Showing papers on "Glucal published in 2001"
TL;DR: A variety of functionalized C -pseudoglycals (pseudoglobal C -glycosides or C -hex-2-enopyranosides) have been obtained in excellent yields and stereoselectivity from the Yb(OTf) 3 -catalyzed reaction of tri-O -acetyl glucal with silylated nucleophiles such as allyl and propargyl silanes and silyl enol ethers.
64 citations
TL;DR: The two electrophilic Vilsmeier-Haack reagents POCl3.DMF 2 or (CF3SO2)2O mediate the one-step and selective conversion of O-triethylsilyl (O-TES), O-tert-butyldimethylsallyl ( O-TBDMS, O- tert- butyldiphenylsilyL (O)-TBDPS, and O- triisop
Abstract: The two electrophilic Vilsmeier−Haack reagents POCl3·DMF 2 or (CF3SO2)2Ο·DMF 3 mediate the one-step and selective conversion of O-triethylsilyl (O-TES), O-tert-butyldimethylsilyl (O-TBDMS), O-tert-butyldiphenylsilyl (O-TBDPS), and O-triisopropylsilyl (O-TIPS) ethers of d-glucal to the corresponding C(6)-O-formates.
42 citations
TL;DR: In this article, a synthesis of apicularen analogue (−)-4 in 18 steps from d -glucal was reported, which constitutes a formal total synthesis of this potent naturally occurring anti-cancer agent.
39 citations
TL;DR: Direct synthetic access to 2-hydroxy-alpha-mannopyranosides from glucal donors is accomplished via a one-pot stereoselective oxidative glycosylation reaction, employing the reagent combination of dibenzothiophene bis(triflate) and dibenza-5-oxide.
34 citations
TL;DR: In this paper, 1,6:2,3-Dianhydro-β-d -glucopyranose and its 3-alkylated derivatives were prepared from d-glucal in one pot with overall isolated yields of 60-70%.
33 citations
TL;DR: In this article, the Mitsunobu reaction was used for the configuration inversion at C-6 by the sugar−non-sugar−sugar strategy, and the synthetic argentilactone has been tested against Leishmania mexicana.
30 citations
TL;DR: In this paper, the triisopropylsilyl and/or isopropyldene-protected 1-lithio-d -glucals were obtained from stannylated precursors 5 and 6 to hexacarbonyl chromium followed by methylation, and the conformation of the glucal moiety in the carbene ligand and in the chroman skeleton was controlled by the nature of the protective groups.
26 citations
TL;DR: A facile synthesis of anomerically pure phthalimidomethyl 2,3,4,6-tetra-O -acetyl- and 2, 3,di-O-acetyl 4,6,di O -benzoyl-α-d -mannopyranosides (6 and 9b ) starting from N -hydroxymethylphthalimide and tri-O −acetyl d -glucal is described as mentioned in this paper.
26 citations
TL;DR: This compound served as the common precursor for three [13C]methyl 2-deoxy-beta-D-glucopyranoside derivatives: (2-[15N]trifluoroacetyl-), (2]-15N], (2]:15N, and (2-azido-).
22 citations
TL;DR: The treatment of 2,3,4,6-tetra-O-acetyl-1,5-anhydro-D-arabino-hex-1-enitol with azidotrimethylsilane by the aid of a catalytic amount of Yb(OTf).
20 citations
TL;DR: In this article, the β-glycosidase from the archaeon Sulfolobus solfataricus (Ssβ-gly) has been used for an efficient synthesis of β-2-deoxyglucosides and for stereochemical studies of the reactions of glucal in the presence of alkyl and pyranosidic acceptors.
Abstract: The hyperthermophilic member of family 1 of the glycosyl hydrolases, the β-glycosidase from the archaeon Sulfolobus solfataricus (Ssβ-gly), has been used for an efficient synthesis of β-2-deoxyglucosides and for stereochemical studies of the reactions of glucal in the presence of alkyl and pyranosidic acceptors. Protonation of the double bond of glucal resulting in the equatorially disposed proton was observed and an indication of the protonating amino acid in the active site was obtained by the use of a mutant enzyme. The regioselectivity in the formation of β-2-deoxyglucosides of pyranosidic acceptors is different from that reported for mesophilic biocatalysts.
TL;DR: In this paper, an eight-step sequence that features a stereoselective methyl Grignard addition to an iodo-hexenulose was used to convert glucal to epoxy allylic alcohol 4.
TL;DR: In the presence of a Lewis acid, ArSCl adducts of tri-O -benzyl-d -glucal react with vinyl ethers to form cyclic five-membered sulfonium salt intermediates as discussed by the authors.
TL;DR: It is confirmed that the proposed solution to the £1.3bn debt problem will not be implemented in time for the Olympics.
Abstract: 前報に続き, アルトラクトン, イソアルトラクトン, 5-ヒドロキシゴニオタラミンの両鏡像体の合成を行った. トリ-O-アセチル-D-グルカールから得られたアセタールに必要な側鎖を延長後, アセタールをラクトンに導き, 立体化学を修飾することにより, 5-ヒドロキシゴニオタラーンの両鏡像体を得た. 更にエポキシ化・酸処理によってアルトラクトンとイソアルトラクトンの両鏡像体を合成した. アルトラクトンの6種の異性体の生物活性を測定した結果, 殺ブラインシュリンプテストでは, 3位の水酸基が covex 面にある (立体的に空いている) 化合物の活性が強かった. レタス発芽においては (2S,3S) の立体を有する化合物が発芽, 特に根の伸長に強い阻害効果を示した.
TL;DR: The two electrophilic Vilsmeier−Haack reagents POCl3·DMF 2 or (CF3SO2)2Ξ−DMF 3 as discussed by the authors mediate the one-step and selective conversion of O-triethylsilyl (O-TES), O-tert-butyldimethylmethylmixtures (OTBDMS), and O-TBDPS to the corresponding C(6)-O-formates.
Abstract: The two electrophilic Vilsmeier−Haack reagents POCl3·DMF 2 or (CF3SO2)2Ο·DMF 3 mediate the one-step and selective conversion of O-triethylsilyl (O-TES), O-tert-butyldimethylsilyl (O-TBDMS), O-tert-butyldiphenylsilyl (O-TBDPS), and O-triisopropylsilyl (O-TIPS) ethers of d-glucal to the corresponding C(6)-O-formates.
TL;DR: A facile synthesis of anomerically pure phthalimidomethyl 2,3,4,6-tetra-O -acetyl- and 2, 3,di-O-acetyl 4,6,di O -benzoyl-α-d -mannopyranosides (6 and 9b ) starting from N -hydroxymethylphthalimide and tri-O −acetyl d -glucal is described as discussed by the authors.
Abstract: A facile synthesis of anomerically pure phthalimidomethyl 2,3,4,6-tetra- O -acetyl- and phthalimidomethyl 2,3-di- O -acetyl-4,6-di- O -benzoyl-α- d -mannopyranosides ( 6 and 9b ) starting from N -hydroxymethylphthalimide and tri- O -acetyl- d -glucal is described. Compounds 3 , 6 , 8 , 9a and 9b have been tested for their hypolipidemic activity in mice. All these compound showed significant reduction of plasma cholesterol and triglyceride levels. Compound 9b has been found to possess the highest activity.
TL;DR: In this paper, a synthesis of apicularen analogue (−)-4 in 18 steps from d -glucal was reported, which constitutes a formal total synthesis of this potent naturally occurring anti-cancer agent.
Abstract: A synthesis of apicularen analogue (−)-4 in 18 steps from d -glucal is reported. As (+)-4 has been converted into apicularen A in 8 steps, this constitutes a formal total synthesis of this potent naturally occurring anti-cancer agent.
01 Jan 2001
TL;DR: The structure was determined to be a polysaccharide consisting of 2-halo-2-deoxy-alpha-D-mannoside units, indicating that the polymerization proceeded via stereoregular glycosylation manner.
Abstract: In this letter, we report synthesis of branched polysaccharide 2 by glycosylation of glucal-type monomer 1 with two free hydroxy groups at position 3 and 4. Monomer 1 polymerized with N-halosuccinimide promoter in acetonitrile solvent at room temperature--50 degrees C. The product was isolated as a petroleum ether insoluble fraction. The structure was determined by 1H and 13C NMR spectra as well as elemental analysis to be a polysaccharide consisting of 2-halo-2-deoxy-alpha-D-mannoside units, indicating that the polymerization proceeded via stereoregular glycosylation manner. The molecular weights determined by GPC with DMF were 3,300-4,000. The degree of branching was estimated by the NMR data of the product from the reaction of 2 with 3,5-dinitrobenzoyl chloride.
TL;DR: In the presence of a Lewis acid, ArSCl adducts of tri-O -benzyl-d -glucal react with vinyl ethers to form cyclic five-membered sulfonium salt intermediates.
Abstract: In the presence of a Lewis acid, ArSCl adducts of tri- O -benzyl- d -glucal react with vinyl ethers to form cyclic five-membered sulfonium salt intermediates. The latter are capable of reacting with TMSCN and Grignard reagents furnishing exclusively 2- S -(aryl)-2-thio-β- C - d -glucopyranosides. The one-pot reaction also proceeds with high stereoselectivity of C–C bond formation in the lateral chain providing exclusively or predominantly C -glycosides with ( S )-configuration of the chiral center in the lateral chain.
TL;DR: In this article, the authors used a Carlo2Erba microanalyser for elemental analyses on silica gel 60 A CC (2302400 mesh) and performed a flash column chromatography with silica girders.
Abstract: solutions on an FT-spectrometer. Elemental analyses weredetermined by our university9s Scientific Service using aCarlo2Erba Microanalyser. Flash column chromatography wasperformed with silica gel 60 A CC (2302400 mesh). Preparativethin layer chromatography was performed on silica gel 60. Solventswere distilled at atmospheric pressure before use. Benzene was driedby distillation from Na ribbon and stored over 4A˚ molecular sievesand under argon. Dry ether was obtained by distillation, undernitrogen, from sodium benzophenone ketyl. Other solvents werepurified and dried by standard procedures. All the reactions werecarried out under an argon atmosphere using standard syringetechniques.
TL;DR: In this paper, a 2-vinyl glucal derivative was synthesized by Wittig-type methylenation of pyranosidic conjugated enals, derived from glucal, galactal and lactal.
Abstract: Monosaccharidic and disaccharidic 2-C-(β-methyl)methylene glycosides were synthesized by an electrophilic conjugate addition reaction of ROH-type compounds in the presence of Ph3P+H Br− to 2-ethenyl-3,4,6-tri-O-benzyl-D-glucal 1, functioning as a model glycosyl donor. This 2-vinyl glucal derivative represents a series of 2-vinyl and 2-butadienyl glycals, prepared by Wittig-type methylenation of pyranosidic conjugated enals, derived from glucal, galactal and lactal. The exo-(β-methyl)methylene group paves the way for further chemical transformations.
TL;DR: In this article, the chiral synthesis of the fully functionalized CD ring unit paclitaxel 3 is described; the three component coupling reaction of a cyclohexenone derived from D-glucal by way of Ferrier's carbocyclization with vinyl cuprate and formaldehyde effectively constructed the carbon framework of 3.
Abstract: The chiral synthesis of the fully functionalized CD ring unit
of paclitaxel 3 is described; the three component coupling reaction of a
cyclohexenone derived from D-glucal by way of Ferrier’s
carbocyclization with vinyl cuprate and formaldehyde effectively
constructed the carbon framework of 3.