Showing papers on "Glycal published in 2015"
TL;DR: Kdo, Kdo glycal, and 2-acetylated Kdo ester were synthesized quickly in high yield from a di-O-isopropylidene derivative of Kdo ethyl ester.
24 citations
TL;DR: This synthetic strategy should be amenable to the chemical synthesis of analogs of derhodinosylurdamycin A bearing diverse 2-deoxy sugar subunits for structure and activity relationship studies.
Abstract: The first total synthesis of derhodinosylurdamycin A, an angucycline antitumor antibiotic, has been described. The synthesis features a Hauser annulation followed by pinacol coupling to construct the tetracyclic angular aglycon, a Stille coupling of glycal stannane and tetracyclic aryliodide followed by stereoselective reduction to afford the 2-deoxy β-C-arylglycoside, and a late-stage stereoselective glycosylation for the preparation of derhodinosylurdamycin A. This synthetic strategy should be amenable to the chemical synthesis of analogs of derhodinosylurdamycin A bearing diverse 2-deoxy sugar subunits for structure and activity relationship studies.
23 citations
TL;DR: The dual-role of ruthenium in sequential glycosylation-oxidation-dihydroxylation is amenable to a wide range of thio acceptors to access α-D-mannopyranosyl sulfones in good yields with high regioselectivity.
Abstract: An efficient and divergent approach to C(2)–C(3) unsaturated glycosyl and α-d-mannopyranosyl sulfones has been developed via ruthenium-promoted direct glycosylation, oxidation, and dihydroxylation from glycal in one-pot. The presence of stoichiometric amounts of NaIO4 and in situ generation of RuO4 from a RuCl3–NaIO4 reagent system were crucial for chemoselective oxidation of sulfide in the presence of an olefin moiety. The dual-role of ruthenium in sequential glycosylation–oxidation–dihydroxylation is amenable to a wide range of thio acceptors to access α-d-mannopyranosyl sulfones in good yields with high regioselectivity.
20 citations
TL;DR: A convergent total synthesis of 16-membered macrolactone natural product (−)-A26771B 1 starting from 3,4,6-tri-O-acetyl-D-glucal 7 is reported in this paper.
Abstract: A convergent total synthesis of a 16-membered macrolactone natural product (−)-A26771B 1 starting from 3,4,6-tri-O-acetyl-D-glucal 7 is reported. The Ferrier rearrangement of acetylated glucal 7, cross metathesis between chiral fragments 3 and 4, Yamaguchi macrolactonization and selective oxidation of the allylic alcohol are the key features of the synthesis.
20 citations
TL;DR: In this paper, the stereoselective synthesis of 2,3-unsaturated S-glycosides was accomplished by using mild and convenient protocol employing a catalytic amount of RuCl3.
14 citations
TL;DR: A highly efficient and mild method for the synthesis of glycosyl sulfonamides andglycosyl amides from glycal has been described using Zn(OTf)2 as an economical and environmentally friendly catalyst.
11 citations
TL;DR: The concise 8-step synthesis of azetidine aldehyde was devised by incorporating the novel strategy for ready access to 3-amino-2,3-dideoxysugars via regio- and stereoselective tandem hydroamination/glycosylation of glycal as the key step.
10 citations
TL;DR: This study describes the development of a novel procedure of glycal fluorophosphorylation applied to the synthesis of a fluorinated analogue of an important bacterial metabolite.
Abstract: This study describes the development of a novel procedure of glycal fluorophosphorylation applied to the synthesis of a fluorinated analogue of an important bacterial metabolite. This procedure was applied to several heptose-derived glycals, and the stereochemical outcome of the reaction was analyzed. Under optimized conditions, the reaction is β-gluco selective, but a significant amount of the α-gluco diastereomer is also generated.
7 citations
TL;DR: The same procedure proved to be appropriate in synthesizing dihydropyran derivatives ('C-glycosides') using allyltrimethylsilane as the nucleophile (only 'α-anomers' were obtained). All new compounds were fully characterized by spectral data, whereas single-crystal X-ray analysis was performed for two thioglycosides.
7 citations
TL;DR: A facile and highly efficient microwave-assisted preparation of Neu5Ac1Me using silica sulfuric acid (SSA) as solid-supported acid catalyst that is one- to two-orders of magnitude faster than standard procedures is reported.
6 citations
TL;DR: Three routes to the synthesis of the title compound, a protected, desmethyl derivative of lemonose, from l-rhamnose or its glycal, were investigated based on electrophilic cyclization, epoxidation-ring opening, and deoxygenation of an intermediate that was used in thehesis of the amino sugar callipeltose.
TL;DR: In this paper, N-alkylated tetrahydropyrano[3,2-c ]quinolines were synthesized via intramolecular Friedel-Crafts alkylation using a 1- O -acetylglucosyl derivative as the key intermediate.
Abstract: Diastereoselective synthesis of novel and enantiopure N-alkylated tetrahydropyrano[3,2- c ]quinolines is described via intramolecular Friedel–Crafts alkylation using a 1- O -acetylglucosyl derivative as the key intermediate. Unprecedented formation of new glycal derivatives and α,β-unsaturated carbaldehyde products is also discussed.
TL;DR: α-2,3-Unsaturated galactosides were synthesized by the initial activation of d-galactals with diethyl phosphorochloridite and the subsequent glycosyl addition via Ferrier rearrangement with various O-nucleophiles in the presence of AlCl3 to give the glycoside products with excellent α-stereoselectivity.
TL;DR: In this paper, a synthetic strategy towards the potent cytostatic agent pluraflavin A has been developed, based on the formation of the enantioenriched anthrapyran core bearing a halogen atom.
Abstract: A synthetic strategy towards the potent cytostatic agent pluraflavin A has been developed. Formation of the enantioenriched anthrapyran core bearing a halogen atom enabled the introduction of the α C-aryl glycoside by Stille cross-coupling and subsequent hydrogenation of the aryl glycal. Chemo- and stereoselective O-glycosylations of α oliose and β 3-epi vancosamine residues afforded a fully glycosylated aromatic core. Attempts to install the dimethylamino group of the C-disaccharide suggest that introduction of an azide group by displacement and subsequent reduction may pave the way to the total synthesis of pluraflavin A.
TL;DR: In this paper, a mild method for the synthesis of glycosyl sulfonamides and amides from glycal is presented using Zn(OTf)2 as an economical and environmentally friendly catalyst.
Abstract: A highly efficient and mild method for the synthesis of glycosyl sulfonamides and glycosyl amides from glycal is presented using Zn(OTf)2 as an economical and environmentally friendly catalyst.
TL;DR: A regio- and stereo-controlled, one-pot amidoglycosylation of alcohols has been achieved using O-acetylated glycals, trichloroethoxysulfonamide, and iodosobenzene in the presence of a rhodium(II) catalyst.
Abstract: A regio- and stereo-controlled, one-pot amidoglycosylation of alcohols has been achieved using O-acetylated glycals, trichloroethoxysulfonamide, and iodosobenzene in the presence of a rhodium(II) catalyst. The reaction would proceed via stereoselective intermolecular aziridination of the glycal.
TL;DR: The stereochemistry of this arylation reaction is controlled by the configuration at C3 of the glycal as discussed by the authors, which is a configuration that was introduced by the authors of this paper.
Abstract: The stereochemistry of this arylation reaction is controlled by the configuration at C3 of the glycal.
TL;DR: A review of 1,2-cyclopropyl car-bohydrates can be found in this paper, where a wide variety of products are obtained depending on the functionality attached to the cyclopropane and the promoter (Lewis acid, Br o nsted acid, halophile or base).
Abstract: Addition of a carbene to a glycal is the prominent method for the synthesis of 1,2-cyclopropyl car- bohydrates. This incorporation of a cyclopropane into a carbohydrate scaffold enables divergent reactivity, with the two main classes being ring expansion and cleavage to 2- C -branched carbohydrates. A wide variety of products are obtained depending on the functionality attached to the cyclopropane (none or ester or hal- ogens) and the promoter (Lewis acid, Br o nsted acid, halophile or base) used in the reaction. This article reviews progress in the synthesis and reactions of 1,2-cyclopropyl carbohydrates since 2000 and discloses efforts by our group in the area.
TL;DR: A copper-mediated fluorofunctionalization of alkenes and alkynes has been developed in this article, which provides ready access to trisubstituted difluoromethylated olefins (from dihydropyrans, glycal derivatives, or terminal alkynes).
Abstract: A copper-mediated fluorofunctionalization of alkenes and alkynes has been developed. This method provides ready access to trisubstituted difluoromethylated olefins (from dihydropyrans, glycal derivatives, or terminal alkynes) or to tetrasubstituted olefins (from disubstituted alkynes). The products were obtained in good to high yields with acceptable E/Z selectivities. Finally, a first direct route to difluoromethylated alkynes is reported, albeit with low yields.