13242-55-2Relevant academic research and scientific papers
Cyclization of N-(Tetra-O-acetyl-D-gluco- and D-mannopyranosyl)-pyridinium salts in a methanolic solution of sodium methylate
Skorupowa,Dmochowska,Madaj,Kasprzykowski,Sokolowski,Wisniewski
, p. 49 - 59 (1998)
N-(2,3,4,6-Tetra-O-acetyl-α-D-gluco-, β-D-gluco- and β-D-mannopyranosyl)-pyridinium salts were obtained and their structures were determined by 2D 1H NMR spectroscopy. The compounds obtained were treated with a methanolic solution of sodium methylate. The β-anomer of the D-gluco derivative cyclizes via Brigl's anhydride but the α anomer is competitively transformed according to the SN2 and SN1 mechanisms. The β-D-manno derivative does not cyclize under the conditions used. Comparison of the qualitative and quantitative results of the reaction studied enabled estimation of the influence of configuration at C-1 and C-2 on the course of cyclization. All product mixtures were separated by capillary gas chromatography (CGC) as exhaustively O-acetylated derivatives and their components were identified by coinjection with authentic materials.
A stepwise solvent-promoted SNi reaction of α-d- glucopyranosyl fluoride: Mechanistic implications for retaining glycosyltransferases
Chan, Jefferson,Tang, Ariel,Bennet, Andrew J.
, p. 1212 - 1220 (2012)
The solvolysis of α-d-glucopyranosyl fluoride in hexafluoro-2- propanol gives two products, 1,1,1,3,3,3-hexafluoropropan-2-yl α-d-glucopyranoside and 1,6-anhydro-β-d-glucopyranose. The ratio of these two products is essentially unchanged for reactions that are performed between 56 and 100 °C. The activation parameters for the solvolysis reaction are as follows: ΔH? = 81.4 ± 1.7 kJ mol -1, and ΔS? = -90.3 ± 4.6 J mol -1 K-1. To characterize, by use of multiple kinetic isotope effect (KIE) measurements, the TS for the solvolysis reaction in hexafluoro-2-propanol, we synthesized a series of isotopically labeled α-d-glucopyranosyl fluorides. The measured KIEs for the C1 deuterium, C2 deuterium, C5 deuterium, anomeric carbon, ring oxygen, O6, and solvent deuterium are 1.185 ± 0.006, 1.080 ± 0.010, 0.987 ± 0.007, 1.008 ± 0.007, 0.997 ± 0.006, 1.003 ± 0.007, and 1.68 ± 0.07, respectively. The transition state for the solvolysis reaction was modeled computationally using the experimental KIE values as constraints. Taken together, the reported data are consistent with the retained solvolysis product being formed in an SNi (DN? A Nss) reaction with a late transition state in which cleavage of the glycosidic bond is coupled to the transfer of a proton from a solvating hexafluoro-2-propanol molecule. In comparison, the inverted product, 1,6-anhydro-β-d-glucopyranose, is formed by intramolecular capture of a solvent-equilibrated glucopyranosylium ion, which results from dissociation of the solvent-separated ion pair formed in the rate-limiting ionization reaction (DN? + AN). The implications that this model reaction have for the mode of action of retaining glycosyltransferases are discussed.
AMINE-CATALYZED TRANSFORMATION OF ENOLIC NONENZYMIC BROWNING PRODUCTS, ISOMALTOL GLYCOPYRANOSIDES INTO 1,6-ANHYDRO-β-D-HEXOPYRANOSES
Goodwin, James C.
, p. 61 - 68 (1985)
The nonenzymic browning products, isomaltol D-galacto- and D-glucopyranosides, are transformed by 5:1 (v/v) triethylamine-pyrrolidine into 1,6-anhydro-β-D-galactopyranose (41percent) and 1,6-anhydro-β-D-glucopyranose (3percent), respectively.The amines, designed to simulate the amino functionality in proteins, peptides, and ammonia (eliminated by decomposition of amino acids, proteins, and peptides) relative to nonenzymic browning during the baking process, catalyzed the transformations through the production of alkoxide ions formed from deprotonation of the ring hydroxyl groups in 1 : 1 (v/v) aqueous ethanol.
Synthesis of 1,6-anhydro sugars catalyzed by silica supported perchloric acid
Chun, Yuexing,Yan, Shiqiang,Li, Xiangpeng,Ding, Ning,Zhang, Wei,Wang, Peng,Li, Ming,Li, Yingxia
experimental part, p. 6196 - 6198 (2011/12/01)
A new and efficient method for the preparation of 1,6-anhydro sugars using silica supported perchloric acid as a catalyst is described. The catalyst is heterogeneous and 1,6-anhydro sugars could be formed within a few minutes with good yields.
1,6-Anhydro-1-thio-β-D-glucopyranose (thiolevoglucosan) and the corresponding sulfoxides and sulfone
Budesinsky, Milos,Polakova, Jana,Hamernikova, Michaela,Cisarova, Ivana,Trnka, Tomas,Cerny, Miloslav
, p. 311 - 336 (2007/10/03)
Starting 1,2,3,4-tetra-O-acetyl-6-O-tosyl-β-D-glucopyranose (3) was converted into 2,3,4-tri-O-acetyl-1-thio-6-O-tosyl-β-D-glucopyranose (6) via intermediate glycosyl bromide 4 and S-thiouronium salt 5. Treatment of compound 6 with sodium methoxide gave 1,6-anhydro-1-thio-β-D-glucopyranose (thiolevoglucosan 2a). The isomeric sulfoxides 7 and 8 were prepared by selective oxidation of thiolevoglucosan 2a with hydrogen peroxide or 3-chloroperoxybenzoic acid. The structure of new compounds was confirmed by 1H and 13C NMR spectroscopy or by X-ray analysis; magnetic anisotropy of the sulfinyl and sulfonyl group has been discussed.
Ferric chloride: A mild and versatile reagent for the formation of 1,6-anhydro glucopyranoses
Miranda, Pedro O.,Brouard, Ignacio,Padrón, Juan I.,Bermejo, Jaime
, p. 3931 - 3934 (2007/10/03)
A novel method for the preparation of 1,6-anhydro glucopyranoses (mono- and disaccharides) utilizing anhydrous FeCl3 as Lewis acid is described. Treatment of methyl 6-O-benzyl and 6-O-p-methoxybenzyl-α/β D-glucopyranosides derivatives with FeCl3 in CH2Cl2 at room temperature and 40°C afforded 1,6-anhydro glucopyranosides in moderate to good yields, through a debenzylation and intramolecular glycosidation in one step. A plausible reaction pathway is proposed.
A practical large-scale access to 1,6-anhydro-β-D-hexopyranoses by a solid-supported solvent-free microwave-assisted procedure
Bailliez, Vincent,De Figueiredo, Renata M.,Olesker, Alain,Cleophax, Jeannine
, p. 1015 - 1017 (2007/10/03)
Microwave irradiation of 6-O-tosyl or 2,6-di-O-tosyl peracetylated hexopyranoses absorbed on basic alumina in a dry medium afforded the corresponding 1,6-anhydro-β-D-hexopyranoses. A direct access to 1,6:3,4-dianhydro-β-D-altropyranose (16) from D-glucose is also described.
Total synthesis of the antiallergic naphtho-α-pyrone tetraglucoside, cassiaside C2, isolated from Cassia seeds
Zhang, Zhaojun,Yu, Biao
, p. 6309 - 6313 (2007/10/03)
Toralactone 9-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl-(1→3)- P-D-glucopyranosyl-(1-6)-β-D-glucopyranoside (1, cassiaside C2), isolated from Cassia obtusifolia L. and showing strong antiallergic activity, was concisely synthesized employing glycosyl trifluoroacetimidates as glycosylation agents. The unique naphtho-α-pyrone structure of toralactone (5) was constructed by condensation of orsellinate 8 with pyrone 9 in the presence of LDA as developed by Staunton and co-workers. The naphthol of toralactone showed minimal reactivity as an acceptor and was screened with various glycosyl donors. It is finally concluded that sacrifice of an excess amount of the trifluoroacetimidate or trichloroacetimidate donors (6f/6g, 6.0 equiv) in the presence of a catalytic amount of TMSOTf (0.05 and 0.3 equiv, respectively) afforded excellent yields of the coupling product, which was otherwise only a minor product under a variety of conditions examined.
Sc(OTf)3-catalyzed acetolysis of 1,6-anhydro-β-hexopyranoses and solvent-free per-acetylation of hexoses
Lee, Jinq-Chyi,Tai, Cheng-An,Hung, Shang-Cheng
, p. 851 - 855 (2007/10/03)
Acetolysis of 1,6-anhydro-β-hexopyranoses and solvent-free per-acetylation of hexoses with acetic anhydride at room temperature in excellent yields employing 0.5 mol% scandium(III) trifluoromethanesulfonate as an extremely efficient catalyst are, respectively, described here.
On the regioselective acylation of 1,6-anhydro-β-D- and L-hexopyranoses catalysed by lipases: Structural bass and synthetic applications
Boissière-Junot, Nathalie,Tellier, Charles,Rabiller, Claude
, p. 99 - 115 (2007/10/03)
With the aim of providing new methods for the regioselective protection at the 2,3 and 4 positions of monosaccharides, we have studied the acetylation of a class of rigid sugars: the 1,6-anhydro-β-D- and L-hexopyranoses (hexopyranosanes D-1 to D-5 and L-1 to L-5), using vinyl acetate as an acyl donor and two common lipases,Candida rugosa and Pseudomonas cepacia, as catalysts. Our results indicate that the relative orientation of the hydroxyls governs the regioselectivity of acetylation. In the D-series, when the 3-OH is in the axial position, acetylation occurs mainly at the 4-axial OH, while the 2-axial OH is preferred when the 4-OH is equatorial. Conversely, when the 3-OH is equatorial, a strong selectivity affects the equatorial 2-OH. Compounds of the L-series were shown to be poor substrates for the lipase Pseudomonas cepacia except for L-galactosane for which the 2-monoacetyl ester was obtained in good yield. An attempt to rationalize the results by means of molecular modelling is also made to account for the catalytic activity of the Candida rugosa lipase on hexopyranosanes 1-3.
