated ester. Novel asymmetric access to β-C-substituted butanoic acids
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The 1,4-addition of magnesium divinylcuprate prepared from vinylmagnesium bromide and cuprous bromide to some 4-O-crotonyl derivatives of methyl α-D-glucopyranoside proceeds with a high level of diastereochemical induction, providing the adduct in good-to
- Totani,Nagatsuka,Yamaguchi,Takao,Ohba,Tadano
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p. 5965 - 5975
(2007/10/03)
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- Highly stereoselective 1,4-conjugate addition of organocopper reagents to methyl α-D-glucopyranoside derivatives tethering an unsaturated ester moiety at C-4 or C-6
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(formula presented) The 1,4-conjugate additions of a variety of organocopper reagents to some 4-O-crotonyl derivatives of methyl α-D-glucopyranoside proceeded with a high level of diastereochemical induction to provide the adducts carrying a β-substituted
- Totani, Kiichiro,Nagatsuka, Takayuki,Takao, Ken-Ichi,Ohba, Shigeru,Tadano, Kin-Ichi
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p. 1447 - 1450
(2008/02/09)
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- SYNTHESIS OF STEREOSPECIFICALLY LABELED CARBOHYDRATES II: PREPARATION OF (3S)- AND (3R)-ABEQUOSE
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Preparation of methyl 3,6-dideoxy-D-xylo-hexapyranoside (methyl abequoside) having deuterium stereospecifically labeled at the 3S (1) and 3R (2) position, respectively, via three different routes is described.
- Weigel, Theresa M.,Liu, Hung-wen
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p. 4221 - 4224
(2007/10/02)
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- Partially Benzylated Derivatives of 6-Deoxy-D-glucose
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Several partially benzylated derivatives of 6-deoxy-D-glucose (D-quinovose) were synthesized from appropriate di-O-benzyl-D-glucosides whose primary hydroxyl group is unprotected, via unimolar tosylation and subsequent reduction with LiAlH4.
- Koto, Shinkiti,Morishima, Naohiko,Mori, Yoko,Tanaka, Hitoshi,Hayashi, Seiichi,et al.
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p. 2301 - 2303
(2007/10/02)
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