644-76-8Relevant academic research and scientific papers
A Unified Strategy to Access 2- And 4-Deoxygenated Sugars Enabled by Manganese-Promoted 1,2-Radical Migration
Carder, Hayden M.,Suh, Carolyn E.,Wendlandt, Alison E.
supporting information, p. 13798 - 13805 (2021/09/07)
The selective manipulation of carbohydrate scaffolds is challenging due to the presence of multiple, nearly chemically indistinguishable O-H and C-H bonds. As a result, protecting-group-based synthetic strategies are typically necessary for carbohydrate modification. Here we report a concise semisynthetic strategy to access diverse 2- and 4-deoxygenated carbohydrates without relying on the exhaustive use of protecting groups to achieve site-selective reaction outcomes. Our approach leverages a Mn2+-promoted redox isomerization step, which proceeds via sugar radical intermediates accessed by neutral hydrogen atom abstraction under visible light-mediated photoredox conditions. The resulting deoxyketopyranosides feature chemically distinguishable functional groups and are readily transformed into diverse carbohydrate structures. To showcase the versatility of this method, we report expedient syntheses of the rare sugars l-ristosamine, l-olivose, l-mycarose, and l-digitoxose from commercial l-rhamnose. The findings presented here validate the potential for radical intermediates to facilitate the selective transformation of carbohydrates and showcase the step and efficiency advantages attendant to synthetic strategies that minimize a reliance upon protecting groups.
High-pressure fast-pyrolysis, fast-hydropyrolysis and catalytic hydrodeoxygenation of cellulose: Production of liquid fuel from biomass
Venkatakrishnan, Vinod Kumar,Degenstein, John C.,Smeltz, Andrew D.,Delgass, W. Nicholas,Agrawal, Rakesh,Ribeiro, Fabio H.
, p. 792 - 802 (2014/02/14)
A lab-scale, high-pressure, continuous-flow fast-hydropyrolysis and vapor-phase catalytic hydrodeoxygenation (HDO) reactor has been successfully designed, built and tested with cellulose as a model biomass feedstock. We investigated the effects of pyrolysis temperature on high-pressure cellulose fast-pyrolysis, hydrogen on high-pressure cellulose fast-hydropyrolysis, reaction pressure (27 bar and 54 bar) on our reactor performance and candidate catalysts for downstream catalytic HDO of cellulose fast-hydropyrolysis vapors. In this work, a liquid chromatography-mass spectrometry (LC-MS) method has been developed and utilized for quantitative characterization of the liquid products. The major compounds in the liquid from cellulose fast-pyrolysis (27 bar, 520 °C) are levoglucosan and its isomers, formic acid, glycolaldehyde, and water, constituting 51 wt%, 11 wt%, 8 wt% and 24 wt% of liquid respectively. Our results show that high pressures of hydrogen do not have a significant effect on the fast-hydropyrolysis of cellulose at 480 °C but suppress the formation of reactive light oxygenate species like glycolaldehyde and formic acid at 580 °C. The formation of permanent gases (CO, CO2, CH4) and glycolaldehyde and formic acid increased with increasing pyrolysis temperature in the range of 480 °C-580 °C in high-pressure cellulose fast-pyrolysis, in the absence of hydrogen. Candidate HDO catalysts Al 2O3, 2% Ru/Al2O3 and 2% Pt/Al 2O3 resulted in extents of deoxygenation of 20%, 22% and 27%, respectively, but led to carbon loss to gas phase as CO and CH4. These catalysts provide useful insights for other candidate HDO catalysts for improving the extent of deoxygenation with higher carbon recovery in the liquid product.
Direct synthesis of 1,6-anhydro sugars from unprotected glycopyranoses by using 2-chloro-1,3-dimethylimidazolinium chloride
Tanaka, Tomonari,Huang, Wei Chun,Noguchi, Masato,Kobayashi, Atsushi,Shoda, Shin-ichiro
supporting information; experimental part, p. 2154 - 2157 (2009/08/17)
Various 1,6-anhydro sugars have been synthesized directly from the corresponding unprotected glycopyranoses in excellent yields by using 2-chloro-1,3-dimethylimidazolinium chloride (DMC) as a dehydrative condensing agent. The reactions took place smoothly under mild reaction conditions in aqueous media. The present method would be a practical tool for synthesis of 1,6-anhydro derivatives of monosaccharides, linear-oligosaccharides, and branched-oligosaccharides.
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.
Regioselective acylation of 1,6-anhydro-β-D-manno and galactopyranose catalysed by lipases
Junot, N.,Meslin, J.C.,Rabiller, C.
, p. 1387 - 1392 (2007/10/02)
Pseudomonas fluorescens lipase (Amano) was found to be highly regioselective in the transesterification of 1,6-anhydro-β-D-manno and galactopyranose (mannosane and galactosane respectively) using vinyl acetate as an acyl donor.As in the case of 1,6-anhydro-β-D-glucopyranose (glucosane, the 4-OH axial group of mannosane is preferred, while the titled lipase catalysed the regioselective transesterification at the 2-axial OH of galactosane.The enzymatic acylation affords monoesters of the 1,6-anhydropyranoses which are difficult to obtain using conventional methods.
1,6-CYCLIZATION REACTIONS OF SELECTED ALDOHEXOPYRANOSES via THEIR 1-O-TOSYL DERIVATIVES
Wisniewski, Andrzej,Madaj, Janusz,Skorupowa, Eugenia,Sokolowski, Janusz
, p. 873 - 880 (2007/10/02)
2,3,4,6-Tetra-O-acetyl-D-gluco-, D-galacto- and D-mannopyranoses were tosylated with p-tolenesulfonyl chloride to afford their 1-O-tosyl derivatives which were cyclized "in situ" in a methanolic solution of sodium methoxide. 1,6-Cyclization products were obtained only with D-glucose and D-galactose derivatives.Cyclization of derivatives of D-glucose i.e. 2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl chloride, 3,4,6-tri-O-acetyl-1,2-anhydro-α-D-glucopyranose (Brigl's anhydride) and 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide enabled the 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) and their components were identified by coinjection with standards.
SYNTHESIS OF D-ALLOSAN FROM LEVOGLUCOSENONE
Matsumoto, Katsuya,Ebata, Takashi,Koseki, Koshi,Kawakami, Hiroshi,Matsushita, Hajime
, p. 2225 - 2240 (2007/10/02)
The stereoselective reduction and cis-dihydroxylation of levoglucosenone (1,6-anhydro-3,4-dideoxy-β-D-glycero-hex-3-enopyranos-2-ulose), gave D-allosan (1,6-anhydro-β-D-allopyranose) in high yield.
Cycloheptaamylose as a model for starch in the pyrolysis of polysaccharides
Lowary,Richards
, p. 157 - 166 (2007/10/02)
The pyrolysis of cycloheptaamylose has been studied as a model for starch. 1,6-Anhydro-β-D-glucopyranose (levoglucosan, LG, 7) and its furanose isomer are major products from vacuum pyrolysis at 280, 300, and 320°, with combined yields ranging from 38 to 50% of the substrate-dependent on temperature. Pyrolysis in methyl sulfoxide at 150° produced LG and glucose as well as gluco-oligosaccharides of d.p. up to 7, with both reducing and 1,6-anhydro end-groups. A mechanism is postulated in which the first step is the heterolytic scission of a glucosidic linkage to form a linear, seven-membered oligosaccharide having a glucosyl cation in place of the reducing end-group. The cation is stabilized either by intramolecular attack of O-6 on the C-1 cation or by intermolecular transglycosylation. The former product subsequently yields LG upon scission of a terminal glucosidic linkage. The pyrolysis of cycloheptaamylose has been studied as a model for starch. 1,6-Anhydro-β-D-glucopyranose (levoglucosan, LG, 7) and its furanose isomer are major products from vacuum pyrolysis at 280, 300, and 320°, with combined yields ranging from 38 to 50% of the substrate dependent on temperature. Pyrolysis in methyl sulfoxide at 150° produced LG and glucose as well as gluco-oligosaccharides of d.p. up to 7, with both reducing and 1,6-anhydro end-groups. A mechanism is postulated in which the first step is the heterolytic scission of a glucosidic linkage to form a linear, seven-membered oligosaccharide having a glucosyl cation in place of the reducing end-group. The cation is stabilized either by intramolecular attack of O-6 on the C-1 cation or by intermolecular transglycosylation. The former product subsequently yields LG upon scission of a terminal glucosidic linkage.
Synthesis of Levoglucosenone
Shibagaki, Makoto,Takahashi, Kyoko,Kuno, Hideyuki,Honda, Ichiro,Matsushita, Hajime
, p. 306 - 310 (2007/10/02)
Levoglucosenone was synthesized from D-galactose via reductive decarboxylation as a key reaction.Among the catalysts used for the key reaction, hydrous zirconium oxide was found to have the best activity.
