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Mong, Kwok-Kong Tony; Wong, Chi‐Huey

doi:10.1002/1521-3757(20021104)114:21<4261::aid-ange4261>3.0.co;2-3

Cited by 39 publications

(16 citation statements)

References 10 publications

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“…These signals are presumably generated from the a-glycosyl imidate 64. [25] As the real-time NMR spectroscopic study provided evidence for the presence of the a-glycosyl imidate, it is reasonable to propose the formation of a-/b-glycosyl imidates in DMF-modulated glycosylations. Following the addition of acceptor 58, the signals stemming from imidate 64 vanished, and another two sets of signals emerged.…”

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confidence: 95%

Dimethylformamide: An Unusual Glycosylation Modulator

et al. 2011

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A simple solution: When N,N‐dimethylformamide was used to direct the stereochemical course of glycosylation reactions, 1,2‐cis glycosylation products were formed with excellent selectivity. A straightforward highly α‐stereoselective glycosylation involving preactivation (see scheme) should find broad application and be especially useful for sequential glycosylation reactions to form oligosaccharides. LG=leaving group.

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confidence: 95%

Dimethylformamide: An Unusual Glycosylation Modulator

et al. 2011

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“…Lewis Y can be obtained through one-pot coupling of two fucosyl and two lactosaminyl building blocks (Fig. 35.14 b) [149]. These new synthetic strategies could be used in the rapid synthesis of antigen analogues, including the aglycon moieties, for identification of the optimal structures to be used in vaccine development.…”

Section: Programmable One-pot Oligosaccharide Synthesismentioning

confidence: 66%

Carbohydrate‐Based Drug Discovery in the Battle against Bacterial Infections: New Opportunities Arising from Programmable One‐Pot Oligosaccharide Synthesis

Ritter¹,

Wong

2003

Carbohydrate‐Based Drug Discovery

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“…For the synthesis of 28 , 2‐azido‐2‐deoxy thioglucoside 26 in CH 2 Cl 2 solution (40 mM) was firstly glycosylated with thiofucoside 25 to furnish a disaccharide intermediate (Scheme ) 30. Being a deoxy sugar, the thiofucoside 25 is far more reactive than thioglucoside 26 ; as a result, it is activated preferentially in the presence of 25 22a,b. Upon completion of the glycosylation of 26 , CH 3 CN and EtCN were added to the mixture to provide LCG conditions for glycosylation of the subsequently added acceptor 27 .…”

Section: Methodsmentioning

confidence: 99%

“…Regarding the synthesis of 32 , thiogalactoside 29 , thioglucoside 30 and lactoside 31 were required (Scheme ) 31. Thiogalactoside 29 was innately more reactive than 30 ;32 thus, glycosylation of 29 with 30 furnished a LacNAc intermediate 22a,b. After the completion of the first glycosylation, subsequent addition of the alkyl nitrile solvent mixture, lactoside 31 and NIS promoter furnished the desired tetrasaccharide 32 in 50% yield after chromatographic purification 33,34…”

Section: Methodsmentioning

confidence: 99%

Solvent Participation in a One‐Pot Glycosylation Strategy (SPOG)

et al. 2011

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Solvent participation in a one-pot glycosylation strategy (SPOG) was developed on the basis of the low concentration b-selective glycosylation method. This strategy enables the production of a b-glycosidic bond in a one-pot oligosaccharide synthesis without or with minimal use of any C-2 participating function.Keywords: low concentration glycosylation; nitriles; one-pot process; reactivity-based reaction; solvent participation Oligosaccharide synthesis involves the coupling of carbohydrate units in a regio-and stereospecific manner. [1,2] This process can be accelerated by a onepot glycosylation strategy [3] and automated solidphase synthesis.[4] One-pot glycosylation refers to cascade coupling of three or more carbohydrate units in one shot.[5] A key element in these reactions is the stereochemical control of glycosidic bond formation, which often relies on traditional methods. A point in case is the use of neighbouring group participation for the construction of a 1,2-trans b-glycosidic bond. [6] However, such an approach requires the selective introduction of a C-2 participating function and it occasionally suffers from side reactions that decreases the yield of glycosylations. [7,8] Although alternative methods are available, only few of them are adapted to one-pot oligosaccharide synthesis. [9,10] Recently, a low concentration b-selective glycosylation (LCG) method was developed.[11] This method makes use of: (i) a CH 2 Cl 2 /CH 3 CN/EtCN solvent system; (ii) low substrate concentrations (10-15 mM); and (iii) low reaction temperature (À70 to À60 8C) to construct the 1,2-trans b-glycosidic bond without reliance on any C-2 participating function. A search in the literature revealed that the solvent effect on reactivity of glycosyl donors has been explored for onepot oligosaccharide synthesis, but the participation effect of an alkyl nitrile solvent on one-pot glycosylation has not been investigated. [12,13] This lack of information motivated us to develop a new one-pot glycosylation strategy on the basis of the LCG method. As the participation effect of an alkyl nitrile solvent is explored, we coin this approach as a solvent participation in one-pot glycosylation (SPOG) strategy.According to the order of solvent addition, two SPOG procedures were studied (Figure 1). In the first procedure, all glycosylation steps are performed under LCG conditions. As such, oligosaccharides with 1,2-trans b-glycosidic bonds are prepared (Figure 1 a). [10] In the second procedure, CH 2 Cl 2 and a conventional substrate concentration are employed for the first glycosylation step. Upon completion of this reaction, calculated amounts of CH 3 CN and EtCN are added to the mixture providing the LCG conditions for the next glycosylation reaction (Figure 1 b). The merit of the second procedure is to allow adjustment of the solvent mixture for the construction of a-and b-glycosidic bonds.Before exploiting the SPOG procedures, it was crucial to know if the LCG method would apply to nonthioglycoside donors. Thus, perbenzyl thiog...

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Abstract: Die stereospezifische Synthese des Kohlenhydrat‐Haptens Lewis Y gelang durch eine Eintopfreaktion der drei Synthesebausteine 1–3, die anhand ihrer relativen Reaktivität (RR) für die Reaktion ausgewählt wurden.

Cited by 39 publications

References 10 publications

Dimethylformamide: An Unusual Glycosylation Modulator

Dimethylformamide: An Unusual Glycosylation Modulator

Carbohydrate‐Based Drug Discovery in the Battle against Bacterial Infections: New Opportunities Arising from Programmable One‐Pot Oligosaccharide Synthesis

Solvent Participation in a One‐Pot Glycosylation Strategy (SPOG)

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