- Additive-controlled synthesis of 1- and 2-dexoysugars from thioglycosides
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Two photoreactions for the synthesis of 1- and 2-deoxysugars from thioglycosides were developed. In the presence of Hantzsch ester as an additive, a wide range of 1-deoxysugars were synthesized in moderate to excellent yields under irradiation with UV light without an exogenous photosensitizer. On the other hand, the utilization of 2,4,6-tri-tert-butylpyrimidine (TTBP) as the additive furnished a variety of 2-deoxysugars as the main products from their corresponding thioglycosides. The reported methodology has a broad substrate scope and high functional group tolerance and is scalable to gram-scale reaction.
- Wu, Xia,Wu, Biao,Gao, Chen-Fei,Ye, Xin-Shan,Xiong, De-Cai
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p. 479 - 500
(2021/12/29)
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- NaBH3CN and other systems as substitutes of tin and silicon hydrides in the light or heat-initiated reduction of halosugars: A tunable access to either 2-deoxy sugars or 1,5-anhydro-itols
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UV light-promoted reduction of acetobromoglucose by NaBH3CN in t-BuOH afforded 1,3,4,6-tetra-O-acetyl-2-deoxy-α-d-arabino-hexopyranose in high yield and purity, via a Surzur-Tanner rearrangement, while, with 10 mol % thiophenol added, acetylated 1,5-anhydro-d-glucitol was cleanly obtained. Such tin-free and mild reductions, presumed to proceed via radical pathways, were more efficient with NaBH3CN compared to NaBH4 or NaBD 4, and do not occur with acetochloroglucose. Similar reductions to 1,3,4,6-tetra-O-acetyl-2-deoxy-α-d-arabino-hexopyranose were achieved upon heating to 80 C t-BuOH or CH3CN solutions of NaBH3CN and AIBN, but with a lower selectivity due to competing ionic reactions. With other pyranosyl bromides, reductions by NaBH3CN could be tuned similarly (d-galacto), but some (d-manno, 5-thio-d-xylo) gave mainly or exclusively 1,5-anhydro-itols. Other conditions, or reagents promoting SET process, afforded also reduced products, but with lower rates or selectivities. Primary iodides were reduced readily with NaBH3CN under UV light.
- Bruyère, Isabelle,Tóth, Zoltan,Benyahia, Hamida,Xue, Jia Lu,Praly, Jean-Pierre
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supporting information
p. 9656 - 9662
(2013/10/22)
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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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- Towards α- or β-D-C-glycosyl compounds by tin-catalyzed addition of glycosyl radicals to acrylonitrile and vinylphosphonate, and flexible reduction of tetra-O-acetyl-α-D-glucopyranosyl bromide with cyanoborohydride
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Photo-induced radical addition of acetylated α-D-glucopyranosyl bromide (1) to acrylonitrile or diethyl vinylphosphonate, in the presence of catalytic amounts of tri-n-butyltin chloride and sodium (or tetra-n-butylammonium) cyanoborohydride in excess, all
- Praly, Jean-Pierre,Ardakani, Azin Salek,Bruyere, Isabelle,Marie-Luce, Chrystelle,Bing Qin, Bing
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p. 1623 - 1632
(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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- Nickel-catalysed synthesis of C-glycosides and deoxysugars from glycosyl bromides
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A radical-based synthesis of C-glycosides from glycosyl bromides is reported, in which the traditional tin hydride methods are replaced by the use of a nickel (II) salt and manganese dust. The reactions are operationally simpler and in many cases higher y
- Readman,Marsden,Hodgson
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p. 1628 - 1630
(2007/10/03)
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- Enantioselective radical-chain hydrosilylation of alkenes using homochiral thiols as polarity-reversal catalysts
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The thiol-catalysed radical-chain additions of triphenylsilane and of tris(trimethylsilyl)silane to a number of cyclic prochiral terminal alkenes have been carried out at 60°C in the presence of di-tert-butyl hyponitrite as initiator. The function of the thiol catalyst is to promote the overall abstraction of hydrogen from the silane by the nucleophilic carbon-centred radical intermediate, formed by addition of the silyl radical to the alkene, and the stereogenic centre in the final adduct is set by hydrogen-atom transfer from the thiol to this β-silylalkyl radical. When the thiol is homochiral the transfer of hydrogen becomes enantioselective and an optically active adduct results. A number of homochiral thiols were investigated and the highest enantiomeric excesses (up to 95%) were achieved using the tetra-O-acetyl derivatives of 1-thio-β-D-glucopyranose and 1-thio-β-D-mannopyranose. The absolute configuration of an enantiopure triphenylsilane adduct (upgraded by recrystallisation) was determined by X-ray crystallography and it was shown that this adduct could be oxidatively desilylated to the corresponding alcohol and acetate with no loss of enantiomeric purity.
- Haque, M. Bodrul,Roberts, Brian P.,Tocher, Derek A.
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p. 2881 - 2889
(2007/10/03)
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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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- A NEW SYNTHESIS OF 2,3,4,6-TETRA-O-BENZYL-D-GLUCOPYRANOSYLIDENE ACETALS, USING TRIMETHYLSILYL TRIFLUOROMETHANESULFONATE AS THE CATALYST
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The title compounds were synthesized by condensation of 2,3,4,6-tetra-O-benzyl-D-glucono-1,5-lactone with bis-O-(trimethylsilyl)-1,2-diols in the presence of trimethylsilyl trifluoromethanesulfonate as the catalyst.Application to cis- and trans-1,2-diols
- Horito, Shigeomi,Asano, Katsuji,Umemura, Kazuyuki,Hashimoto, Hironobu,Yoshimura, Juji
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p. 175 - 186
(2007/10/02)
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