- Stereoselective synthesis of resorcylic acid lactone Cochliomycin B
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The total synthesis of 14-membered resorcylic acid lactone, Cochliomycin B has prescribed, in a convergent manner, from readily available starting materials, D-galactose, L-aspartic acid and ethyl acetoacetate. The key reactions involved in the synthesis are Julia-Kocienski olefination, E-selective Horner-Wadsworth-Emmons olefination and intramolecular lactonization.
- Nagalatha,Siva Ganesh,Venkat Narsaiah
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- Regioselectivity of glycosylation reactions of galactose acceptors: An experimental and theoretical study
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Regioselective glycosylations allow planning simpler strategies for the synthesis of oligosaccharides, and thus reducing the need of using protecting groups. With the idea of gaining further understanding of such regioselectivity, we analyzed the relative
- Del Vigo, Enrique A.,Stortz, Carlos A.,Marino, Carla
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supporting information
p. 2982 - 2989
(2020/01/09)
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- Localization-controlled two-color luminescence imaging: Via environmental modulation of energy transfer in a multichromophoric species
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We prepared a bichromophoric species 1, made of two different bodipy dyes bridged by a d-galactose unit. 1 exhibits different emission spectra when located in different compartments of biological systems, independently of its concentration. This is an unprecedented feature for a single multicomponent molecule and is due to the dependence on the environment of the photoinduced energy transfer process occurring between its bodipy subunits. Therefore, 1 can give useful information about cell composition and ultimately anomalies without requiring the simultaneous use of several different compounds, paving the way for the use of environment-controlled inter-component energy transfer to gain cell information based on luminescence imaging.
- Bonaccorsi, Paola,Papalia, Teresa,Barattucci, Anna,Salerno, Tania M. G.,Rosano, Camillo,Castagnola, Patrizio,Viale, Maurizio,Monticone, Massimiliano,Campagna, Sebastiano,Puntoriero, Fausto
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supporting information
p. 4733 - 4738
(2018/04/03)
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- A novel O-fucosylation strategy preactivated by (p-Tol)2SO/Tf2O and its application for the synthesis of Lewis blood group antigen Lewisa
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Based on a preactivation strategy using (p-Tol)2SO/Tf2O, a new O-fucosylation method with thioglycoside as donor under mild conditions was reported. High yields and excellent α-stereoselectivities of the fucosylation were obtained wi
- Li, Cui-yun,Liu, Guang-jian,Du, Wei,Zhang, Yuan,Xing, Guo-wen
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supporting information
p. 2109 - 2112
(2017/05/09)
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- Allylic Azide Rearrangement in Tandem with Huisgen Cycloaddition for Stereoselective Annulation: Synthesis of C-Glycosyl Iminosugars
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Allylic azide rearrangement is used in tandem with intramolecular azide-alkene cycloaddition to give a triazoline that when subsequently decomposed in the presence of a nucleophile gives piperidines. The tandem reaction gives two stereocenters that are generated with high control. The formation of the piperidines required the presence of innate conformational constraint. The applicability of the annulation reaction is demonstrated by the synthesis of iminosugars. A proposal is included to account for the observed stereoselectivity, which is influenced by the precursor structure.
- Moynihan, Lorna,Chadda, Rekha,McArdle, Patrick,Murphy, Paul V.
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supporting information
p. 6226 - 6229
(2016/01/09)
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- Linearization of carbohydrate derived polycyclic frameworks
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We report easy access to carbohydrate derived diverse tricyclic skeletons which could be beneficial for exploring polyfunctionalized chiral alicycles. The key reaction to assemble a sugar fused tricyclic core is intermolecular tandem esterification and 1,3-dipolar cycloaddition. The framework was elaborated using amide forming reactions, opening of isoxazolidine rings followed by N and O-acylations. The sequences provide distinct, spatially separated and encoded chemical entities that may pave the way to investigate cell functions.
- Singh, Priyanka,Panda, Gautam
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p. 31892 - 31903
(2014/08/18)
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- Lipases in the regioselective preparation of glyceric acid esters of methyl glycosides
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The lipase-catalyzed regioselective acylation of methyl α-D-galacto-, -gluco- and -mannopyranosides with isopropylidene-protected (R)- and (S)-glyceric acid methyl esters in organic solvents is presented. Factors affecting the formation of the 6-O-mono- and 2,6-O-diacylated products are examined and preparative-scale reactions are detailed. In addition, studies on partially protected methyl α-D-galactopyranosides are presented, with the 3,4-O-isopropylidene protected compound leading exclusively to the formation of the 6-O-monoacylated product even at high substrate concentrations. Application of acidic resin in methanol allows removal of the isopropylidene protection groups without disturbing the ester bond at C-6. Copyright
- Sundell, Riku,Kanerva, Liisa T.
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supporting information
p. 4971 - 4978
(2013/08/23)
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- Nano n-propylsulfonated magnetic γ-Fe 2O 3 as an efficient and reusable catalyst for the synthesis O-isopropylidene derivatives of carbohydrates
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Nano n-propylsulfonated γ-Fe2O3 was found to be a highly efficient, reusable heterogeneous catalyst for the conversion of a range of monosaccharides and some of their derivatives to the corresponding O-isopropylidene derivatives in good to excellent yields by refluxing the reaction mixture in dry acetone. The magnetic property of the catalyst enabled its separation from the reaction mixture by a simple process of filtration along with the aid of an external magnet. The efficiency of the catalyst was found to be largely unaffected for at least up to six cycles of reuse, thus proving the new methodology to be environmentally rewarding besides being simple and facile in operation.
- Zhang, Xiaoran,Zhang, Changqiang
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p. 249 - 258
(2013/08/15)
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- Hydroxy group acidities of partially protected glycopyranosides
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A comprehensive acidity study of carbohydrate hydroxy groups has been carried out. Relative acidities (Ke) were determined spectrophotometrically for partially methylated methyl α-D- glycopyranosides. Apparently, the acidity is strongly affected by intramolecular hydrogen bonding as well as stereochemistry and solvation. By comparison with pKe and pKa values of aliphatic alcohols and polyols the first estimation of the pKa values for partially protected glycopyranosides was obtained. These findings contribute to the understanding of the relative reactivities of carbohydrate hydroxy groups.
- Matwiejuk, Martin,Thiem, Joachim
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experimental part
p. 2180 - 2187
(2012/06/30)
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- A chiron approach to aminocytitols by petasis-borono-mannich reaction: Formal synthesis of (+)-conduramine e and (-)-conduramine e
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A chiron approach to a stereoselective route for the synthesis of aminocytitols from carbohydrates is described. The formal synthesis of (+)-conduramine E and (-)-conduramine E was achieved by utilizing this strategy. The key features of the synthetic strategy include one-pot three-component Petasis-Borono-Mannich reaction to introduce the syn-β-amino alcohol functionality of conduramine E and ring-closing metathesis to construct its carbocyclic core. The present synthetic approach paves the way for stereoselective synthesis of several conduramines starting from carbohydrates.
- Ghosal, Partha,Shaw, Arun K.
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supporting information
p. 7627 - 7632,6
(2020/08/24)
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- O-Isopropylidenation of carbohydrates catalyzed by vanadyl triflate
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Vanadyl triflate has been identified as a mild and efficient catalyst for the chemoselective O-isopropylidenation of functionalized carbohydrates with acetone and acetone equivalents. The current protocol is compatible with a diverse array of protecting groups and the products can be readily isolated by simple aqueous wash.
- Lin, Chun-Cheng,Jan, Mi-Dan,Weng, Shiue-Shien,Lin, Chang-Ching,Chen, Chien-Tien
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p. 1948 - 1953
(2007/10/03)
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- Regiospecific synthesis of 4-deoxy-D-threo-hex-3-enopyranosides by simultaneous activation-elimination of the talopyranoside axial 4-OH with the NaH/Im2SO2 system: Manifestation of the stereoelectronic effect
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A new and high-yielding method for the regioselective preparation of 4-deoxy- and 2,4-dideoxy-2-acetamido-β-D-threo-hex-3-enopyranosides has been developed. The process involves a simultaneous activation-elimination of the OH-4 group of β-D-talopyranoside
- Attolino, Emanuele,Catelani, Giorgio,D'Andrea, Felicia
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p. 5279 - 5292
(2007/10/03)
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- Synthesis of Globotriaosylceramide (Gb3) and Isoglobotriaosylceramide (isoGb3)
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The synthesis of globotriaosylceramide (1) was based on O-galactosyl trichloroacetimidate 5α as donor and 4b-O-unprotected lactose 7 as acceptor; 7 was readily accessible from lactose.Glycosylation by an "inverted procedure" afforded preferentially the α-
- Qiu, Dongxu,Schmidt, Richard R.
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p. 217 - 224
(2007/10/02)
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- Meta-chloroperbenzoic acid as a selective reagent for the removal of O-propenyl groups. Its use in the synthesis of some d-galactopyranoside and 4-deoxy-1-threo-4-hexenopyranoside derivatives
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Meta-chloroperbenzoic acid can be used as a mild and selective reagent for the removal of the O-propenyl group in the deprotection sequence of allyl protected hydroxyl functions. Its use is illustrated in four synthetic pathways, leading, respectively, to
- Barili,Berti,Bertozzi,Catelani,Colonna,Corsetti,D'Andrea
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p. 5365 - 5376
(2007/10/02)
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- Novel synthesis of monosulphated methyl α-D-galactopyranosides
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The syntheses of the methyl α-D-galactopyranoside 2-,3-,4-, and 6-sulphates (11, 12, 16, and 21 respectively) have been achieved using trimethylamine - sulphur trioxide as a sulphating agent.The procedure used is high yielding and requires shorter reactio
- Rashid, Abdul,Mackie, William,Colquhoun, Ian J.,Lamba, Doriano
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p. 1122 - 1127
(2007/10/02)
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- NEW RESULTS IN THE ISOPROPYLIDENATION OF GALACTOPYRANOSIDES. USEFUL INTERMEDIATES FOR THE SYNTHESIS OF GALACTOSE DERIVATIVES.
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Reaction of several α- and β-galactopyranosides with 2,2-dimethoxypropane produced up to five types of mono-, bis-, and tris(isopropylidene)acetals, among which the 3,4-O-isopropylidene-6-O-(2-methoxyisopropyl) derivatives can be obtained in high yield an
- Barili, Pier Luigi,Berti, Giancarlo,Catelani, Giorgio,Colonna, Fabrizia,Marra, Alberto
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p. 2307 - 2310
(2007/10/02)
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- The Deoxygenation of Some Carbohydrate Diols via Derived Cyclic Thiocarbonate
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The treatment of methyl 2,6-di-O-methyl-3,4-O-thiocarbonyl-β-D-galactoside with methyl iodide gives mainly the 3-deoxy-3-iodo-D-guloside, whereas the α-anomer of the above and methyl 2-O-methyl-3,4-O-thiocarbonyl-β-L-arabinoside give mainly the 4-deoxy-4-
- Patroni, Joseph J.,Stick, Robert V.,Engelhardt, Lutz M.,White, Allan H.
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p. 699 - 711
(2007/10/02)
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- Preparation of Some Partially Methylated Galactosides from Methyl α-D-Galactopyranoside
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Methyl 2,3,6-tri-O-methyl-α-D-galactopyranoside (3) and methyl 2,6-di-O-methyl-α-D-galactopyranoside (2) have been synthesized starting from isopropylidene derivatives of methyl α-D-galactopyranoside.
- Roy, Abhijit,Batavyal, Lakshmi,Roy, Nirmolendu
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p. 498 - 499
(2007/10/02)
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- Use of Ferric Chloride in Carbohydrate Reactions: Part III-Reaction of Methyl Glycosides and Methyl 6-O-Tosyl Glycosides with Ferric Chloride-Acetone
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Ferric chloride-acetone has been used for the preparation of O-isopropylidene derivates of methyl glycosides and methyl 6-O-tosyl glycosides.Using this reagent 1,2:5,6-di-O-isopropylidene-α-D-glucofuranose, methyl 4,6-O-isopropylidene-α-D-glucopyranoside, methyl 2,3-O-isopropylidene-α-D-galactopyranoside, methyl 4,6-O-isopropylidene-α-D-galactopyranoside, 1,2:3,4-di-O-isopropylidene-α-D-galactopyranose,1,2:3,5-di-O-isopropylidene-6-O-tosyl-α-D-glucofuranose, 1,2:3,4-di-O-isopropylidene-6-O-tosyl-α-D-galactopyranose and methyl 3,4-O-isopropylidene-6-O-tosyl-α-D-galactopyranoside have been prepared.Inhibition by tosyl group in the hydrolysis of the glycosidic function has been rationalised.
- Dasgupta, F.,Singh, P. P.,Srivastava, H. C.
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p. 1056 - 1059
(2007/10/02)
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