- Selective synthesis of 1,6-anhydro-β-D-mannopyranose and -mannofuranose using microwave-assisted heating
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The dehydration of D-mannose and the demethanolization of methyl-α-D-mannopyranoside (MαMP) or methyl-α-D- mannofuranoside (MαMF) were examined using microwave-assisted heating for a 3-min irradiation at temperature from 120 to 280 °C in ordinary or dry sulfolane without any catalyst. The microwave-assisted heating of MαMP and MαMF smoothly proceeded to selectively afford the anhydromannoses, 1,6-anhydro-β-D-mannopyranose (AMP) and 1,6-anhydro-β-D-mannofuranose (AMF), respectively, in high yields. For MαMP in ordinary sulfolane at 240 °C, AMP was selectively obtained in the AMF:AMP ratio of 4:96, whereas AMF was the major product at the AMF:AMP ratio of 97:3 from MαMF in dry sulfolane at 220 °C.
- Hoai, Nguyen To,Sasaki, Akiyoshi,Sasaki, Masahide,Kaga, Harumi,Kakuchi, Toyoji,Satoh, Toshifumi
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- Regioselective acylation of 1,6-anhydro-β-D-manno and galactopyranose catalysed by lipases
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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.
- Junot, N.,Meslin, J.C.,Rabiller, C.
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- A Unified Strategy to Access 2- And 4-Deoxygenated Sugars Enabled by Manganese-Promoted 1,2-Radical Migration
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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.
- Carder, Hayden M.,Suh, Carolyn E.,Wendlandt, Alison E.
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supporting information
p. 13798 - 13805
(2021/09/07)
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- Catalytic Highly Regioselective C-H Oxygenation Using Water as the Oxygen Source: Preparation of 17O/18O-Isotope-Labeled Compounds
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We found that the oxygen atom of water is activated to iodosylbenzene derivatives via reversible hydrolysis of PhI(OOCR)2 and can be used to the oxygen source for ruthenium(bpga)-catalyzed site-selective C-H oxygenation. Ru(bpga)/PhI(OOCR)2/H2O system, sterically less bulky methinic and methylenic C-H bonds in various compounds can be converted to desired oxygen functional groups in a site-selective manner. Using this method, oxygen-isotope labeled compounds such as d-[3-17O/18O]-mannose can be prepared in a multigram scale.
- Doiuchi, Daiki,Uchida, Tatsuya
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supporting information
p. 7301 - 7305
(2021/10/01)
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- Synthesis of unstable 4-benzoyl-1,6-anhydro-3-keto-β-D-mannopyranose via stereoselective photobromination of 2,3-isopropylidene-4-benzoyl-1,6-anhydro-β-D-mannopyranose
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Stereoselective photobromination of 1,6-anhydro-β-D-glucopyranose derivatives occurs at exo-H6. However, photobromination of 4-benzoyl-2,3-isopropylidene-1,6-anhydro-β-D-mannopyranose 6 produced unstable 4-benzoyl-1,6-anhydro-3-keto-β-D-mannopyranose 7. The mechanism of stereoselective oxidation at C-3 could be attributed to the facile radical proton abstraction at C-3, followed by the subsequent bromination of the isopropylidene group, which was subsequently eliminated during the aqueous workup. Thus, the aim of this article is to identify the molecular structure of the unstable compound 7.
- Mahdi, Jassem G.,Dawoud, Hanaa M.,Manning, Abigail J.,Lieberman, Harvey F.,Kelly, David R.
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- Oligosaccharide compound and its manufacture and its intermediate
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The purpose of the present invention is to provide an oligosaccharide with high versatility that can produce a protected sulfate oligosaccharide that can become a manufacturing intermediate of polysulfated hyaluronic acid, and to provide a manufacturing method therefor and an intermediate thereof. Position 2 amino groups in glucosamine, galactosamine, and the like can react with saccharide receptors having an electron attracting group such as glucuronic acid and protected sulfate groups, by using a saccharide donor protected by a specific protective group.
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Paragraph 0242; 0243; 0244
(2018/04/14)
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- From D-Glucose to Biologically Potent L-Hexose Derivatives: Synthesis of α-L-Iduronidase Fluorogenic Detector and the Disaccharide Moieties of Bleomycin A2 and Heparan Sulfate
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A novel and convenient route for the synthesis of biologically potent and rare L-hexose derivatives from D-glucose is described. Conversion of diacetone-α-D-glucose (14) into 1,2:3,5-di-O-isopropylidene-β -L-idofuranose (19) was efficiently carried out in two steps. Orthogonal isopropylidene rearrangement of compound 19 led to 1,2:5,6-di-O-isopropylidene-β-L-idofuranose (27), which underwent regioselective epimerization at the C3 position to give the L-talo- and 3-functionalized L-idofuranosyl derivatives. Hydrolysis of compound 19 under acidic conditions furnished 1,6-anhydro-β-L-idopyranose (35) in excellent yield, which was successfully transformed into the corresponding L-allo, L-altro, L-gulo, and L-ido derivatives via regioselective benzylation, benzoylation, triflation and nucleophilic substitution as the key steps. Applications of these 1,6-anhydro-β-L-hexopyranoses as valuable building blocks to the syntheses of 4-methylcoumarin-7-yl-α-L-iduronic acid and the disaccharide moieties of bleomycin A2 as well as heparan sulfate are highlighted.
- Lee, Jinq-Chyi,Chang, Shu-Wen,Liao, Chih-Cheng,Chi, Fa-Chen,Chen, Chien-Sheng,Wen, Yuh-Sheng,Wang, Cheng-Chung,Kulkarni, Suvarn S.,Puranik, Ramachandra,Liu, Yi-Hung,Hung, Shang-Cheng
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p. 399 - 415
(2007/10/03)
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- A carbohydrate synthesis employing a photochemical decarbonylation
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A new route to the aldopentoses, ribose and lyxose, and the aldohexoses, talose and gulose, has been developed using chiral building blocks containing a bicyclo[3.2.1]octane framework by employing a photochemical decarbonylation reaction as the key step.
- Kadota, Kohei,Ogasawara, Kunio
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p. 8661 - 8664
(2007/10/03)
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- 5-exo Radical Cyclization onto 3-Alkoxyketimino-1,6-anhydromannopyranoses. Efficient Preparation of Synthetic Intermediates for (-)-Tetrodotoxin
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Ketoxime ethers at C3 of 1,6-anhydro-β-D-mannopyranose derivatives were found to be useful 5-exo radical traps of alkyl and vinyl radicals generated at a chain tethered to the C2 hydroxyl group, allowing advanced synthetic intermediates for (-)-tetrodotoxin to be prepared from D-mannose in good overall yield.
- Noya,Paredes,Ozores,Alonso
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p. 5960 - 5968
(2007/10/03)
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- On the regioselective acylation of 1,6-anhydro-β-D- and L-hexopyranoses catalysed by lipases: Structural bass and synthetic applications
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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.
- Boissière-Junot, Nathalie,Tellier, Charles,Rabiller, Claude
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- Studies related to synthesis of glycophosphatidylinositol membrane-bound protein anchors. 6. Convergent assembly of subunits
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Glycophosphatidylinositol anchors of membrane-bound proteins are thought to comprise a common pentasaccharide core containing mannan, glucosamine, and inositol residues. A synthetic route to this core is described. In addition, the complete heptasaccharide moiety of the rat brain Thy-1 membrane anchor, the first mammalian membrane anchor to be characterized, has been synthesized. In the case of the Thy-1 anchor, the synthetic plan is based on three building blocks comprising glucosamine-inositol, galactosamine-mannose, and trimannan residues. Although glycosyl donors other than n-pentenyl glycosides (NPGs) have been used in preparing each of these building blocks, the final assembly of the heptasaccharide utilizes NPGs as the only glycosyl donors. The mildness of the conditions for these coupling reactions has allowed us to make provisions for subsequent installation of the three phosphodiester units.
- Madsen, Robert,Udodong, Uko E.,Roberts, Carmichad,Mootoo, David R.,Konradsson, Peter,Fraser-Reid, Bert
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p. 1554 - 1565
(2007/10/02)
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- 2,3,4-Tri-O-acetyl-1,6-anhydro-β-D-mannopyranose, an artifact produced during carbohydrate analysis. A total synthesis of 2,3,5-tri-O-acetyl-1,6-anhydro-β-D-mannofuranose
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This study confirms that 2,3,4-tri-O-acetyl-1,6-anhydro-β-D-mannopyranose is an artifact produced during carbohydrate analysis. A new synthesis of 2,3,5-tri-O-acetyl-1,6-anhydro-β-D-mannofuranose is also described, and a novel dimer, 1,6':6,1'-dianhydro-2,3:2',3'-di-O-isopropylidene-5,5'-di-O-(1-methoxy ethyl)-di-α-D-mannofuranose, has been isolated. The structure of the dimer is confirmed by X-ray analysis of a derivative, 1,6':6,1'-dianhydro-2,3:2',3'-di-O-isopropylidene-di-α-D-mannofuranos e. This study confirms that 2,3,4-tri-O-acetyl-1,6-anhydro-β-D-mannopyranose is an artifact produced during carbohydrate analysis. A new synthesis of 2,3,5-tri-O-acetyl-1,6-anhydro-β-D-mannofuranose is also described, and a novel dimer, 1,6′:6,1′- dianhydro-2,3:2′,3′-di-O- isopropylidene-5,5′-di-O-(1-methoxyethyl)-di-α-D- mannofuranose, has been isolated. The structural of the dimer is confirmed by X-ray analysis of a derivative, 1,6′:6, 1′-dianhydro-2,3:2′,3′-di-O-isopropylidene- di-α-D-mannofuranose.
- Manna,McAnalley,Ammon
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- Cycloheptaamylose as a model for starch in the pyrolysis of polysaccharides
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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.
- Lowary,Richards
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p. 157 - 166
(2007/10/02)
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- A Mild Procedure for the Preparation of 1,6-Anhydro-β-D-hexopyranoses and Derivatives
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Treatment of reducing 6-O-tosyl-D-glucopyranoses 1 with 1,8-diazabicycloundec-7-ene (DBU) afforded the corresponding 1,6-anhydro-β-D-hexopyranoses 2 in high yields.Reaction was also performed on partly acetylated tosylates of carbohydrates.
- Lafont, Dominique,Boullanger, Paul,Cadas, Olivier,Descotes, Gerard
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p. 191 - 194
(2007/10/02)
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- O-BENZYL PROTECTING GROUPS AS HYDROGEN DONORS IN CATALYTIC TRANSFER HYDROGENOLYSIS. SELECTIVE DEBENZYLATION OF 1,6-ANHYDRO HEXOSES.
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O-benzyl protecting groups may act as hydrogen donors in heterogenous catalytic transfer hydrogenolysis.Hydrogenolysis of compunds 1 - 4 demonstrated that this hydrogen transfer occurs adjacent cis-disposed hydroxyl groups are present.
- Cruzado, Carmen M. del,Martin-Lomas, Manuel
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p. 2497 - 2500
(2007/10/02)
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- THE RELATIVE STABILITY OF ALLYL ETHER, ALLYLOXYCARBONYL ESTER AND PROP-2 ENYLIDENE ACETAL, PROTECTIVE GROUPS TOWARD IRIDIUM, RHODIUM AND PALLADIUM CATALYSTS.
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The deprotection of allyloxycarbonyl derivatives of sugars was realized in the presence of allylether or prop-2-enylidene acetal with Pd(PPh3)4 or RhCl(PPh3)3 as catalyst while PF6 isomerized selectively the allyl ethers.
- Kloosterman, M,Boom, J. H. Van,Chatelard, P.,Boullanger. P.,Descotes, G.
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p. 5045 - 5048
(2007/10/02)
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- One-Step Stereoselective Syntheses of C-Branched α-Deoxycyclitols from 1,6-Anhydrohexopyranoses
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1,6-Anhydro-3,4-O-isopropylidene-β-D-galactopyranose (1) reacts with n-butyllithium to give exclusively 1D-1-C-butyl-2,3-O-isopropylidene-1,2,3,5/4-cyclohexanepentol (2a). 1,6-Anhydro-2,3-O-isopropylidene-β-D-mannopyranose (7) gives 1L-5-C-butyl-2,3-O-isopropylidene-1,2,3/4,5-cyclohexanepentol (8a) and 1L-1-C-butyl-3,4-O-isopropylidene-1,2,5/3,4-cyclohexanepentol (9a) as a by-product.Analogous reactions with methyllithium yield the corresponding C-methyl-branched deoxyinositols 2b, 4, 8b, and 9b.
- Klemer, Almuth,Kohla, Monika
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p. 1662 - 1671
(2007/10/02)
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- OUVERTURE PAR LE N-BROMOSUCCINIMIDE DES ACETALS BENZYLIDENIQUES DE METHYL-HEXOSIDES DE CONFIGURATION MANNO ET SYNTHESE DE LA N-ACETYL-L-MYCOSAMINE
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Methyl 2,3:5,6-di-O-benzylidene-α-D-mannofuranoside and methyl 2,3-O-benzylidene-α-L-rhamnofuranoside were prepared according to a new procedure by simultaneous glycosidation and acetalation of D-mannose and L-rhamnose.Treatment of these compounds and of 1,6-anhydro-2,3-O-benzylidene-D-mannose with N-bromosuccinimide gave exclusively the 3-bromo compounds by regiospecific opening of the acetal ring.Thus, starting from rhamnose, N-acetyl-L-mycosamine (3-amino-3,6-dideoxy-L-mannose) was prepared in seven steps with a 32percent overall yield.
- Florent, Jean-Claude,Monneret, Claude
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p. 243 - 258
(2007/10/02)
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