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1.
Shivaji A. Thadke 《Tetrahedron letters》2010,51(45):5912-5914
Various 1,6-anhydro sugars are synthesized utilizing salient features of gold-catalyzed glycosidations. All the reactions occurred under mild conditions in the presence of 7 mol % of AuBr3 enabling easy synthesis of 1,6-anhydro sugars from corresponding 6-hydroxy propargyl/methyl monosaccharides, disaccharides, and trisaccharides in good yields. 相似文献
2.
Tomonari Tanaka 《Tetrahedron letters》2009,50(18):2154-10197
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. 相似文献
3.
4.
Stereoselective Synthesis of Glycosyl Cyanides by TMSOTf-Mediated Ring Opening of 1,6-Anhydro Sugars
Dr. Yan Liang Adrien G. Laporte Dr. Anne Bodlenner Philippe Compain 《European journal of organic chemistry》2023,26(5):e202201311
We describe herein a convenient access to glycosyl cyanides by way of TMSCN ring opening of 1,6-anhydro sugars mediated by TMSOTf with modest to high stereocontrol in the D-gluco, D-galacto and D-manno series. The reaction is tolerant to various functional groups including free alcohols, alkenes and terminal alkynes. The straightforward synthesis of a constrained analogue of 1-cyano-D-glucal with a 3,6-anhydro sugar framework is presented to illustrate the interest of the TMSCN ring-opening reaction. 相似文献
5.
Treatment of D-glucose-derived alkene 4 with cyclopentadiene in the presence of a Lewis acid results in the formation of cycloaddition products 8-11. Evidence is presented to show that these 1,6-anhydro sugar-cyclopentadiene adducts do not arise from rearrangement of 4 to isolevoglucosenone (5) followed by cycloaddition but are the result of Lewis acid-catalyzed rearrangement of alkene 4 to acyclic dienophile 12 followed by addition of cyclopentadiene. Major cycloadduct 8 has been utilized as a source of the enantiomerically pure carbocycles 14-25 by manipulation of the alkene and ketone functions and cleavage of the 1,6-anhydro bridge. In the absence of diene, alkene 4 undergoes rearrangement to enone 5 in 32% yield. Reaction of 5 with several dienes results only in the formation of "bottom-face" adducts 10,11, 28, and 29, and conjugate addition of either HN(3) or Me(3)COOH is found to be completely stereoselective to afford 30 and 31, respectively. Subsequent manipulation of azide 30 leads to precursors of several naturally occurring 2-amino-2,3-dideoxy sugars. 相似文献
6.
吡喃糖的1,2-及1,3-缩水内醚苄醚由相应的吡喃糖的C-2氧负离子(对1,3-缩水内醚是C-3氧负离子)与连有氯原子的C-1经分子内关环反应而制备, 而有些吡喃糖的1,2-缩水内醚苄醚是由相应的吡喃糖的C-1氧负离子与连有对甲苯磺酰氧基的C-2经分子内关环(倒关环)反应而得。呋喃糖的1,2-缩水内醚苄醚只能用倒关环法合成。1,2-(或1,3-)缩水内醚糖的开环反应通常给出1,2-反式连接(对1,3缩水内醚是1,3反式连接)的糖苷键。1,2-及1,3-缩水内醚糖的构象分析是通过^1H NMR测定及分子力学计算的方法而完成的。 相似文献
7.
《Mendeleev Communications》2022,32(1):100-102
Reactions of acetaldehyde with Diels–Alder adducts of levoglucosenone with butadiene, isoprene, and cyclohexa-diene assisted by low-valence titanium afford products of acetaldehyde addition to the acetal center with opening of the 1,6-anhydro bridge. In the case of the cyclopentadiene adduct, the reaction gives the product of addition of the ethyl substituent to the acetal center while the 1,6-anhydro bridge remains unchanged. 相似文献
8.
Azidation of 1,2-anhydro sugars with NaN(3) in CH(3)CN by using a catalytic amount of ceric ammonium nitrate has been accomplished in a regio- and stereoselective manner. Various 1,2-anhydro sugars produced 2-hydroxy-1-azido sugars in good yields which, in turn, were converted to structurally diverse sugar-derived morpholine triazoles and sugar oxazin-2-ones. These sugar derivatives were tested against various commercially available glycosidases, and two of them were found to be active in the micromolar range. 相似文献
9.
Pedro O MirandaIgnacio Brouard Juan I PadrónJaime Bermejo 《Tetrahedron letters》2003,44(20):3931-3934
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. 相似文献
10.
D'Alonzo D Guaragna A Napolitano C Palumbo G 《The Journal of organic chemistry》2008,73(14):5636-5639
An expeditious and efficient synthesis of 1,6-anhydro-beta-L-hexopyranosyl derivatives 3 as valuable building blocks for the preparation of L-sugars is herein reported. This route relies upon the use of a domino reaction involving five synthetic steps from the 5,6-dihydro-1,4-dithiin 4. As 1,6-anhydro derivatives 3 are obtained, dithioethylene bridge removal and double-bond dihydroxylation give access to protected L-allose and L-glucose in stereoselective fashion and high yields. 相似文献
11.
Faizullina L. Kh. Galimova Yu. S. Khalilova Yu. A. Valeev F. A. 《Russian Journal of Organic Chemistry》2021,57(7):1047-1052
Russian Journal of Organic Chemistry - Opening of the 1,6-anhydro bridge in levoglucosenone by the action of acetic anhydride in the presence of ZnCl2 afforded diastereoisomeric... 相似文献
12.
B. T. Sharipov O. Yu. Krasnoslobodtseva L. V. Spirikhin F. A. Valeev 《Russian Journal of Organic Chemistry》2010,46(1):129-137
Methods of opening of the 1,6-anhydro bridge in levoglucosenone (ZnCl2-Ac2O), its adducts with isoprene (ZnCl2-Ac2O, HCl-MeOH), and hydroxy derivatives (H3PO4-Ac2
O) were studied. Cleavage of the 1,6-anhydro bridge in anomeric acetoxy derivatives of levoglucosenone-isoprene adduct by the
action of BF3 · Et2O-Ac2O was accompanied by acetylation at the allylic C
6 position. 相似文献
13.
Abhijeet K. Kayastha 《Tetrahedron letters》2010,51(40):5269-6198
Armed/disarmed effect of propargyl glycosides in the presence of AuBr3 is studied. Observed that oxophilic AuBr3 cleaves interglycosidic bond of an armed disaccharide resulting in the formation of a disaccharide and a 1,6-anhydro sugar. Trisaccharides were obtained after fine tuning the reactivity of the glycosyl donor with different protecting groups. 相似文献
14.
[reaction: see text]. A novel approach to simple C-glycosides is reported. Reductive ring opening of 1,2-anhydro sugars with titanocene(III) chloride produces an anomeric radical that can be trapped with a variety of agents. The reaction stereospecifically affords alpha-glycosides and produces a free C-2 hydroxyl group allowing for further elaboration. 相似文献
15.
Karban J Císařová I Strašák T Šťastná LČ Sýkora J 《Organic & biomolecular chemistry》2012,10(2):394-403
A complete series of eight 1,6:2,3- and 1,6:3,4-dianhydro-β-D-hexopyranoses were subjected to fluorination with DAST. The 1,6:3,4-dianhydropyranoses yielded solely products of skeletal rearrangement resulting from migration of the tetrahydropyran oxygen (educts of D-altro and D-talo configuration) or of the 1,6-anhydro bridge oxygen (D-allo, D-galacto). The major products yielded by the 1,6:2,3-dianhydropyranoses were compounds arising from nucleophilic substitution, with configuration at C4 either retained (D-talo, D-gulo) or inverted (D-manno), or from C6 migration (D-allo). The minor products in the 1,6:2,3-series resulted from migration of the tetrahydropyran oxygen (D-gulo) or the oxirane oxygen (D-manno), or from nucleophilic substitution with retention of configuration (D-manno). The structure of most of the rearranged products was verified by X-ray crystallography. 相似文献
16.
[chemical reaction: see text]. A simple and efficient method for rearranging 2,3-anhydro carbohydrates to unsaturated sugars has been developed. The exceptionally mild reaction conditions and high stereoselectivity should make this an attractive method for the preparation of unsaturated carbohydrate derivatives. 相似文献
17.
ABSTRACT Thioacetolysis of per-O-benzylated and per-O-acetylated derivatives of 1,6-anhydro-β-D-glucopyranose (1 and 3) with acetyl sulfide using acidic catalysts gave α- and β-anomers of 1-S-acetyl-1-thio-D- glucopyranose, respectively. The formation of the β-anomer from 3 was in contrast to the predominance of the α-anomer as the product of the usual acetolysis of 3. Similar thioacetolysis of per-O-benzylated 1,6-anhydro-maltose (5) under optimized conditions resulted in opening of the 1,6-anhydro ring and simultaneous removal of the C-6′ benzyl group without cleavage of the internal glycosidic linkage, giving the 6,6′-di-O-acetyl-1-S-acetyl-α-thio-maltose derivative (6) in moderate yield. 相似文献
18.
SynthesesofCelulose┐TypePolysaccharidebyMeansofRing┐OpeningCopolymerizationofAnhydroribosesABRPandAIRPWUCheng-peiandPANCai-yu... 相似文献
19.
The CD of saturated iridoids containing a 2.9-dioxatricyclo[4.3.1.03,7] decan skeleton derived from valepotriates is determined by the acetal chromophore. For the less symmetric ring system of 1,6-anhydro hexapyranoses the sign of this CD is predictable. The vicinal effect for enones and diketones in this series is appreciable. A new rule for the correlation between the CD around 190–205 nm of enol ethers and their absolute conformation is given; the same reasoning is applicable to explain the known rules for cisoid and transoid vinyl cyclo-propanes. 相似文献
20.
Zbigniew J. Witczak Renu Chhabra Dina Boryczewski 《Journal of carbohydrate chemistry》2013,32(4-5):543-553
ABSTRACT β-(1→2)-2,3-Dideoxy-2-C-acetamidomethyl-2-S-thiodisaccharides were synthesized in four steps by a stereoselective base catalyzed Michael addition reaction of 1-thiosugars to α-nitroalkene 4a, a new chiral synthon from levoglucosenone. It was followed by the reduction of the nitro group with a sodium borohydride/cobalt chloride complex and the hydrolytic opening of the 1,6-anhydro ring. 相似文献