Reciprocal Donor Acceptor Selectivity (RDAS) and Paulsen’s Concept of “Match” in Saccharide Coupling

Fraser‐Reid, Bert; López, J. Cristóbal; Gómez, Ana M.; Uriel, Clara

doi:10.1002/ejoc.200300689

Cited by 75 publications

(48 citation statements)

References 47 publications

(32 reference statements)

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“…[119a] Rationalization of these regioselectivities led to the birth of the concept of reciprocal donor-acceptor selectivity (RDAS), [120] which is related to the concept of donor/acceptor matching introduced by Paulsen. [5] The versatility of NPOE donors was further demonstrated recently in the efficient assembly of a pentadecamannan.…”

Section: 2-orthoesters Of Aldosesmentioning

confidence: 99%

New Principles for Glycoside‐Bond Formation

2009

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Increased understanding of the important roles that oligosaccharides and glycoconjugates play in biological processes has led to a demand for significant amounts of these materials for biological, medicinal, and pharmacological studies. Therefore, tremendous effort has been made to develop new procedures for the synthesis of glycosides, whereby the main focus is often the formation of the glycosidic bonds. Accordingly, quite a few review articles have been published over the past few years on glycoside synthesis; however, most are confined to either a specific type of glycoside or a specific strategy for glycoside synthesis. In this Review, new principles for the formation of glycoside bonds are discussed. Developments, mainly in the last ten years, that have led to significant advances in oligosaccharide and glycoconjugate synthesis have been compiled and are evaluated.

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Section: 2-orthoesters Of Aldosesmentioning

confidence: 99%

New Principles for Glycoside‐Bond Formation

2009

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“…This effect could explain the lower degree of glycosylation of hydroxyl groups with either no possible or favorable hydrogen bond assistance described in the literature. That could be the case of the higher ratio of glycosylation of hydroxyl groups at C3 position even being the most hindered one, compared to OH-2 in α-altrose diol acceptor derivatives described by Fraser-Reid et al [66]. This fact could also explain the glycosylation tendency of the axial hydroxyl group at C1 versus C2 in D-chiro-inositol 1,2-syn diol acceptors [54].…”

Section: Superarmed Glycosyl Donors In Glycosylation Reactionsmentioning

confidence: 83%

“…The authors observed that when differently protected 1,2-diols, derived from both chiroinositol enantiomers, are used as acceptors, both the absolute configuration of the acceptor as well as the nature of the donor's and acceptor's protecting groups plays a key role in the regiochemistry of the coupling. A few examples of regioselective glycosylation of 1,2-cis-axial/equatorial [51,62,63] and 1,2-trans-diequatorial diols [51,53,64] have been described, and the influence of the donor's protecting groups on the regiochemistry of polyol glycosylation has been investigated [65,66]. A notable example of regioselective glycosylation of 1,2-trans-diequatorial diol is the virtually complete regioselective galactosylation of the OH-4 group of p-methoxyphenyl 6-O-benzyl-2-deoxy-2-tetrachlorophthalimido-β-D-glucopyranoside 137 (Fig.…”

Section: Regio-and Stereoselectivity In Glycosylationmentioning

confidence: 99%

Armed-Disarmed Concept in the Synthesis of Glycosidic Bond

Miljković

2013

Electrostatic and Stereoelectronic Effects in Carbohydrate Chemistry

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-Reid et al. reported [1] that n-pentenyl glycosides undergo chemospecific cleavage 1 ! 2 ! 3, with N-bromosuccinimide under conditions that leave a wide variety of other protecting groups unaffected ( Fig. 5.1).According to the proposed mechanism ( Fig. 5.1), the addition of water to the reaction mixture will lead to hydrolysis but the addition of alcohol or another sugar having a free hydroxyl group will lead to the formation of glycoside or a disaccharide. In the course of these studies, Fraser-Reid et al. [1] observed that sugar molecules having an acyloxy group at the C2 carbon (6 in Fig. 5.2) hydrolyzed much more slowly than if they had an alkoxy group (7 in Fig. 5.2). This observation suggested that the n-pentenyl glycoside could be made more or less reactive (it could be armed or disarmed) by the type of protecting group placed on the C2 oxygen.The ability of the C2 acyloxy group to disarm the n-pentenyl glycoside was rationalized as shown in Fig. 5.3. Thus, it can be assumed that the cyclic halonium ions 8 and 9 are formed reversibly [2] and that the electron density on the glycosidic oxygen is depleted in 2-O-acyl derivatives so that nucleophilic attack of this oxygen on the halonium ion is less favored than in the 2-O-alkyl counterpart 9. The reason for this is that the electron-withdrawing group at the C2 carbon makes the C2 carbon slightly positively charged so that the formation of another positive charge at the C1 carbon is not a favorable process [there cannot exist two positive charges on two neighboring carbons (C1 and C2) (Fig. 5.3).].Consequently, the armed glycosyl donors react with electrophiles faster than the disarmed ones, and therefore in a solution containing both an armed and disarmed glycosyl donor molecules, whereby disarmed glycosyl donor molecules have one free hydroxyl group, the reaction with an electrophile will result in crosscoupling and not self-coupling, i.e., an armed glycosyl donor will react with the disarmed one, whereas a disarmed donor will not react with itself [3] as illustrated in Fig. 5.5. The promoters for the activation of n-pentenyl group [4,5] are iodonium dicollidine perchlorate (IDCP) and N-iodosuccinimide/triethylsilyl triflate (NIS/Et 3 SiOTf).M. Miljkovic, Electrostatic and Stereoelectronic Effects in Carbohydrate Chemistry,

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“…The Reciprocal Donor Acceptor Selectivity (RDAS) definition has been recently introduced. 24 In our laboratory, we have extensively employed the trichloroacetimidate method 25 for β-galactofuranosyl linkages construction 26,27 allowing the synthesis of internal D-Galf-containing oligosaccharides. 28,29 In order to study this methodology in the α-galactofuranosyl linkage construction, a straightfoward synthesis of 1 is needed, that after imidate activation, would allow further glycosylation studies with different acceptors.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of 2,3,5,6-tetra-O-benzyl-D-galactofuranose for α-glycosidation

Gola¹,

Libenson²,

Gandolfi-Donadío³

et al. 2006

Arkivoc

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Dedicated to Prof. Rosa M. de Lederkremer on her 70th anniversary AbsractThe synthesis of 2,3,5,6-tetra-O-benzyl-D-galactofuranose, a useful compound for α-glycosylation studies, is described. Direct anomeric O-alkylation of galactose was employed for alpha-allylation to yield pure allyl α-D-galactofuranoside, which is a versatile precursor for the synthesis of galactofuranose-containing oligosaccharides. Allyl removal of the benzylated galactofuranosyl derivative was performed using palladium (II) chloride as catalyst.

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Reciprocal Donor Acceptor Selectivity (RDAS) and Paulsen’s Concept of “Match” in Saccharide Coupling

Cited by 75 publications

References 47 publications

New Principles for Glycoside‐Bond Formation

New Principles for Glycoside‐Bond Formation

Armed-Disarmed Concept in the Synthesis of Glycosidic Bond

Synthesis of 2,3,5,6-tetra-O-benzyl-D-galactofuranose for α-glycosidation

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