- The 2,2-Dimethyl-2-(ortho-nitrophenyl)acetyl (DMNPA) Group: A Novel Protecting Group in Carbohydrate Chemistry
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The 2,2-dimethyl-2-(ortho-nitrophenyl)acetyl (DMNPA) group was introduced to synthetic carbohydrate chemistry as a protecting group (PG) for the first time. Benefiting from a unique chemical structure and novel deprotection conditions, the DMNPA group can be cleaved rapidly and mutually orthogonal to other PGs. Orchestrated application of the DMNPA group with other PGs led to the highly efficient synthesis of the glycan of thornasterside A.
- Liu, Hui,Zhou, Si-Yu,Wen, Guo-En,Liu, Xu-Xue,Liu, De-Yong,Zhang, Qing-Ju,Schmidt, Richard R.,Sun, Jian-Song
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supporting information
p. 8049 - 8052
(2019/10/11)
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- 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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supporting information
p. 8240 - 8244
(2018/05/03)
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- Method for preparing and removing saccharide hydroxyl protecting group dimethyl phenylacetyl DMNA
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The invention relates to a method for preparing and removing saccharide hydroxyl protecting group dimethyl phenylacetyl DMNA. The method comprises the following steps: (1) efficiently introducing saccharide hydroxyl protecting group dimethyl phenylacetyl into saccharide hydroxyl; and (2) efficiently removing a hydroxyl protecting group shown in the description. The method is environmentally friendly and has the advantages that the advantages that the preparation is simple, the introduction is efficient, the operation is easy, the removal is efficient, and the application range is wide; and furthermore, a protecting group has very good stereoselectivity when being used for protecting 2-hydroxyl of a glycosyl donor, so that the development and application of the protecting group are promoted.
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Paragraph 0026; 0027; 0028; 0062; 0063; 0064
(2017/08/29)
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- HClO4-silica-catalysed regioselective opening of benzylidene acetals and its application towards regioselective HO-4 glycosylation of benzylidene acetals in one-pot
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Here we report a high-yielding method for the regioselective reductive ring opening of 4,6-O-benzylidene acetals of hexapyranosides using inexpensive and robust HClO4-SiO2 as the acidic catalyst and triethylsilane as the hydride dono
- Dara, Saidulu,Saikam, Varma,Yadav, Mahipal,Singh, Parvinder Pal,Vishwakarma, Ram A.
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supporting information
p. 93 - 96
(2014/05/20)
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- A practical approach to regioselective O-benzylation of primary positions of polyols
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Exposure of saccharide polyols to a moderate excess of benzyl bromide and DIPEA at 90 °C results in the regioselective O-benzylation of primary positions in moderate to good yields. The reactions can be performed without inert atmosphere and provide synth
- Giordano, Maddalena,Iadonisi, Alfonso
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p. 1550 - 1552
(2013/03/14)
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- TMDS as a dual-purpose reductant in the regioselective ring cleavage of hexopyranosyl acetals to ethers
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1,1,3,3-Tetramethyldisiloxane (TMDS) has been developed as an excellent dual-purpose reductant for the highly regioselective ring cleavage of various hexopyranosyl 4,6-O-acetals with Cu(OTf)2 or AlCl3 to afford the corresponding prim
- Zhang, Yin-Jie,Dayoub, Wissam,Chen, Guo-Rong,Lemaire, Marc
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experimental part
p. 1960 - 1966
(2012/05/20)
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- Some observations on the reductive ring opening of 4,6-O-benzylidene acetals of hexopyranosides with the borane trimethylamine-aluminium chloride reagent
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Reductive ring openings of 3-O-benzoyl-4,6-O-benzylidene-d-glucopyranosides with BH3·NMe3-AlCl3 are accompanied by side reactions, such as debenzoylation and reduction of the benzoate to benzyl ether. This phenomenon was r
- Daragics, Katalin,Szabó, Pál,Fügedi, Péter
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experimental part
p. 1633 - 1637
(2011/09/14)
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- Regioselective reductive ring opening of benzylidene acetals using triethylsilane and iodine
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Novel reaction conditions have been developed for the regioselective reductive ring opening of benzylidene acetals in carbohydrate derivatives using triethylsilane and molecular iodine. The reaction is fast, compatible with most of the functional groups e
- Panchadhayee, Rajib,Misra, Anup Kumar
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experimental part
p. 1193 - 1196
(2010/07/06)
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- Iodine-sodium cyanoborohydride-mediated reductive ring opening of 4,6-O-benzylidene acetals of hexopyranosides
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A quick, efficient and convenient method for the regiospecific reductive ring opening of 4,6-O-benzylidene acetals of O-/S-alkyl/aryl glycosides of mono- and disaccharides, leading to the exclusive formation of the corresponding 6-O-benzyl ethers, using s
- Rao, Kaki Venkata,Patil, Premanand R.,Atmakuri, Sridhar,Kartha, K.P. Ravindranathan
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experimental part
p. 2709 - 2713
(2011/02/21)
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- Metal trifluoromethanesulfonate-catalyzed regioselective reductive ring opening of benzylidene acetals
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A systematic study of various metal trifluoromethanesulfonates as efficient catalysts in the regioselective reductive ring opening of benzylidene acetals is described, including the effects of solvents, reducing agents, and temperature. These catalysts are found to be effective in cleaving the 4,6-O-acetal rings of hexopyranosides at either O4 or O6, respectively. When used in conjunction with a 1 M solution of BH3.THF in THF without extra addition of any solvent, it affects the ring fission at the O6 position to generate the corresponding primary alcohols, whereas O4-opening takes place in acetonitrile in the presence of dimethylethylsilane as the reductant leading to the secondary hydroxyl derivatives in high selectivity and yields. These methodologies can be applied to a wide range of substrates containing various functional groups.
- Shie, Chi-Rung,Tzeng, Zheng-Hao,Wang, Cheng-Chung,Hung, Shang-Cheng
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experimental part
p. 510 - 523
(2010/06/16)
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- Cu(OTf)2 as an efficient and dual-purpose catalyst in the regioselective reductive ring opening of benzylidene acetals
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(Chemical Equation Presented) Reducing the choices. Cu(OTf)2 is an efficient and dual-purpose catalyst for the highly regioselective reductive ring openings of benzylidene acetals with either BH3 or Me 2EtSiH to give the corresponding primary and secondary alcohols (see scheme). Isotope studies have confirmed that both modes of ring cleavage proceed by an SN1 reaction pathway when borane or silane attack the acetal carbon center.
- Shie, Chi-Rung,Tzeng, Zheng-Hao,Kulkarni, Suvarn S.,Uang, Biing-Jiun,Hsu, Ching-Yun,Hung, Shang-Cheng
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p. 1665 - 1668
(2007/10/03)
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- Oligosaccharide glycosides having mammalian immunosuppresive and tolerogenic properties
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Disclosed are novel oligosaccharide glycosides having mammalian immunosuppressive and tolerogenic properties, pharmaceutical compositions containing such oligosaccharide glycosides and to methods of using such oligosaccharide glycosides to modulate cell-m
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