- Efficient synthesis of thioglycosides via a Mitsunobu condensation
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Thioglycosides were synthesised from 1-thiosugars and a series of alcohols under Mitsunobu conditions using 1,1'-(azodicarbonyl)dipiperidine and trimethylphosphine. The conditions were found to be compatible with a wide range of functionalities and protec
- Falconer, Robert A.,Jablonkai, Istvan,Toth, Istvan
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- A NEW, STEREOSELECTIVE SYNTHESIS OF METHYL 1,2-TRANS-1-THIOGLYCOSIDES
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Per-O-acetylated glycopyranoses were converted by methylthiotrimethylsilane in the presence of boron trifluoride or trimethylsilyl trifluoromethanesulfonate to the corresponding methyl 1,2-trans-1-thioglycopyranosides in a highly stereoselective process.
- Pozsgay, Vince,Jennings, Harold J.
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- MANUFACTURE OF LACTO-N-TETRAOSE
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The present invention relates to the synthesis of the tetrasaccharide of formula (I) and novel intermediates used in the synthesis.
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Page/Page column 54
(2012/12/13)
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- Indium(III) triflate: A highly efficient catalyst for reactions of sugars
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Indium(III) trifluoromethanesulfonate has been found to be extremely efficient in catalyzing acyl transfer reactions of various carbohydrates and their derivatives. Selective acetolyses of certain benzyl ethers/isopropylidene acetals of sugars have been possible using In(OTf)3 in Ac2O (neat). Reaction of the per-O-acetate of 2-deoxy-2-phthalimido-D-glucose with benzyl mercaptan in the presence of In(OTf)3 led to the formation of the corresponding thioglycoside in high yield. Facile formation and hydrolysis of the isopropylidene and benzylidene acetals of various carbohydrates have also been achieved very efficiently in the presence of In(OTf)3. The results show great promise for In(OTf)3 in synthetic carbohydrate chemistry.
- Giri, Santosh Kumar,Verma, Monika,Kartha, K. P. Ravindranathan
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scheme or table
p. 464 - 478
(2009/04/06)
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- Modified one-pot protocol for the preparation of thioglycosides from unprotected aldoses via S-glycosyl isothiouronium salts
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An efficient one-pot protocol for the direct preparation of thioglycosides starting from unprotected reducing sugars via S-glycosyl isothiouronium salts is reported. In this one-pot methodology, BF3·OEt2 has been used as a general catalyst for both per-O-acetylation of sugars and conversion of sugar per-O-acetates into S-glycosyl isothiouronium salts, which was allowed to react with alkylating agents in the presence of a base to furnish thioglycosides in excellent yield. Copyright Taylor & Francis, Inc.
- Tiwari, Pallavi,Agnihotri, Geetanjali,Misra, Anup Kumar
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p. 723 - 732
(2007/10/03)
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- Streamlined synthesis of per-O-acetylated sugars, glycosyl iodides, or thioglycosides from unprotected reducing sugars
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Solvent-free per-O-acetylation of sugars with stoichiometric acetic anhydride and catalytic iodine proceeds in high yield (90-99%) to give exclusively pyranose products as anomeric mixtures. Without workup, subsequent anomeric substitution employing iodine in the presence of hexamethyldisilane (i.e., TMS-I generated in situ) gives the corresponding glycosyl iodides in 75-95% isolated yield. Alternatively, and without workup, further treatment with dimethyl disulfide or thiol (ethanethiol or thiocresol) gives anomerically pure thioglycosides in more than 75% overall yield.
- Mukhopadhyay, Balaram,Kartha, K.P. Ravindranathan,Russell, David A.,Field, Robert A.
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p. 7758 - 7760
(2007/10/03)
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- Iodine and its interhalogen compounds: Versatile reagents in carbohydrate chemistry v. synthesis of 1,2-trans-linked 1-thioglycosides from the per-o-acetylated glycoses
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Treatment of per-O-acetylated mono- and di-saccharides with (alkyl/arylthio)trimethylsilane and iodine at ambient temperature results in the formation of the corresponding 1,2-trans-1-thioglycosides in very high yield. In the case of higher boiling thiols such as ethanethiol, the reaction can be effectively carried out in the presence of the thiol itself instead of the silylated derivative, but the reaction is not stereospecific. Moreover, in the latter reactions a portion of the starting material remains unchanged even on prolonged reaction. With β-D-glucose pentaacetate (11) as the starting material, its epimerisation occurred during the reaction and therefore the recovered starting material was of α-D-configuration. In addition, the methyl disulphide-hexamethyldisilane system has been found to serve as an effective and cheaper alternative to the expensive (methylthio)-trimethylsilane.
- Kartha, K. P. Ravindranathan,Field, Robert A.
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p. 693 - 702
(2007/10/03)
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- Reaction of sugar thiocyanates with Grignard reagents. New synthesis of thioglycosides
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Glycosyl thiocyanates having hydroxyl groups protected with acetyl or benzoyl groups react readily at -40°C with Grignard reagents to afford the corresponding alkyl or aryl thioglycosides in good yields. Monosaccharide derivatives having the SCN grouping at other positions form under similar conditions thioethers. Axial thiocyanates do not react. Elevated temperatures induce side reactions leading to mercaptans.
- Pakulski, Zbigniew,Pierozynski, Donat,Zamojski, Aleksander
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p. 2975 - 2992
(2007/10/02)
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- SYNTHESIS OF A SULFATED GLYCOPEPTIDE CORRESPONDING TO THE CARBOHYDRATE-PROTEIN LINKAGE REGION OF PROTEOGLYCANS: β-D-GlcA-(1->3)4)>-β-D-Gal-(1->3)-β-D-Gal-(1->4)-β-D-Xyl-(1->3)-Ser
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A sulfated glycotetraosyl serin 4 was synthesized in a stereocontrolled manner by employing a key glycotetraosyl donor 7 and a serine derivative 6.
- Goto, Fumitaka,Ogawa, Tomoya
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p. 5099 - 5102
(2007/10/02)
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- Synthesis of Oligosaccharides Corresponding to the Common Polysaccharide Antigen of Group B Streptococci
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To facilitate mapping of the immunodominant region of the common polysaccharide antigen of group B streptococci, tetrasaccharide 1-O--α-rhamnopyranosyl>-D-glucitol (2) was synthesized in a stepwise fasion
- Pozsgay, Vince,Jennings, Harold J.
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p. 4042 - 4052
(2007/10/02)
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- Synthesis of a di-, tri-, and tetra-saccharide unit of the group B streptococcal common antigen.
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Condensation of methyl 2,3-O-isopropylidene-alpha-L-rhamnopyranoside with methyl 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-1-thio-beta-D-glucopyranoside activated by nitrosyl tetrafluoroborate gave an excellent yield of the protected disaccharide 9, which was transformed into glycosyl acceptor 11. Methyl 2,3,4,6-tetra-O-acetyl-1-thio-beta-D-galactopyranoside, obtained from D-galactose penta-acetate and methyl trimethylsilyl sulfide, under catalysis by boron trifluoride etherate, was converted into glycosyl donor 25, which was condensed with 11 under halide-ion catalysis to give the trisaccharide derivative 26. Rhamnosylation with 28 of 27, obtained by selective deprotection of 26, gave the protected tetrasaccharide 29. Deprotection of 10, 26, and 29 gave di- (2), tri- (3) and tetra-saccharide (4) methyl glycosides which form part of the group-specific polysaccharide antigen of Group B Streptococci.
- Pozsgay,Jennings
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- Total synthesis of globotriaosyl-E and Z-ceramides and isoglobotriaosyl-E-ceramide.
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Stereoselective, total synthesis of O-alpha-D-galactopyranosyl-(1----4) -O-beta-D-galactopyranosyl-(1----4)-O-beta-D-glucopyranosyl-(1----1)-N -tetracosanoyl-[2S,3R,4E (and 4Z)]-sphingenine and O-alpha-D -galactopyranosyl-(1----3)-O-beta-D-galactopyranosyl-(1----4)-O-beta-D -glucopyranosyl-(1----1)-N-tetracosanoyl-(2S,3R,4E)-sphin gen ine was achieved by using O-(2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl) -(1----4)-O-(2,3,6-tri-O-acetyl-beta-D-galactopyranosyl)-(1----4)-2,3,6- tri-O-acetyl-alpha-D-glucopyranosyl trichloroacetimidate, O-(2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl) -(1----4)-O-(2,3,6-tri-O-acetyl-beta-D-galactopyranosyl)-(1----4)-2,3,6- tri-O-acetyl-alpha (and beta)-D-glucopyranosyl fluoride, and O-(2,3,4,6-tetra-O-acetyl-alpha-D -galactopyranosyl)-(1----3)-O-(2,3,6-tri-O-acetyl-beta-D-galactopyran osyl)-(1----4)-2,3,6-tri-O-acetyl-alpha-D-glucopyranosyl trichloroacetimidate.
- Koike,Sugimoto,Sato,Ito,Nakahara,Ogawa
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p. 189 - 208
(2007/10/02)
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- LINOMYCIN ANALOGUES. II. CHAIN EXTENSION OF METHYL-6-ALDEHYDO-3,4-O-ISOPROPYLIDENE-1-THIO-β-D-GALACTO-1,5-PYRANOSIDE
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Synthesis of methyl 2,3,4,6-tetra-O-acetyl-1-thio-α-D-galactopyranoside and its β-anomer (3 and 4) from the 2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl bromide via the isothiouronium salt in HMPT involved a considerable increase in the proportion of the α-anomer.Deacetylation of (3 and 4) with sodium methoxide yielded 5 and 6 respectively.Conversion of 6 into corresponding 3,4-isopropylidene derivative (7) followed by oxidation with Collin reagent gave the aldehydo-sugar (8) which when reacted with the stabilized phosphorane led in the excellent yield to the Z-unsaturated bromo-sugar (9).
- Tronchet, Jean M. J.,Massoud, Mohamed A. M.
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p. 1265 - 1269
(2007/10/02)
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- A Through-process for the Preparation of Methyl Per-O-acetyl 1-Thio-glycosides from Aldoses
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D-Glucose, D-galactose, D-mannose, D-xylose, L-arabinose, L-fucose, L-rhamnose, maltose, cellobiose, lactose, D-glucosamine, D-galactosamine, and D-mannosamine were converted into the corresponding methyl per-O-acetyl 1-thioglycopyranosides by way of a three-step (acetobromination, methylthioation, and acetylation) through-process in a single vessel.
- Koto, Shinkiti,Yoshida, Toyosaku,Takenaka, Kazuhiro,Zen, Shonosuke
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p. 3667 - 3668
(2007/10/02)
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