- Palladium(ii)-assisted activation of thioglycosides
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Described herein is the first example of glycosidation of thioglycosides in the presence of palladium(ii) bromide. While the activation with PdBr2alone was proven feasible, higher yields and cleaner reactions were achieved when these glycosylat
- Escopy, Samira,Singh, Yashapal,Demchenko, Alexei V.
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p. 2044 - 2054
(2021/03/16)
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- Chemoselective glycosylations using sulfonium triflate activator systems
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A novel chemoselective glycosylation sequence is described that employs the recently developed BSP/Tf2O and DPS/Tf2O reagent systems to activate thioglycosides. In the first glycosylation event a relatively armed thioglycoside is activated with the BSP/Tf2O activator system and condensed with an acceptor thioglycoside to yield the thiodisaccharide, which is activated with the more potent DPS/Tf2O activator in the next glycosylation event. Quenching of (N-piperidino)phenyl(S- thiophenyl)sulfide triflate, which is formed upon activation of the first thioglycoside, with triethyl phosphite is crucial for a productive glycosylation.
- Codée, Jeroen D.C.,Van Den Bos, Leendert J.,Litjens, Remy E.J.N.,Overkleeft, Herman S.,Van Boeckel, Constant A.A.,Van Boom, Jacques H.,Van Der Marel, Gijs A.
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p. 1057 - 1064
(2007/10/03)
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- Catalytic and stereoselective glycosylation with glucosyl thioformimidates
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A novel and efficient glycosyl donor having a p- trifluoromethylbenzylthio-N-p-trifluoromethylphenylformimidate group at an anomeric position is easily prepared by the addition of anomeric hydroxy group of 2,3,4,6-tetra-O-benzyl-α,β-D-glucopyranose to p-t
- Chiba, Hiroyuki,Funasaka, Setsuo,Mukaiyama, Teruaki
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p. 1629 - 1644
(2007/10/03)
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- Protic acid catalyzed stereoselective glycosylation using glycosyl fluorides
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A catalytic and stereoselective glycosylation of various glycosyl acceptors, such as methyl glycosides, thioglycosides, or a disarmed glycosyl fluoride, with benzyl-protected armed glycosyl fluoride was successfully carried out by using various protic acids in the presence of MS 5A. In the cases when trifluoromethanesulfonic acid (TfOH) or perchloric acid (HClO4) was used in diethyl ether (Et2O), α-glycosides were obtained as major products, while β-stereoselectivity was observed when tetrakis(pentafluorophenyl)boric acid [HB(C6F5)4] was used in a mixed solvent of trifluoromethylbenzene (BTF)-pivalonitrile (tBuCN) = 5:1. Stereoselectivity of this glycosylation was controlled by the properties of counter anions of the catalyst as well as by those of solvents. Also, one-pot trisaccharide synthesis was performed by successive addition of NIS and third-sugar to afford Glcα or β1-6Glcβ1-6Glc and Glcα or β1-6GlcNβ1-6Glc in excellent yields.
- Jona, Hideki,Mandai, Hiroki,Chavasiri, Warinthorn,Takeuchi, Kazuya,Mukaiyama, Teruaki
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p. 291 - 309
(2007/10/03)
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- A catalytic and stereoselective glycosylation with glucopyranosyl fluoride by using various protic acids
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A catalytic and stereoselective glycosylation with glucosyl fluoride was effectively performed by using a catalytic amount of various protic acids. When the glycosylation was carried out, for example, using perchloric acid (HClO4) in diethyl et
- Jona, Hideki,Mandai, Hiroki,Mukaiyama, Teruaki
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p. 426 - 427
(2007/10/03)
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- Chemoselective Glycosylations (Part 1): Differences in Size of Anomeric Leaving Groups can be Exploited in Chemoselective Glycosylations
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We have developed a novel chemoselective glycosylation strategy.This glycosylation strategy is based on the fact that the glycosyl reactivity of an anomeric thiol group can be control by the bulkiness of this group whereby we have produced a new range of
- Boons, Geert-Jan,Geurtsen, Richard,Holmes, Duncan
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p. 6325 - 6328
(2007/10/02)
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- AN EFFICIENT THIOGLYCOSIDE-MEDIATED FORMATION OF α-GLYCOSIDIC LINKAGES PROMOTED BY IODONIUM DICOLLIDINE PERCHLORATE
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Chemospecific glycosidation of partially-benzoylated thioglycosides ("disarmed" acceptors) with perbenzylated thioglycosides ("armed" donors) can be realized in the presence of the promotor iodonium dicollidine perchlorate.The reaction results predominantly in the formation of α-linked saccharides and is compatible with the use of various protecting groups.
- Veeneman, G. H.,Boom, J. H. van
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p. 275 - 278
(2007/10/02)
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