- A selective ring opening reaction of 4,6-O-benzylidene acetals in carbohydrates using trialkylsilane derivatives
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Reductive ring opening reactions of 4,6-O-benzylidene-protected carbohydrates to the corresponding benzyl ethers using trialkylsilane derivatives were examined. When Et3SiH(or PS-DES(TM))-TfOH was used, 6-O- benzyl ethers with 4-hydroxy unsubst
- Sakagami, Masahiro,Hamana, Hiroshi
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- Phosphotungstic acid as a novel acidic catalyst for carbohydrate protection and glycosylation
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This work demonstrates the utilization of phosphotungstic acid (PTA) as a novel acidic catalyst for carbohydrate reactions, such as per-O-acetylation, regioselective O-4,6 benzylidene acetal formation, regioselective O-4 ring-opening, and glycosylation. These reactions are basic and salient during the synthesis of carbohydrate-based bioactive oligomers. Phosphotungstic acid's high acidity and eco-friendly character make it a tempting alternative to corrosive homogeneous acids. The various homogenous acid catalysts were replaced by the phosphotungstic acid solely for different carbohydrate reactions. It can be widely used as a catalyst for organic reactions as it is thermally stable and easy to handle. In our work, the reactions are operated smoothly under ambient conditions; the temperature varies from 0 °C to room temperature. Good to excellent yields were obtained in all four kinds of reactions.
- Chen, Jyun-Siao,Sankar, Arumugam,Lin, Yi-Jyun,Huang, Po-Hsun,Liao, Chih-Hsiang,Wu, Shen-Shen,Wu, Hsin-Ru,Luo, Shun-Yuan
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p. 33853 - 33862
(2019/11/11)
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- 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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- 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; 0053; 0054; 0055
(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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- Cyanuric chloride/sodium borohydride: A new reagent combination for reductive opening of 4,6-benzylidene acetals of carbohydrates to primary alcohols
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In the first such example, NaBH4 in combination with cyanuric chloride (TCT) has been used to obtain 6-hydroxy-4-benzyl ether derivatives from 4,6-benzylidene acetals of carbohydrates. The nature of hydride donor determines the regioselectivity
- Tatina, Madhubabu,Yousuf, Syed Khalid,Aravinda, Subrayashastry,Singh, Baldev,Mukherjee, Debaraj
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supporting information
p. 142 - 145
(2013/10/22)
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- 2,4,6-Trichloro-1,3,5-triazine (TCT) mediated one-pot sequential functionalisation of glycosides for the generation of orthogonally protected monosaccharide building blocks
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Orthogonally protected monosaccharide building blocks have been prepared using TCT in a one-pot multicomponent transformation. The process involves successive steps of arylidene acetalation, esterification and regioselective reductive acetal cleavage. High regioselectivity, scope for using a broad range of substrates, functional group tolerance, mild reaction conditions, easy handling process and wide application range are a few advantages of the current process.
- Tatina, Madhubabu,Yousuf, Syed Khalid,Mukherjee, Debaraj
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supporting information; experimental part
p. 5357 - 5360
(2012/07/30)
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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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- 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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- 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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- Synthesis of S-linked carbohydrate analogues via a Ferrier reaction
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In this work, the synthetic utility of the Ferrier reaction to access S-linked disaccharides and S-linked glycoamino acids has been probed. Significantly, entry to a range of 1,4- and 1,6-S-linked disaccharides has been achieved using glycals derived from glucose and galactose, and sulfur containing coupling partners derived from methyl α-d-glucopyranoside. Access to S-linked glycoamino acids and glycopeptides has also been achieved using protected cysteine and homocysteine coupling partners within the Ferrier reaction. Functionalisation of the Ferrier products, for example, via dihydroxylation using OsO4 or amino acid coupling, and deprotection of the targets have also been achieved. In this way, entry to materials of interest as mimics of biologically interesting disaccharides and glycopeptides has been realised, including targets derived from rare sugars such as talopyranose and gulopyranose.
- Ellis, David,Norman, Sarah E.,Osborn, Helen M.I.
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p. 2832 - 2854
(2008/09/19)
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- A simple procedure for connecting two carbohydrate moieties by click chemistry techniques
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We describe a procedure to link two saccharides by click chemistry techniques. This methodology allows the generation of new molecules in which two carbohydrates are connected through a triazole ring. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Gouin, Sebastien G.,Bultel, Laurent,Falentin, Celine,Kovensky, Jose
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p. 1160 - 1167
(2008/02/08)
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- Facile chelation-controlled reductive opening of methoxybenzylidene acetals with Bu3SnH and MgBr2. Regioselective protection strategy as MPM ethers
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A mild and efficient regioselective reductive opening of methoxybenzylidene acetals using a combination of Bu3SnH and MgBr2·OEt2, mainly via five-membered chelation intermediates is described. This reaction was applied to synthetic intermediates of myriaporon and tedanolide. (C) 2000 Elsevier Science Ltd.
- Zheng,Yamauchi,Dei,Kusaka,Matsui,Yonemitsu
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p. 6441 - 6445
(2007/10/03)
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- Preparation of cyclic peptide antifungal agents
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The present invention provides phosphonylating agents and phosphonylation conditions that are compatible with the acid- and base-sensitive compounds and which promote a regioselective and reproducible conversion to a phosphonate compound. Also provided are intermediates that may be used to prepare phosphonate derivatives of cyclic peptides antifungal agent and a process for converting the phosphonates to the desired phosphonic acid prodrugs.
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- Structure and reactions of glycopyranoside derived dialdehydes
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Several 4- protected D-glucopyranosides were synthesized and cleaved by sodium metaperiodate. Depending on the protection pattern the resulting dialdehydes showed different types of structures. Predominantly dioxane structures of the hemiacetal or hemiald
- Heidelberg, Thorsten,Thiem, Joachim
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p. 223 - 232
(2007/10/03)
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- A method for the selective reduction of carbohydrate 4,6-O-benzylidene acetals
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Glucose-derived 4,6-O-benzylidene acetals can be selectively reduced to the corresponding 6-O-benzyl derivatives by the treatment with trifluoroacetic acid and triethylsilane.
- DeNinno, Michael P.,Etienne, John B.,Duplantier, Kimberly C.
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p. 669 - 672
(2007/10/02)
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