- Activation of glycosyl phosphites under neutral conditions in solutions of metal perchlorates in organic solvents
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Glycosyl phosphites 1-3 derived from glucose are activated under neutral conditions and without the addition of any further promoter in 1 M solutions of LiClO4, Mg(ClO4)2 or Ba(ClO4)2 in ether, CHsub
- Schene, Heidrun,Waldmann, Herbert
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- Effect of dimethoxyethane in Yb(OTf)3-promoted glycosidations
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1,2-Dimethoxyethane (DME) is shown to be a suitable co-solvent for sensibly improving the α-selectivity of glycosidations performed with trihaloacetimidate donors. This solvent works equally well by using either moisture stable Yb(OTf)3 or standard TMSOTf as the promoters.
- Adinolfi, Matteo,Iadonisi, Alfonso,Ravidà, Alessandra,Schiattarella, Marialuisa
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Read Online
- A Streamlined Regenerative Glycosylation Reaction: Direct, Acid-Free Activation of Thioglycosides
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Our group has previously reported that 3,3-difluoroxindole (HOFox) is able to mediate glycosylations via intermediacy of OFox imidates. Thioglycoside precursors were first converted into the corresponding glycosyl bromides that were then converted into the OFox imidates in the presence of Ag2O followed by the activation with catalytic Lewis acid in a regenerative fashion. Reported herein is a direct conversion of thioglycosides via the regenerative approach that bypasses the intermediacy of bromides and eliminates the need for heavy-metal-based promoters. The direct regenerative activation of thioglycosides is achieved under neutral reaction conditions using only 1 equiv. NIS and catalytic HOFox without the acidic additives.
- Escopy, Samira,Singh, Yashapal,Stine, Keith J.,Demchenko, Alexei V.
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p. 354 - 361
(2020/12/02)
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- Synthesis of photolabile group protected anomeric acetals and its application in carbohydrate synthesis with the assistance of continuous flow photo-reactor
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Selective deprotection of photolabile anomeric 2-nitrobenzyl acetals was achieved using continuous flow photo-reactor (UV radiation at 355 nm) in methanol-water. Various protecting groups such as acetyl, benzyl, benzoyl, benzylidine, TBS, etc. were found to be highly stable during the photolysis.
- Tiwari, Varsha,Badavath, Vishnu Nayak,Singh, Adesh Kumar,Kandasamy, Jeyakumar
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p. 227 - 236
(2020/03/18)
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- AuCl3-AgOTf promoted O-glycosylation using anomeric sulfoxides as glycosyl donors at room temperature
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Activation of sulfoxide as glycosyl donors using AuCl3/AgOTf reagent system has been described. Under optimal reaction conditions, both armed and disarmed glycosyl sulfoxide donors were found to react with a range of primary, secondary, and tertiary alcohol acceptors, and sugar derived glycosyl acceptors to afford the corresponding glycosides in moderate to good yields with predictable selectivity. The reactions are quick (20–60 min), facile at room temperature and the reactions conditions tolerate acid sensitive groups.
- Palanivel, Ashokkumar,Chennaiah, Ande,Dubbu, Sateesh,Mallick, Asadulla,Vankar, Yashwant D.
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- Glycosyl ortho-Methoxybenzoates: Catalytically Activated Glycosyl Donors with an Easily Removable and Recyclable Leaving Group
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We describe the β-ortho-methoxybenzoate as a shelf stable and practical C-1 nucleofuge for catalytic chemical glycosylation in which the benzoic acid by-product can be easily removed, reisolated, and potentially recycled after the glycosylation reaction. This new type of glycosyl donor can be efficiently activated by a range of promoters, including Bi(OTf)3, Fe(OTf)3, TMSOTf (TMS = trimethylsilyl), and triflic acid, with low (10 mol-%) catalyst loadings. The donor shows higher reactivity than analogous benzoate, p-methoxybenzoate and p-cyano-o-methoxybenzoate donors. In glycosylation reactions with o-methoxybenzoate donors, the yields of disaccharide products were good to excellent for various glycosyl acceptors, including a carbohydrate-based secondary alcohol. Furthermore, β-selective mannosylation was achieved with a Crich-type donor at 0 °C to ambient temperature, without donor preactivation. The donor was also used for the first step of a one-pot two-step glycosylation to obtain a trisaccharide; the second coupling involved activation of a thioglycoside with NIS/TMSOTf (NIS = N-iodosuccinimide). We believe that this offers a good alternative to current protocols.
- Kristensen, Steffan K.,Salamone, Stéphane,Rasmussen, Michelle R.,Marqvorsen, Mikkel H. S.,Jensen, Henrik H.
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p. 5365 - 5376
(2016/11/22)
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- Palladium-controlled β-selective glycosylation in the absence of the C(2)-ester participatory group
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The development of a new glycosylation method for the stereoselective synthesis of β-glycosides in the absence of the traditional C(2)-ester neighboring group effect is described. This process relies on the ability of the cationic palladium catalyst, Pd(P
- Mensah, Enoch A.,Azzarelli, Joseph M.,Nguyen, Hien M.
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supporting information; experimental part
p. 1650 - 1657
(2009/07/10)
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- An efficient glycosylation protocol with glycosyl ortho-alkynylbenzoates as donors under the catalysis of Ph3PAuOTf
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A new and powerful glycosylation protocol with glycosyl ortho-alkynylbenzoates as donors and Ph3PAuOTf as a promoter is disclosed. The donors are readily available and stable; the glycosidic coupling yields are generally excellent; the promotion system is catalytic, neutral, and orthogonal to the known glycosylation conditions.
- Li, Yao,Yang, You,Yu, Biao
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p. 3604 - 3608
(2008/09/21)
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- The synthesis of 2-, 3-, 4- and 6-O-α-d-glucopyranosyl-d-galactopyranose, and their evaluation as nutritional supplements for pre-term infants
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Four methods have been screened for the synthesis of some α-d-glucopyranosides, with the recently reported (Mukaiyama) combination of 2,3,4,6-tetra-O-benzyl-α-d-glucopyranosyl iodide and triphenylphosphine oxide being the most successful, especially in th
- Meloncelli, Peter J.,Williams, Tracey M.,Hartmann, Peter E.,Stick, Robert V.
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p. 1793 - 1804
(2008/02/10)
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- Versatile synthesis and mechanism of activation of S-benzoxazolyl glycosides
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(Chemical Equation Presented) As a part of a program for developing new efficient procedures for stereoselective glycosylation, a range of S-benzoxazolyl (SBox) glycosides have been synthesized. The mechanistic aspects of the SBox moiety activation for gl
- Kamat, Medha N.,Rath, Nigam P.,Demchenko, Alexei V.
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p. 6938 - 6946
(2008/02/11)
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- Revisiting the armed-disarmed concept: The importance of anomeric configuration in the activation of S-benzoxazolyl glycosides
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The unexpectedly high reactivity of a (2-benzoxazolyl) per-O-benzoyl- β-D-thioglucoside and related donors in reactions promoted by copper(II) trifluoromethanesulfonate is revealed, by comparison with the unreactive α-anomer, to be the result of neighbori
- Crich, David,Li, Ming
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p. 4115 - 4118
(2008/02/12)
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- Remarkably efficient activation of glycosyl trichloro- and (N-phenyl)trifluoroacetimidates with bismuth(III) triflate
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Easily handled and nontoxic Bi(OTf)3 is a powerful activator for trichloro- and (N-phenyl)trifluoroacetimidate glycosyl donors. This catalyst allows glycosidations to be performed at low temperatures in very short times. Rewarding yields were o
- Adinolfi, Matteo,Iadonisi, Alfonso,Ravidà, Alessandra,Valerio, Silvia
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p. 2595 - 2599
(2007/10/03)
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- Reconsidering glycosylations at high temperature: Precise microwave heating
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Current methods for glycosylation of complex alcohols, e.g. with glycosyl trichloroacetimidates, generally occur in the presence of a strong Lewis acid 'promoter', and at sub-ambient temperatures. However, the older literature reports high-temperature gly
- Larsen, Kim,Worm-Leonhard, Kasper,Olsen, Peter,Hoel, Andreas,Jensen, Knud J.
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p. 3966 - 3970
(2007/10/03)
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- Revisiting the armed-disarmed concept rationale: S-benzoxazolyl glycosides in chemoselective oligosaccharide synthesis
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(Chemical Equation Presented) It has been discovered that 2-O-benzyl-3,4,6-tri-O-acyl SBox glycosides are significantly less reactive than even "disarmed" peracylated derivatives. This finding has been applied to the synthesis of various oligosaccharides,
- Kamat, Medha N.,Demchenko, Alexei V.
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p. 3215 - 3218
(2007/10/03)
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- Glycosylation with 2′-carboxybenzyl glycosides as glycosyl donors: Scope and application to the synthesis of a tetrasaccharide
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Glycosylation of 2′-carboxybenzyl (CB) 2,3,4,6-tetra-O-benzyl-α-D-mannopyranoside (3), CB 2,3,4,6-tetra-O-benzyl-β-D-glucopyranoside (4), and CB 2,3-di-O-benzyl-4,6-O-benzylidene-β-D-glucopyranoside (5) as glycosyl donors with various glycosyl acceptors p
- Kim, Kwan Soo,Kang, Sung Soo,Seo, Yong Sung,Kim, Hyo Jin,Lee, Yong Joo,Jeong, Kyu-Sung
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p. 1311 - 1314
(2007/10/03)
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- Synthesis of anomeric sulfimides and their use as a new family of glycosyl donors
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We introduce a convenient synthesis of anomeric sulfimides, the ability of which to act as glycosyl donors has been tested with various thiophilic reagents and acceptors.
- Chery, Florence,Cassel, Stephanie,Wessel, Hans Peter,Rollin, Patrick
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p. 171 - 180
(2007/10/03)
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- Glycosyl trifluoroacetimidates. Part 1: Preparation and application as new glycosyl donors
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Glycosyl (N-phenyl)trifluoroacetimidates, readily prepared from 1-hydroxyl sugars by treatment with (N-phenyl)trifluoroacetimidoyl chloride in the presence of K2CO3, were demonstrated to be effective glycosyl donors.
- Yu, Biao,Tao, Houchao
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p. 2405 - 2407
(2007/10/03)
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- Activation of glycosyl phosphates by in situ conversion to glycosyl iodides under neutral conditions in concentrated solutions of lithium perchlorate in organic solvents
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Glycosyl phosphates are converted in situ into glycosyl iodides and thereby advantageously employed as glycosyl donors under mild neutral conditions by treatment with LiI in IM solutions of LiClO4 in organic solvents.
- Schmid, Uschi,Waldmann, Herbert
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p. 3837 - 3840
(2007/10/03)
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- Glycosyl sulfates as glycosyl donors
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Glycosyl sulfates are easily synthesised from tetrabenzyl pyranoses; their reaction with various acceptors promoted by Lewis acids affords glycosides and disaccharides as α,β mixtures.
- Cipolla, Laura,Lay, Luigi,Nicotra, Francesco,Panza, Luigi,Russo, Giovanni
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p. 8669 - 8670
(2007/10/02)
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- Catalytic O- and S-Glycosylation of 1-Hydroxy Sugars
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O-Protected 1-hydroxy sugars are effectively cross-coupled with a variety of alcohols and thiols to give the corresponding glycosides by using methoxyacetic acid and ytterbium(III) trifluoromethanesulfonate as catalytic promoters.
- Inanaga, Junji,Yokoyama, Yasuo,Hanamoto, Takeshi
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p. 1090 - 1091
(2007/10/02)
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- Electrosyntheses of disaccharides from phenyl or ethyl 1-thioglycosides
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Constant current electrolyses of the glycosyl donors phenyl and ethyl 2,3,4,6-tetra-O-benzyl-1-thio-β-D-glucopyranoside in dry acetonitrile in the presence of various primary and secondary sugar alcohols, performed in an undivided cell, gave β-linked disaccharide derivatives selectively in good yields.Phenyl 2,3,4,6-tetra-O-benzoyl-1-thio-β-D-glucopyranoside gave the β-glucosides exclusively in good to moderate yields.
- Mallet, Jean-Maurice,Meyer, Gilbert,Yvelin, Frederic,Jutand, Anny,Amatore, Christian,Sinay, Pierre
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p. 237 - 246
(2007/10/02)
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- Direct Elaboration of Pent-4-enyl Glycosides Into Disaccharides
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Pent-4-enyl glycosides, on treatment with halonium ions, become chemospecifically activated so that coupling with partially protected monosaccharides can be effected, leading to the in situ formation of disaccharides.
- Fraser-Reid, Bert,Konradsson, Peter,Mootoo, David R.,Udodong, Uko
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p. 823 - 825
(2007/10/02)
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