- Controlling Sugar Deoxygenation Products from Biomass by Choice of Fluoroarylborane Catalyst
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The feedstocks from biomass are defined and limited by nature, but through the choice of catalyst, one may change the deoxygenation outcome. We report divergent but selective deoxygenation of sugars with triethylsilane (TESH) and two fluoroarylborane catalysts, B(C6F5)3 and B(3,5-CF3)2C6H3)3 (BAr3,5-CF3). To illustrate, persilylated 2-deoxyglucose shows exocyclic C-O bond cleavage/reduction with the less sterically congested BAr3,5-CF3, whereas endocyclic C-O bond cleavage/reduction predominates with the more Lewis acidic B(C6F5)3. Chiral furans and linear polyols can be selectively synthesized depending on the catalysts. Mechanistic studies demonstrate that the resting states of these catalysts are different.
- Seo, Youngran,Lowe, Jared M.,Gagné, Michel R.
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p. 6648 - 6652
(2019/08/26)
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- First protection-free protocol for synthesis of 1-deoxy sugars through glycosyl dithiocarbamate intermediates
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A practical two-step synthetic process for 1-deoxy sugars has been established. The process consists of the direct introduction of a dimethyldithiocarbamate group into the anomeric center of unprotected sugars and subsequent hydrogenation in the AIBN-H3PO2-NaHCO3 system. No protecting groups are needed to synthesize 1-deoxy monosaccharides and 1-deoxy disaccharides.
- Li, Gefei,Noguchi, Masato,Nakamura, Kensuke,Hayasaka, Ryohei,Tanaka, Yuuki,Shoda, Shin-ichiro
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supporting information
p. 3428 - 3431
(2018/08/20)
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- Total Synthesis of Neodysiherbaine A via 1,3-Dipolar Cycloaddition of a Chiral Nitrone Template
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The total synthesis of neodysiherbaine A was achieved via 1,3-dipolar cycloaddition of a chiral nitrone template with a sugar-derived allyl alcohol in the presence of MgBr2·OEt2. This cycloaddition constructed the C2 and C4 asymmetric centers in a single step. Then reductive cleavage, intramolecular SN2 reaction of the tertiary alcohol, and oxidation of the primary alcohol afforded neodysiherbaine A.
- Hirai, Toshihiro,Shibata, Kohki,Niwano, Yohei,Shiozaki, Masao,Hashimoto, Yoshimitsu,Morita, Nobuyoshi,Ban, Shintaro,Tamura, Osamu
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supporting information
p. 6320 - 6323
(2017/12/08)
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- An efficient method for the preparation of 1,5-anhydroalditol from unprotected carbohydrates via glycopyranosyl iodide
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A practical, facile method was developed for the preparation of 1,5-anhydroalditol via per-O-TMS-glycopyranosyl iodide with LiBH4. A series of 1,5-anhydroalditols were prepared in excellent yields (up to 92%) from unprotected carbohydrates within 2 days under mild conditions. In addition, multi-gram scale preparation of 1,5-anhydroglucitol (1,5-AG), a major polyol present in human serum, was developed using the same procedure without the need for chromatographic purification.
- Uchiyama, Taketo,Shishikura, Keisuke,Ogawa, Koji,Ohshima, Yuuki,Miyairi, Shinichi
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p. 5294 - 5296
(2016/11/11)
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- A biophysical study with carbohydrate derivatives explains the molecular basis of monosaccharide selectivity of the Pseudomonas aeruginosa lectin lecB
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The rise of resistances against antibiotics in bacteria is a major threat for public health and demands the development of novel antibacterial therapies. Infections with Pseudomonas aeruginosa are a severe problem for hospitalized patients and for patients suffering from cystic fibrosis. These bacteria can form biofilms and thereby increase their resistance towards antibiotics. The bacterial lectin LecB was shown to be necessary for biofilm formation and the inhibition with its carbohydrate ligands resulted in reduced amounts of biofilm. The natural ligands for LecB are glycosides of D-mannose and L-fucose, the latter displaying an unusual strong affinity. Interestingly, although mannosides are much weaker ligands for LecB, they do form an additional hydrogen bond with the protein in the crystal structure. To analyze the individual contributions of the methyl group in fucosides and the hydroxymethyl group in mannosides to the binding, we designed and synthesized derivatives of these saccharides.We report glycomimetic inhibitors that dissect the individual interactions of their saccharide precursors with LecB and give insight into the biophysics of binding by LecB. Furthermore, theoretical calculations supported by experimental thermodynamic data suggest a perturbed hydrogen bonding network for mannose derivatives as molecular basis for the selectivity of LecB for fucosides. Knowledge gained on the mode of interaction of LecB with its ligands at ambient conditions will be useful for future drug design.
- Sommer, Roman,Exner, Thomas E.,Titz, Alexer
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- Intramolecular dehydration of mannitol in high-temperature liquid water without acid catalysts
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Intramolecular dehydration of mannitol in high-temperature liquid water without adding any hazardous acid catalysts and its kinetic analyses were carried out. The dehydration behavior of mannitol was compared with that of sorbitol. 2,5-Anhydromannitol and 1,4-anhydromannitol were major products from the mannitol monomolecular dehydration in contrast with the only major product, 1,4-anhydrosorbitol, from the sorbitol monomolecular dehydration.
- Yamaguchi, Aritomo,Sato, Osamu,Mimura, Naoki,Shirai, Masayuki
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p. 45575 - 45578
(2014/12/12)
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- Preparation of anhydroalditols from commodity carbohydrates
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A practical process for the preparation of anhydroalditols from commodity carbohydrates has been described. Reductive cleavage of the glycosidic linkage in perallylated carbohydrates with triethylsilane gave the protected anhydroalditols, which were then deallylated using a PdCl2-CuCl2-Activated Charcoal system. Valuable anhydroalditols, such as 1,5-anhydro-D-glucitol, 1,5-anhydro-D-mannitol, 2,5-anhydro-D-glucitol, 2,5-anhydro-D-mannitol and 1,4-anhydro-Dribitol, were prepared in high yields and purity from carbohydrates, such as glucose, mannose, ribose, sucrose, cellulose, starch and levan.
- Yuan, Changyou,Hollingsworth, Rawle I.
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- Synthesis of octahydropyrano[3,2-b]pyrrole-2-carboxylic acid derivatives from d-mannose
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Bicyclic amino acids are useful building blocks in synthesizing biologically active molecules and peptidomimetics. 2-Carboxy-6-hydroxyloctahydroindole (Choi) is a novel bicyclic amino acid found in the marine natural products aeruginosins. Many compounds in the aeruginosin family exhibit inhibition activities toward serine proteases including thrombin and trypsin. The unique Choi structure is the common feature of this family of oligopeptides and this motif is important for their observed biological activities. To better understand the influence of the stereochemistry of the Choi core structure on the inhibition activities, we have previously synthesized ring-oxygenated variants from glucose. The preparation of octahydro-pyrano[3,2-b]pyrrole 2-carboxylic acids from d-mannose is reported here. These novel bicyclic amino acids can be used in the preparation of aeruginosin analogs, as well as conformationally constrained peptidomimetics or other biologically active molecules.
- Ella-Menye, Jean-Rene,Nie, Xiaoping,Wang, Guijun
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p. 1743 - 1753
(2008/12/21)
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- Stereoselective entry to β-linked C-disaccharides using a carbon-ferrier reaction
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(Matrix presented) The synthesis of unsaturated β-linked C-disaccharides by the Lewis acid-mediated reaction of 3-O-acetylated glycals with monosaccharide-derived alkenes is described. Deprotection and selective hydrogenation of an exocyclic carbon-carbon
- Gemmell, Natasha,Meo, Paul,Osborn, Helen M. I.
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p. 1649 - 1652
(2007/10/03)
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- Directed dihydroxylation of cyclic allylic alcohols and trichloroacetamides using OsO4/TMEDA
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The oxidation of a range of cyclic allylic alcohols and amides with OsO4/TMEDA is presented. Under these conditions, hydrogen bonding control leads to the (contrasteric) formation of the syn isomer in almost every example that was examined. Evidence for the bidentate binding of TMEDA to OsO4 is presented and a plausible mechanism described.
- Donohoe, Timothy J.,Blades, Kevin,Moore, Peter R.,Waring, Michael J.,Winter, Jon J. G.,Helliwell, Madeleine,Newcombe, Nicholas J.,Stemp, Geoffrey
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p. 7946 - 7956
(2007/10/03)
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- 1,5-Anhydro-D-fructose: Stereoselective conversions to 1,5- anhydroalditols and deoxy/amino substituted analogues
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1,5-Anhydro-D-fructose (1) has been converted into crystalline oximes. 1,5-Anhydroalditols and 2-amino-2-deoxy-1,5-anhydroalditols have been prepared by stereoselective reduction procedures from 1 and from the oximes, respectively.
- Andersen, Soren M.,Lundt, Inge,Marcussen, Jan
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p. 717 - 725
(2007/10/03)
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- A novel and efficient method for the oxidative removal of O-benzyl protective groups of carbohydrates by tetrabutylammonium peroxydisulfate
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Various benzyl ethers of carbohydrates have been selectively oxidized to the corresponding benzoate esters 2a-j with tetrabutylammonium peroxydisulfate under neutral conditions followed by debenzoylation with sodium methoxide to afford the debenzylated carbohydrates 3a-j in good overall yields. Noteworthy is that highly chemoselective reactions were achieved with the co-existence of other functionalities. Thieme Stuttgart.
- Chen, Fen-Er,Peng, Zuo-Zhong,Fu, Han,Meng, Ge,Cheng, Yu,Lü, Yin-Xiang
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p. 627 - 628
(2007/10/03)
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- The directed dihydroxylation of allylic alcohols
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The preparation and dihydroxylation of a series of polyenes and cyclic allylic alcohols using the TMEDA/osmium tetroxide mixture is reported. Remarkably, these reagents lead to high levels of regiochemical and stereochemical control as the oxidant hydroge
- Donohoe, Timothy J.,Moore, Peter R.,Waring, Michael J.,Newcombe, Nicholas J.
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p. 5027 - 5030
(2007/10/03)
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- Reductive cleavage of permethylated polysaccharides with borane-methyl sulfide complex and butyltin trichloride
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Several per-O-methylated monosaccharides and polysaccharides were used as models in an attempt to identify more convenient reagents for accomplishing reductive cleavage of glycosidic linkages. Included in the model studies were methyl α- and β-D-glucopyranoside, methyl α- and β-D-mannopyranoside, and methyl α- and β-D-ribofuranoside. These studies led to the identification of a new promoter, butyltin trichloride, for carrying out reductive cleavage when borane-methyl sulfide complex was used as the reducing agent. These reagents were found to accomplish the reductive cleavage of per-O-methylated amylose, cellulose, and pullulan to give only the expected derivatives of 1,5-anhydro-D-glucitol. These reagents also accomplished reductive cleavage of per-O-methylated inulin to give only the expected derivatives of 2,5-anhydro-D-mannitol and 2,5-anhydro-D-glucitol. Reductive cleavage using these reagents is easy to perform, and subsequent acetylation of the products is readily accomplished in situ.
- Wang, Nan,Gray, Gary R.
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p. 131 - 137
(2007/10/03)
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- A new strategy for the stereoselective syntheses of C-glycosyl compounds of β-pentapyranoses
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The C-glycosyl compounds of β-L-xylopyranose and β-D-arabinopyranose were conveniently prepared by reduction of methyl α-D-glucopyranoside and methyl α-D-mannopyranoside with triethylsilane in the presence of trimethylsilyl trifluoromethanesulfonate, respectively.
- Guo, Zhong-Wu,Hui, Yong-Zheng
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p. 2067 - 2073
(2007/10/03)
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- Enantiomerically Pure, Highly Functionalized Tetrahydrofurans from Simple Carbohydrate Precursors
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6-Bromo-6-deoxy-1,4-aldonolactones and 6-bromo-6-deoxy-alditols with D-galacto, D-altro-, D-manno- and D-ido-configuration were selectively converted into hydroxylated tetrahydrofuran derivatives by simple heating in water.The 6-bromo-6-deoxy-altritol (10) and 6-bromo-6-deoxy-D-iditol (25) reacted even at room temperature.Likewise, 6-bromo-2,6-dideoxy-aldonolactones with D-arabino- (29) and D-lyxo-configuration (31) gave the corresponding 2-deoxy-3,6-anhydride, when heated in water.The rate of formation of the furan ring by intramolecular nucleophilic substitution was determined by the conformation of the bromopolyols in water.
- Lundt, Inge,Frank, Holger
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p. 13285 - 13298
(2007/10/02)
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- A simple conversion of polyols into anhydroalditols
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A simple procedure, which consists of direct heating of pyridinium chloride and the starting material, is described for the dehydration of alditols. Anhydroalditols, of great interest for various applications, are thus obtained, and the selectivity of the reaction is discussed. Some selective protections for further uses of these products are studied.
- Duclos,Fayet,Gelas
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p. 1087 - 1090
(2007/10/02)
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- An Efficient Synthesis of Anhydroalditols and Allyl C-Glycosides
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Efforts to expedite production of anhydroalditols have led to a new, efficient synthesis of these compounds from alkyl glycosides.Silylation of the glycoside followed by reductive cleavage in the presence of triethylsilane and trimethylsilyl trifluoromethanesulfonate were carried out in the same reaction flask.Subsequent aqueous workup gave excellent yields of anhydroalditol(s).In some cases ring contraction was observed, but the use of bulkier silyl protecting groups gave greater yields of the expected product.This method was also shown to be an efficient means to prepare allyl C-glycosides, without any independent protecting or activating step, by simply replacing triethylsilane with allyltrimethylsilane in the synthetic scheme.
- Bennek, John A.,Gray, Gary R.
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p. 892 - 897
(2007/10/02)
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- Acid Catalyzed Dehydration of Alditols. Part I. D-Glucitol and D-Mannitol
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The acid catalyzed dehydration of D-glucitol and D-mannitol has been studied using 13C NMR spectroscopy to monitor the reactions.The products formed were identified and rate constants were measured.Dehydration of (1S)-1-2H-D-mannitol with 3 M sulfuric acid was shown to yield (1R)-1-2H-1,4:3,6-dianhydro-D-mannitol, showing that dehydration of D-mannitol to 1,4-anhydro-D-mannitol and, subsequently, to the 1,4:3,6-dianhydride takes place with inversion at the primary carbon atom.
- Bock, Klaus,Pedersen, Christian,Thoegersen, Henning
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p. 441 - 450
(2007/10/02)
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- A CONVENIENT ACCESS TO 1,5-ANHYDROKETOSES
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A convenient, verstile entry into the 1,5-anhydroketose series is described and their conversion into enolones, enolone oximes and γ-pyrones.
- Lichtenthaler, F. W.,Ashry E. S. H. El,Goeckel, V. H.
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p. 1429 - 1432
(2007/10/02)
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