- ALTERNATIVE, SIMPLE ROUTE TO HYDROXYMETHYL CROWN ETHERS
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Components for polymer-supported catalysts, hydroxymethyl-substituted 15-crown-5 and 18-crown-6 were prepared from readily available starting materials on relative simple way.
- Ctech, Bronislav
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- SYNTHESIS OF 2,3-DI-O-PHYTANYL-1-O-6)-MANNOSYL-α(1->2)-GLUCOSYL-α(1->1)>-SN-GLYCEROL. PURPLE MEMBRANE GLYCOLIPIDS
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A convenient approach to the synthesis of triglycosyl-2,3-di-O-phytanyl-sn-glycerols will be presented.Special attention will be paid to the use of the following protective groups in carbohydrate chemistry: the 2,2,2-trichloroethoxycarbonyl, the 1,1,3,3-tetraisopropyldisiloxane-1,3-diyl and the o-dibromomethyl benzoyl group.
- Boeckel, C. A. A. van,Westerduin, P.,Boom, J. H. van
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- Synthesis and vesicle formation from dimeric pseudoglyceryl lipids with (CH2)m spacers: Pronounced m-value dependence of thermal properties, vesicle fusion, and cholesterol complexation
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Eight new dimeric lipids, in which the two Me2N+ ion headgroups are separated by a variable number of polymethylene units [-(CH2)m-], have been synthesized. The electron micrograph (TEM) and dynamic light scattering (DLS) of their aqueous dispersions confirmed the formation of vesicular-type aggregates. The vesicle sizes and morphologies were found to depend strongly on the m value, the method, and thermal history of the vesicle preparation. Information on the thermotropic properties of the resulting vesicles was obtained from microcalorimetry and temperature-dependent fluorescence anisotropy measurements. Interestingly, the Tm values for these vesicles revealed a nonlinear dependence on spacer chain length (m value). These vesicles were able to entrap riboflavin. The rates of permeation of the OH- ion under an imposed transmembrane pH gradient were also found to depend significantly on the m value. X-Ray diffraction of the cast films of the lipid dispersions elucidated the nature and the thickness of these membrane organizations, and it was revealed that these lipids organize in three different ways depending on the m value. The EPR spin-probe method with the doxylstearic acids 5NS, 12NS, and 16NS, spin-labeled at various positions of stearic acid, was used to establish the chain-flexibility gradient and homogeneity of these bilayer assemblies. The apparent fusogenic propensities of these bipolar tetraether lipids were investigated in the presence of Na2SO4 with fluorescence-resonance energy-transfer fusion assay. Small unilamellar vesicles formed from 1 and three representative biscationic lipids were also studied with fluorescence anisotropy and 1H NMR spectroscopic techniques in the absence and the presence of varying amounts of cholesterol.
- Bhattacharya, Santanu,De, Soma
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- Synthesis of macrocyclic diacyl/dialkyl glycerols containing disulfide tether and studies of their effects upon incorporation in DPPC membranes. Implications in the design of phospholipase A2 modulators
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A general method for the preparation of novel disulfide-tethered macrocyclic diacylglycerols (DAGs) has been described. Overall synthesis involved stepwise protection, acylation, and deprotection to yield the bis(ω-bromoacyl) glycerols. In the crucial macrocyclization step, a unique reagent, benzyltriethylammonium tetrathiomolybdate (BTAT), has been used to convert individual bis(ω-bromoacyl) glycerols to their respective macrocyclic disulfides. DAG 6, which had ether linkages between hydrocarbon chains and the glycerol backbone, was also synthesized from an appropriate precursor using a similar protocol. One of the DAGs (DAG 5) had a carbon- carbon tether instead of a disulfide one and was synthesized using modified Glaser coupling. Preparation of α-disulfidetethered DAG (DAG 4) required an alternative method, as treatment of the bisbromo precursor with BTAT gave a mixture of several compounds from which separation of the target molecule was cumbersome. To avoid this problem, the bisbromide was converted to its corresponding dithiocyanate, which on further treatment with BTAT yielded the desired DAG (DAG 4) in good yield. Upon treatment with the reducing agent dithiothreitol (DTT), the DAGs that contain a disulfide tether could be quantitatively converted to their 'open-chain' thiol analogues. These macrocyclic DAGs and their reduced 'open-chain' analogues have been incorporated in DPPC vesicles to study their effect on model membranes. Upon incorporation of DAG 1 in DPPC vesicles, formation of new isotropic phases was observed by 31P NMR. These isotropic phases disappeared completely on opening the macrocyclic ring by a reducing agent. The thermotropic properties of DPPC bilayers having DAGs (1-6) incorporated at various concentrations were studied by differential scanning calorimetry. Incorporation of DAGs in general reduced the cooperativity unit (CU) of the vesicles. Similar experiments with reduced 'open-chain' DAGs incorporated in a DPPC bilayer indicated a recovery of CU with respect to their macrocyclic 'disulfide' counterparts. The effect of inclusion of these DAGs on the activity of phospholipase A2 (PLA2) was studied in vitro. Incorporation of DAG 1 in DPPC membranes potentiated both bee venom and cobra venom PLA2 activities.
- Bhattacharya, Santanu,Ghosh, Sangita,Easwaran, Kalpathy R. K.
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- Percarboxylic Acid Oxidation of α-Hydroxy-Substituted Alkoxyallenes: The Unexpected Formation of Acyloxy-Substituted 1,2-Diketones and the Synthesis of Functionalized Quinoxalines
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Treatment of α-hydroxy-substituted methoxyallene derivatives with meta-chloroperbenzoic acid provided acyloxy-substituted 1,2-diketones in moderate yields. A mechanism for the formation of these unexpected products is proposed. The configuration of the enantiopure compound (S)-1-(3-methylquinoxalin-2-yl)-1-(4-nitrobenzoyl?oxy)propan-2-yl 3-chlorobenzoate - determined by X-ray crystal structure analysis - indicates the intermediacy of a carbenium ion during formation of the 1,2-diketones. The functionalized 1,2-diketones are valuable starting materials for a variety of products as demonstrated by the synthesis of quinoxalines, an imidazole derivative, and electron-deficient alkenes.
- Klemme, Robby,Bentz, Christoph,Zukowski, Tomasz,Schefzig, Luise,Lentz, Dieter,Reissig, Hans-Ulrich,Zimmer, Reinhold
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- Synthesis and vesicle formation from novel pseudoglyceryl dimeric lipids. Evidence of formation of widely different membrane organizations with exceptional thermotropic properties
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Eight new bis-cationic dimeric lipids 2a-h have been synthesized; TEM of their aqueous dispersions confirmed the vesicle formation and from the thermal, spectroscopic, DLS and XRD studies it has been revealed that they form three different kinds of membranous aggregate depending on the m-value.
- Bhattacharya, Santanu,De, Soma,George, Shaji K.
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- Dendritic Oligoglycerol Regioisomer Mixtures and Their Utility for Membrane Protein Research
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Dendrons are an important class of macromolecules that can be used for a broad range of applications. Recent studies have indicated that mixtures of oligoglycerol detergent (OGD) regioisomers are superior to individual regioisomers for protein extraction. The origin of this phenomenon remains puzzling. Here we discuss the synthesis and characterization of dendritic oligoglycerol regioisomer mixtures and their implementation into detergents. We provide experimental benchmarks to support quality control after synthesis and investigate the unusual utility of OGD regioisomer mixtures for extracting large protein quantities from biological membranes. We anticipate that our findings will enable the development of mixed detergent platforms in the future.
- Urner, Leonhard H.,Goltsche, Katharina,Selent, Marleen,Liko, Idlir,Schweder, Marc-Philip,Robinson, Carol V.,Pagel, Kevin,Haag, Rainer
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p. 2537 - 2542
(2020/12/30)
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- Synthesis and catalytic evaluation of acidic carbons in the etherification of glycerol obtained from biodiesel production
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In this paper, the catalytic behaviour of carbonaceous system (Ccs) functionalized with –SO3H groups were studied in the etherification of refined (Gly) and crude glycerol (GlyC), with benzyl alcohol (BA). This Ccs was obtained by a synthetic method with low energetic cost in only 24 h. Its catalytic activity and selectivity were studied varying the catalyst percentage (2.5, 5 and 10 wt.%), the initial reactant molar ratio and temperature (between 80 and 120 °C). A very good catalytic performance was achieved (97 % conversion after 360 min of reaction), at 120 °C, Gly:BA = 3:1 and 10 wt.% of Ccs. The high activity can be attributed to high acid site density (6.4 mmol H+/g), that also allowed us to working at lower reaction temperature (100 °C) and with less catalyst concentration (2.5 wt.%), without observing significant loss in BA conversion. Monoether (ME1) was the major product of the reaction with 72 % selectivity. The material can be reused and still gives a notable conversion of BA (about 43 %) after three successive reuses. Finally, the Ccs was active and selective to the desired products in the etherification of crude glycerol (GlyC) derived of biodiesel industry. An important BA conversion (45 %) was obtained only reducing the water content of GlyC and without carrying out any other purification and/or neutralization treatment.
- Chiosso, María E.,Casella, Mónica L.,Merlo, Andrea B.
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p. 107 - 114
(2020/10/29)
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- Selective monochlorination of unsymmetrical vicinal diols with chlorinated iminium chlorides
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Chlorinated iminium chlorides have been identified to promote the highly efficient and selective mono-chlorination of unsymmetrical vicinal diols. Vilsmeier reagent, namely, (chloromethylene)dimethyliminium chloride, enables highly reactive and regioselective chlorination of 1,2- and 1,3-diols featured one secondary benzylic hydroxy group and one primary aliphatic hydroxy group to give the corresponding 1,2- and 1,3-chlorohydrins. Viehe's salts (α,α-dichloro iminium salts) exhibit excellent reactivity and good selectivity for vicinal diols to give the corresponding chlorohydrin carbamates via a cyclic intermediate in situ. The chlorination protocols tolerate diverse functional groups, including halogens, naphthalene rings, nitro, and cyano. Moreover, the optical purity of chiral diols could be retained during this chlorination reaction.
- Li, Chengyang,Li, Xiaotong,Wang, Yu,Wu, Xiaoyu,Xie, Xiaomin,Yang, Liqun,Zhang, Zhaoguo
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supporting information
(2020/03/23)
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- POLY(PHOSPHOESTERS) FOR DELIVERY OF NUCLEIC ACIDS
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Disclosed are polymers comprising the moiety A, which is a moiety of formula I: and pharmaceutically acceptable salts thereof, wherein R, R1, R2, L, n1 and n2 are as defined herein. These polymers are useful for delivering nucleic acids to subject. These polymers and pharmaceutically acceptable compositions comprising such polymers and nucleic acids can be useful for treating various diseases, disorders and conditions.
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- COMPOSITIONS AND METHODS FOR THE TREATMENT OF PARKINSON'S DISEASE
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The invention relates to the compounds of formula I, formula II and/or formula III or its pharmaceutical acceptable salts, as well as polymorphs, solvates, enantiomers, stereoisomers and hydrates thereof. The pharmaceutical compositions comprising an effective amount of compound of formula I, formula II or formula III, and methods for treating or preventing Parkinson's disease may be formulated for oral, buccal, rectal, topical, transdermal, transmucosal, intravenous, parenteral administration, subcutaneous, depot, intramuscular, syrup, or injection. Such compositions may be used to treatment or management of Parkinson's disease as well as scleroderma, restless leg syndrome, hypertension and gestational hypertension.
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- HYDROPHOBIC ACID ADDITION SALTS AND PHARMACEUTICAL FORMULATIONS THEREOF
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The invention provides hydrohphobic drug salts and pharmaceutical compositions comprising such salts. The invention fourther provides compositions for delivering poorly soluble drugs, including hydrophobic drug salts.
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- Site-Selective Mono-Oxidation of 1,2-Bis(boronates)
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Site-selective oxidation of vicinal bis(boronates) is accomplished through the use of trimethylamine N-oxide in 1-butanol solvent. The reaction occurs with good efficiency and selectivity across a range of substrates, providing 2-hydro-1-boronic esters which are shown to be versatile intermediates in the synthesis of chiral building blocks.
- Yan, Lu,Morken, James P.
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p. 3760 - 3763
(2019/05/24)
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- Preparation of benzothiazolyl-decorated nanoliposomes
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Amyloid β (Aβ) species are considered as potential targets for the development of diagnostics/therapeutics towards Alzheimer’s disease (AD). Nanoliposomes which are decorated with molecules having high affinity for Aβ species may be considered as potential carriers for AD theragnostics. Herein, benzothiazolyl (BTH) decorated nanoliposomes were prepared for the first time, after synthesis of a lipidic BTH derivative (lipid-BTH). The synthetic pathway included acylation of bis(2-aminophenyl) disulfide with palmitic acid or palmitoyl chloride and subsequent reduction of the oxidized dithiol derivative. The liberated thiols were able to cyclize to the corresponding benzothiazolyl derivatives only after acidification of the reaction mixture. Each step of the procedure was monitored by HPLC analysis in order to identify all the important parameters for the formation of the BTH-group. Finally, the optimal methodology was identified, and was applied for the synthesis of the lipid-BTH derivative. BTH-decorated nanoliposomes were then prepared and characterized for physicochemical properties (size distribution, surface charge, physical stability, and membrane integrity during incubation in presence of buffer and plasma proteins). Pegylated BTH-nanoliposomes were demonstrated to have high integrity in the presence of proteins (in comparison to non-peglated ones) justifying their further exploitation as potential theragnostic systems for AD.
- Mourtas, Spyridon,Christodoulou, Panayiota,Klepetsanis, Pavlos,Gatos, Dimitrios,Barlos, Kleomenis,Antimisiaris, Sophia G.
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- Glycerol conversion to high-value chemicals: The implication of unnatural α-amino acid syntheses using natural resources
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Glycerol derivatives are an important class of compounds, which have great applications as basic structural building blocks in organic synthesis. O-Benzylglycerol was oxidised to produce a high-value compound in high yield using a NaOtBu-O2 system. Furthermore, the synthetic utility of the resulting product was demonstrated by its transformation into unnatural α-amino acids, thus showing the valorisation of glycerol biomass.
- Park, Yun Ji,Yang, Jung Woon
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supporting information
p. 2615 - 2620
(2019/06/03)
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- Regioselective Ring-Opening of Glycidol to Monoalkyl Glyceryl Ethers Promoted by an [OSSO]-FeIII Triflate Complex
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A FeIII-triflate complex, bearing a bis-thioether-di-phenolate [OSSO]-type ligand, was discovered to promote the ring-opening of glycidol with alcohols under mild reaction conditions (0.05 mol % catalyst and 80 °C). The reaction proceeded with high activity (initial turnover frequency of 1680 h?1 for EtOH) and selectivity (>95 %) toward the formation of twelve monoalkyl glyceryl ethers (MAGEs) in a regioselective fashion (84–96 % yield of the non-symmetric regioisomer). This synthetic approach allows the conversion of a glycerol-derived platform molecule (i.e., glycidol) to high-value-added products by using an Earth-crust abundant metal-based catalyst.
- Monica, Francesco Della,Ricciardi, Maria,Proto, Antonio,Cucciniello, Raffaele,Capacchione, Carmine
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p. 3448 - 3452
(2019/08/01)
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- Hydrogenation of CO2-Derived Carbonates and Polycarbonates to Methanol and Diols by Metal–Ligand Cooperative Manganese Catalysis
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The first base-metal-catalysed hydrogenation of CO2-derived carbonates to alcohols is presented. The reaction proceeds under mild conditions in the presence of a well-defined manganese complex with a loading as low as 0.25 mol %. The non-precious-metal homogenous catalytic system provides an indirect route for the conversion of CO2 into methanol with the co-production of value-added (vicinal) diols in yields of up to 99 %. Experimental and computational studies indicate a metal–ligand cooperative catalysis mechanism.
- Zubar, Viktoriia,Lebedev, Yury,Azofra, Luis Miguel,Cavallo, Luigi,El-Sepelgy, Osama,Rueping, Magnus
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supporting information
p. 13439 - 13443
(2018/09/21)
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- Synthetic method of alkynyl-modified phospholipid derivative for preparing functional phospholipid giant vesicle
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The invention discloses a synthetic method of an alkynyl-modified phospholipid derivative for preparing a functional phospholipid giant vesicle. The method comprises the following steps: with solketalas a starting raw material, selectively introducing an alkyl chain through benzyl protection, deprotection and DCC-DMAP catalytic condensation, synthesizing 3-hydroxy-1,2- dipalmitin, using 2-chloro-2-oxo-1,3,2-dioxaphospholane as a phosphorylation reagent, carrying out ring opening reaction by using 1-dimethylamine-2-allylene, and preparing the alkynyl-modified phospholipid derivative. The method is simple in synthetic route, a highly toxic reagent does not need to be used, and the phospholipid giant vesicle with an adjustable surface reactivity group density can be prepared by mixing the obtained alkynyl-modified phospholipid derivative and common phospholipid available in the market according to a certain proportion. The possibility is provided for the further stabilization and functionalization of this type of the vesicle.
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- Synthesis process of novel compound phosphatidyl 3-hydroxypropionitrile
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The invention relates to a synthesis process of a novel compound phosphatidyl 3-hydroxypropionitrile. The synthesis process comprises the following steps: using acetone glycerol as a starting material; protecting exposed hydroxyl with benzyl; removing a ketal protecting group to obtain two exposed hydroxyls; then, esterifying with stearic acid; removing benzyl protection to obtain the exposed hydroxyl; reacting with a chlorophosphine compound to obtain a phosphine oxide compound; oxidizing to obtain phosphine oxide; and removing one molecular propyl nitrile to obtain a final product phosphatidyl 3-hydroxypropionitrile.
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- Copper-catalyzed/mediated borylation reactions of epoxides with diboron reagents: access to β-hydroxyl boronic esters
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We report the first copper-catalyzed/mediated borylative ring opening reaction of epoxides. This process represents a direct borylative C(sp3)-O bond cleavage of terminal epoxide substrates with commercially available diboron reagents. A wide range of epoxides with different functional groups are involved, and were subsequently converted to the corresponding β-hydroxyl boronic esters smoothly. Moreover, the ring opening product β-pinacol boronate alcohol provided a more beneficial approach for the formation of C-C and C-N bonds.
- Ahmed, Ebrahim-Alkhalil M. A.,Lu, Xi,Gong, Tian-Jun,Zhang, Zhen-Qi,Xiao, Bin,Fu, Yao
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p. 909 - 912
(2017/01/17)
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- Asymmetric hydrolysis of styrene oxide by PvEH2, a novel Phaseolus vulgaris epoxide hydrolase with extremely high enantioselectivity and regioselectivity
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A novel EH from Phaseolus vulgaris, PvEH2, was discovered based on the computer-aided analysis, and its encoding gene was cloned and expressed in E. coli Rossetta (DE3). The substrate spectrum of recombinant (re) PvEH2 was assayed, among which the enantiomeric ratio of rePvEH2 towards racemic styrene oxide (rac-1a) was > 200, while its regioselectivity coefficients, αS and βR, towards (S)- and (R)-1a were 99.1 and 69.8%, respectively. The asymmetric hydrolysis of 20 mM rac-1a by rePvEH2-expressing whole cells was performed at 25 °C, retaining (R)-1a with > 99.5% ees and 49.4% yield and producing (R)-phenyl-1,2-ethanediol (1b) with 96.2% eep and 49.7% yield in 40 min.
- Li, Chuang,Hu, Die,Zong, Xun-Cheng,Deng, Chao,Feng, Lei,Wu, Min-Chen,Li, Jian-Fang
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- Synthesis, Characterization and Catalytic Application of Pyridine-Bridged N-Heterocyclic Carbene–Ruthenium Complexes in the Hydrogenation of Carbonates
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A series of bulky pyridine-bridged NHC–Ru complexes have been rationally designed and synthesized; these exhibited very high catalytic activity in the hydrogenation of cyclic and linear carbonates under mild reaction conditions. In the presence of catalytic amounts of a weak base, a broad range of substrates with different ring size and steric bulk were well tolerated, providing methanol and the corresponding diols in excellent yields with a catalyst loading as low as 0.5 mol %.
- Chen, Jiangbo,Zhu, Haibo,Chen, Jinjin,Le, Zhang-Gao,Tu, Tao
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supporting information
p. 2809 - 2812
(2017/10/23)
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- Efficient diastereoselective synthesis of a new class of azanucleosides: 2′-homoazanucleosides
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Azanucleosides, sugar-modified nucleoside analogues containing a 4′ nitrogen atom, have shown a lot of therapeutic potential, e.g. as anti-cancer and antiviral agents. We report the synthesis of a series of 2’-homoazanucleosides, in which the nucleobase is attached to the 2’-position of the pyrrolidine ring via a methylene linker. A suitable orthogonally protected iminosugar was synthesized by ring closing metathesis and dihydroxylation as key steps and further converted to a series of 8 nucleoside analogues through Mitsunobu reaction with suitably protected nucleobases. The 5′ position of the adenine analogue was then further derivatized with thiols to afford 2 additional compounds. The final compounds were evaluated for biological activity.
- Bouton, Jakob,Van Hecke, Kristof,Van Calenbergh, Serge
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p. 4307 - 4316
(2017/06/30)
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- COMPOSITIONS AND METHODS FOR DELIVERY OF THERAPEUTIC AGENTS
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This disclosure provides improved lipid-based compositions, including lipid nanoparticle compositions, and methods of use thereof for delivering agents in vivo including nucleic acids and proteins. These compositions are not subject to accelerated blood clearance and they have an improved toxicity profile in vivo.
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- Synthesis and immunological study of a wall teichoic acid-based vaccine against E. faecium U0317
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A repeat unit of cell wall teichoic acids (WTA) isolated from E. faecium U0317 was chemically synthesized efficiently by a stepwise strategy. It was derivatized with a 5-aminopentanyl linker to facilitate conjugation with carrier proteins KLH and HSA. Immunological studies of the KLH conjugate 1 demonstrated that it could provoke robust immune responses and high titers of IgG antibodies, which could successfully recognize the synthesized WTA repeat unit 3. This result suggested that synthetic glycoconjugate 1 could be a promising vaccine candidate against E. faecium for further studies.
- Zhou, Zhifang,Ding, Wenzhang,Li, Chen,Wu, Zhimeng
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p. 205 - 219
(2017/11/15)
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- A 1,2-O-double-hexadecyl-rac-glycerol synthesis method (by machine translation)
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The invention discloses a 1,2-O-double-hexadecyl-rac-glycerol synthesis method, comprises first acetone mixed with the glycerine, to the toluene sulfonic acid as catalyst synthesis acetone compression glycerin, and then the acetone compression glycerin C1 hydroxy benzyl protection for 1-phenylmethyl -2,3-isopropylidene-rac-glycerin, then using a certain concentration of hydrochloric acid deprotected, to obtain 3-benzyloxy -1,2-propylene glycol, with the bromo-hexadecane william abdicates reaction occurred 1-O-benzyl -2,3-O-twenty-six alkyl glycerin, finally the hydrogen obtained remove benzyl under the action of a Pd 1,2-O-double-hexadecyl-rac-glycerin. The present invention provides a new synthetic 1,2-O-double-hexadecyl-rac-glycerin ways. (by machine translation)
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Paragraph 0065; 0066
(2016/10/17)
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- Synthesis of Monoalkyl Glyceryl Ethers by Ring Opening of Glycidol with Alcohols in the Presence of Lewis Acids
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The present work deals with the production of monoalkyl glyceryl ethers (MAGEs) through a new reaction pathway based on the reaction of glycidol and alcohols catalyzed by Lewis acid-based catalysts. Glycidol is quantitatively converted with high selectivity (99 %) into MAGEs under very mild reaction conditions (80 °C and 0.01 mol % catalyst loading) in only 1 h using Al(OTf)3 or Bi(OTf)3 as catalyst. The proposed method enhances the choice of possible green synthetic approaches for the production of value-added products such as MAGEs.
- Cucciniello, Raffaele,Ricciardi, Maria,Vitiello, Rosa,Di Serio, Martino,Proto, Antonio,Capacchione, Carmine
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p. 3272 - 3275
(2016/12/16)
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- Aerobic Acetoxyhydroxylation of Alkenes Co-catalyzed by Organic Nitrite and Palladium
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An aerobic acetoxyhydroxylation of alkenes cooperatively catalyzed by organic nitrite and palladium at room temperature using clean and cheap air as the sole oxidant has been developed. Various vicinal diols, diacetoxyalkanes, and dihalogenoalkanes have been synthesized. The gram-scale synthesis has also been approached. Vicinal difluorination and dichlorolation products have also been achieved via this reaction.
- Chen, Xian-Min,Ning, Xiao-Shan,Kang, Yan-Biao
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supporting information
p. 5368 - 5371
(2016/11/02)
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- Chemo- and Regioselective Functionalization of Polyols through Catalytic C(sp3)-C(sp3) Kumada-Type Coupling of Cyclic Sulfate Esters
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This contribution describes a copper-catalyzed, C(sp3)-C(sp3) cross-coupling reaction of cyclic sulfate esters, a distinct class of electrophilic derivatives of polyols, with alkyl Grignard reagents to afford functionalized alcohol products in good yields. The method is operationally simple and highlights the potential of cyclic sulfate esters as highly reactive substrates in catalytic, chemoselective polyol transformations.
- Ramírez-Contreras, Rodrigo,Morandi, Bill
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supporting information
p. 3718 - 3721
(2016/08/16)
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- Synthesis of Novel C-Pivot Lariat 18-Crown-6 Ethers and Their Efficient Purification
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The syntheses of various lariat ethers including several not previously reported and their efficient purification are presented. The synthesis route brings together reactions from a variety of previous works leading to a robust and generalized approach to these C-pivot lariats. The main steps are condensation of functionalized diols with pentaethylene glycol ditosylate in the presence of potassium as a templating cation. Purification of the final products was achieved without chromatography by extracting from an aqueous potassium hydroxide solution.
- Jana, Susovan,Suresh, Vallabh,Lepore, Salvatore D.
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p. 1977 - 1980
(2015/09/01)
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- Glycerol etherification with benzyl alcohol over sulfated zirconia catalysts
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Glycerol (GLY) etherification with benzyl alcohol (BA) was conducted with different zirconia-based heterogeneous acid catalysts, aiming to produce mono- (ME) and dibenzyl glycerol ethers (DE). Physicochemical properties of the prepared catalysts were obtained through XRD, SEM and adsorption of ammonia. The catalytic tests were performed at different temperatures (120-140°C) and initial reactant mass ratios (GLY:BA 1:1 and 2:1). The highest BA conversions were obtained with the catalyst having the highest sulfuric acid content (2S/ZrO2). An increase in the reaction temperature and the GLY:BA initial mass ratio led to an increase in the BA conversion. Two kinetic models (a potential and a hyperbolic approach) were proposed to describe the process performance, including not only reactants evolution with time, but also that of ME, DE and the undesired self-condensation product of BA (benzyl ether, BE). Kinetic parameters for each model were estimated by data fitting and both models were able to accurately describe the evolution of the system, in terms of reactants and product distribution as a function of time under the experimental conditions studied.
- Jaworski, María A.,Rodríguez Vega, Sergio,Siri, Guillermo J.,Casella, Mónica L.,Romero Salvador, Arturo,Santos López, Aurora
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- Synthesis of unsaturated phosphatidylinositol 4-phosphates and the effects of substrate unsaturation on SopB phosphatase activity
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In this paper evidence is presented that the fatty acid component of an inositide substrate affects the kinetic parameters of the lipid phosphatase Salmonella Outer Protein B (SopB). A succinct route was used to prepare the naturally occurring enantiomer of phosphatidylinositol 4-phosphate (PI-4-P) with saturated, as well as singly, triply and quadruply unsaturated, fatty acid esters, in four stages: (1) The enantiomers of 2,3:5,6-O-dicyclohexylidene-myo-inositol were resolved by crystallisation of their di(acetylmandelate) diastereoisomers. (2) The resulting diol was phosphorylated regio-selectively exclusively on the 1-O using the new reagent tri(2-cyanoethyl)phosphite. (3) With the 4-OH still unprotected, the glyceride was coupled using phosphate tri-ester methodology. (4) A final phosphorylation of the 4-O, followed by global deprotection under basic then acidic conditions, provided PI-4-P bearing a range of sn-1-stearoyl, sn-2-stearoyl, -oleoyl, -γ-linolenoyl and arachidonoyl, glycerides. Enzymological studies showed that the introduction of cis-unsaturated bonds has a measurable influence on the activity (relative Vmax) of SopB. Mono-unsaturated PI-4-P exhibited a five-fold higher activity, with a two-fold higher KM, over the saturated substrate, when presented in DOPC vesicles. Poly-unsaturated PI-4-P showed little further change with respect to the singly unsaturated species. This result, coupled with our previous report that saturated PI-4-P has much higher stored curvature elastic stress than PI, supports the hypothesis that the activity of inositide phosphatase SopB has a physical role in vivo. This journal is
- Furse, Samuel,Mak, Lokhang,Tate, Edward W.,Templer, Richard H.,Ces, Oscar,Woscholski, Rüdiger,Gaffney, Piers R. J.
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p. 2001 - 2011
(2015/03/05)
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- Selective functionalization of the primary hydroxy group in triols
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A procedure was suggested for preparing functionally substituted 1,2-diols by O-alkylation of hydroxyalkyl-1,3-dioxacyclanes with alkyl halides, followed by acid hydrolysis. The conditions for selective cleavage of the ethers obtained were found. (2,2-Dimethyl-1,3-dioxolan-4-yl)methyl benzoate under the conditions of acid deacetalization undergoes saponification of the ester group.
- Raskil'Dina,Valiev,Sultanova,Zlotskii
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p. 1599 - 1604
(2016/02/18)
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- Supramolecular assemblies of novel aminonucleoside phospholipids and their bonding to nucleic acids
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A novel class of aminonucleoside phospholipids has been developed. These molecules could spontaneously assemble into supramolecular structures including multilamellar organization, hydrogels, superhelical strands, and vesicles. Their ability to bind to DNA by hydrogen bonding and π-π stacking interactions was investigated by many means. This journal is
- Pan, Delin,Sun, Jing,Jin, Hongwei,Li, Yating,Li, Liyu,Wu, Yun,Zhang, Lihe,Yang, Zhenjun
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supporting information
p. 469 - 472
(2015/02/19)
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- The role of mesoporosity and Si/Al ratio in the catalytic etherification of glycerol with benzyl alcohol using ZSM-5 zeolites
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A comparative study of the influence of three different acid solids as catalysts (conventional zeolites Z15c with Si/Al = 19.5 and Z40c with Si/Al = 48.2, and a hierarchical zeolite Z40c-H with Si/Al = 50.0) for the etherification of glycerol with benzyl alcohol was performed. The catalytic activity and selectivity of these zeolites was elucidated at different catalyst contents. Three different ethers (3-benzyloxy-1,2-propanediol, which is a mono-benzyl-glycerol ether (MBG) and 1,3-dibenzyloxy-2-propanol, which is a di-benzyl-glycerol ether (DBG) and dibenzyl ether (DBz) were identified as the main products. MBG was the major product of the reaction catalyzed by the microporous Z15c zeolite with low Si/Al molar ratio, whereas DBG was formed in higher yield with the use of microporous Z40c and hierarchical Z40c-H zeolites, both of them having a similar high Si/Al molar ratio (≈50 MBG is a value-added product andit is obtained with good yield and selectivity when using the conventional zeolite Z15c as a catalyst.Under the best conditions tested, i.e., 25 mg of catalyst for 8 h at 120°C, a 62% of conversion was obtainedwithout the need of solvent, with an excellent 84% selectivity toward the MBG and no formation of DBz.
- Gonzalez-Arellano, Camino,Grau-Atienza, Aida,Serrano, Elena,Romero, Antonio A.,Garcia-Martinez, Javier,Luque, Rafael
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- ANTIBACTERIAL AGENTS
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Antibacterial compounds of formula (I) are provided, as well as stereoisomers and pharmaceutically acceptable salts thereof; pharmaceutical compositions comprising such compounds; methods of treating bacterial infections by the administration of such compounds; and processes for the preparation of such compounds.
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- Acyclic nucleoside phosphonates containing a second phosphonate group are potent inhibitors of 6-oxopurine phosphoribosyltransferases and have antimalarial activity
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Acyclic nucleoside phosphonates (ANPs) that contain a 6-oxopurine base are good inhibitors of the Plasmodium falciparum (Pf) and Plasmodium vivax (Pv) 6-oxopurine phosphoribosyltransferases (PRTs). Chemical modifications based on the crystal structure of 2-(phosphonoethoxy)ethylguanine (PEEG) in complex with human HGPRT have led to the design of new ANPs. These novel compounds contain a second phosphonate group attached to the ANP scaffold. {[(2-[(Guanine-9H-yl) methyl]propane-1,3-diyl)bis(oxy)]bis(methylene)}diphosphonic acid (compound 17) exhibited a Ki value of 30 nM for human HGPRT and 70 nM for Pf HGXPRT. The crystal structure of this compound in complex with human HGPRT shows that it fills or partially fills three critical locations in the active site: the binding sites of the purine base, the 5′-phosphate group, and pyrophosphate. This is the first HG(X)PRT inhibitor that has been able to achieve this result. Prodrugs have been synthesized resulting in IC50 values as low as 3.8 μM for Pf grown in cell culture, up to 25-fold lower compared to the parent compounds.
- Keough, Dianne T.,?pa?ek, Petr,Hocková, Dana,Tichy, Tomá?,Vrbková, Silvie,Slavětínská, Lenka,Janeba, Zlatko,Naesens, Lieve,Edstein, Michael D.,Chavchich, Marina,Wang, Tzu-Hsuan,De Jersey, John,Guddat, Luke W.
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p. 2513 - 2526
(2013/05/22)
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- Catalytic hydrogenation of cyclic carbonates: A practical approach from CO2 and epoxides to methanol and diols
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As an economical, safe and renewable carbon resource, CO2 turns out to be an attractive C1 building block for making organic chemicals, materials, and carbohydrates.[1] From the viewpoint of synthetic chemistry,[2] the utilization of CO2 as a feedstock for the production of industrial products may be an option for the recycling of carbon.[3] On the other hand, the transformation of chemically stable CO2 represents a grand challenge in exploring new concepts and opportunities for the academic and industrial development of catalytic processes.[4] The catalytic hydrogenation of CO2 to produce liquid fuels such as formic acid (HCO 2H)[5] or methanol[6] is a promising solution to emerging global energy problems. Methanol, in particular, is not only one of the most versatile and popular chemical commodities in the world, with an estimated global demand of around 48 million metric tons in 2010, but is also considered as the key to weaning the world off oil in the future.[6e, f] Although the production of methanol has already been industrialized by the hydrogenation of CO with a copper/zinc-based heterogeneous catalyst at high temperatures (250-300°C) and high pressures (50-100 atm),[6e, 7] the development of a practical catalytic system for the hydrogenation of CO2 into methanol still remains a challenge, as high activation energy barriers have to be overcome for the cleavage of the C=O bonds of CO2, albeit with favorable thermodynamics.[8] Heterogeneous catalysis for the hydrogenation of CO 2 into CH3OH has been extensively investigated, and Cu/Zn-based multi-component catalyst was found to be highly selective with a long life, but under relatively harsh reaction conditions (250 °C, 50 atm).[3b, 6d] Therefore, the production of methanol from CO2 by direct hydrogenation under mild conditions is still a great challenge for both academia and industry.
- Han, Zhaobin,Rong, Liangce,Wu, Jiang,Zhang, Lei,Wang, Zheng,Ding, Kuiling
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supporting information
p. 13041 - 13045
(2013/03/13)
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- Environmentally benign metal triflate-catalyzed reductive cleavage of the C-O bond of acetals to ethers
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A protocol is described for the reductive cleavage of the C-O bond of aromatic and aliphatic acetals to ethers catalyzed by Cu(OTf)2 or Bi(OTf)3 at room temperature in excellent yields, without affecting aromatic rings, nitro, nitrile, ester and hydroxyl groups. This protocol represents an improvement in terms of atom economy compared to the previous methods, by distinctly decreasing the amount of the reducing reagent, 1,1,3,3-tetramethyldisiloxane (TMDS), and using a small amount of catalyst.
- Zhang, Yin-Jie,Dayoub, Wissam,Chen, Guo-Rong,Lemaire, Marc
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experimental part
p. 2737 - 2742
(2011/11/29)
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- TMDS-Pd/C: A convenient system for the reduction of acetals to ethers
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A simple and practical procedure for the reduction of acetals to ethers is described. It is based on the use of a 1,1,3,3-tetramethyldisiloxane (TMDS)-Pd/C system in the presence of a Br?nsted acid as the co-catalyst. The reaction occurs under mild conditions and ethers are obtained in high yields.
- Shi, Yan,Dayoub, Wissam,Chen, Guo-Rong,Lemaire, Marc
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experimental part
p. 1281 - 1283
(2011/03/22)
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- An unusual (R)-selective epoxide hydrolase with high activity for facile preparation of enantiopure glycidyl ethers
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A novel epoxide hydrolase (BMEH) with unusual (R)-enantioselectivity and very high activity was cloned from Bacillus megaterium ECU1001. Highest enantioselectivities (E>200) were achieved in the bioresolution of ortho-substituted phenyl glycidyl ethers and para-nitrostyrene oxide. Worthy of note is that the substrate structure remarkably affected the enantioselectivities of the enzyme, as a reversed (S)-enantiopreference was unexpectedly observed for the ortho-nitrophenyl glycidyl ether. As a proof-of-concept, five enantiopure epoxides (>99% ee) were obtained in high yields, and a gram-scale preparation of (S)-ortho-methylphenyl glycidyl ether was then successfully performed within a few hours, indicating that BMEH is an attractive biocatalyst for the efficient preparation of optically active epoxides. Copyright
- Zhao, Jing,Chu, Yan-Yan,Li, Ai-Tao,Ju, Xin,Kong, Xu-Dong,Pan, Jiang,Tang, Yun,Xu, Jian-He
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experimental part
p. 1510 - 1518
(2011/08/03)
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- BORON-CONTAINING SMALL MOLECULES
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Compounds, pharmaceutical formulations, and methods of treating anti-inflammatory conditions and/or helminth-associated diseases are disclosed.
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- Intramolecular reductive amination strategy to the synthesis of (R)-N-Boc-2-hydroxymethylmorpholine, N-(3,4-dichlorobenzyl)(R)-2-hydroxymethylmorpholine, and (R)-2-benzylmorpholine
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A concise high yielding enantioselective synthesis of (R)-N-Boc-2-hydroxymethylmorpholine, N-(3,4-dichlorobenzyl)(R)-2-hydroxymethylmorpholine, and (R)-benzylmorpholine has been achieved by employing proline-catalyzed asymmetric α-aminooxylation of aldehyde and palladium-catalyzed intramolecular reductive amination of azido aldehyde as the key steps.
- Sawant, Rajiv T.,Waghmode, Suresh B.
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experimental part
p. 2010 - 2014
(2010/04/26)
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- AN IMPROVED PROCESS FOR PREPARING PURINE DERIVATIVE
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A process for the preparation of famciclovir a compound of Formula (I) and its intermediates.
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Page/Page column 11
(2009/01/23)
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- Preparation of optically active 1-O-alkyl-3-O-arylsulfonyl-sn-grycerol derivatives: Substrate engineering in enzyme-mediated enantioselective hydrolysis
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Lipase PS catalyzes the enantioselective hydrolysis of various 2-acetyl compounds of the 1-O-alkyl-3-O-arylsulfonyl-sn-glycerol derivatives to afford the corresponding optically active compounds. Changing the structure of the 1-O-alkyl and 3-O-arylsulfonyl groups affects both the reactivity and enantioselectivity. Finally, the E value of the reaction for 2-acetyl-3-O-3,5-dimethylbenzenesulfonyl-1-O-4-methoxybenzyl-sn-glycerol is greater than 200. Georg Thieme Verlag Stuttgart.
- Shimada, Yasutaka,Sato, Hiroshi,Mochizuki, Sachiyo,Matsumoto, Kazutsugu
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experimental part
p. 2981 - 2984
(2009/10/17)
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- Ce(IV) ammonium nitrate catalyzed chemoselective deprotection of acetonides
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Highly chemoselective deprotection of diacetone sugars have been achieved at room temperature in excellent yields using commercially available eerie ammonium nitrate (20 mol%) in moist CH3CN.
- Jana,Roy
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p. 707 - 709
(2008/09/18)
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- Intermolecular reactions of chlorohydrine anions: Acetalization of carbonyl compounds under basic conditions
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Nonenolizable aldehydes and ketones react with 2-chloroethanol and 3-chloropropanol under basic conditions (t-BuOK, DMF/THF) with formation of 2-substituted 1,3-dioxolanes and 1,3-dioxanes, respectively. Conversion of the two-step addition-alkylation process depends on the electrophilicity of the carbonyl group that governs the equilibrium of addition of chloroalkoxides. This method of protection of carbonyl groups in the form of cyclic acetals under kinetically controlled conditions is complementary to the acid-catalyzed reaction with diols.
- Barbasiewicz, Michal,Makosza, Mieczyslaw
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p. 3745 - 3748
(2007/10/03)
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- Lipid-improving agent and composition containing lipid-improving agent
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A lipid-improving agent containing a triglyceride(s) where a poly-unsaturated fatty acid is bonded to 2-position of a triglyceride(s).
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Page/Page column 7
(2010/11/23)
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- METHOD FOR PRODUCING HEXAHYDROFUROFURANOL DERIVATIVE
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Disclosed is a method for producing a compound (IV) which comprises a step for obtaining a compound (III) by reacting a compound (I) with a compound (II) in the presence of an optionally substituted cyclic secondary amine, and a step for obtaining the compound (IV) by removing R1 and R2 from the compound (III) sequentially or at a time and then cyclizing the compound from which the R1 and R2 are removed. Also disclosed is a method for producing a high-purity compound (IV), an intermediate thereof, and a method for producing the intermediate.
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Page/Page column 29
(2008/06/13)
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- Regio- and stereoselectivity in preparation of 2-deoxysugar glycoglycerolipid derivatives evaluated by high resolution 1H NMR
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New glycoglycerolipids, derivatives of 2-deoxysugars bearing one or two fatty acid chains have been synthesised. Various levels of regio- and stereoselectivity have been attained for the triphenylphosphine hydrobromide (TPHB) catalysed addition of the glycerol moiety to some representative glycals. The influence of the structure of glycal derivatives in glycosylation reactions is discussed.
- Wandzik, Ilona,Bugla, Joanna,Szeja, Wieslaw
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- Mild, efficient, and selective cleavage of trityl ethers with antimony trichloride
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Selective detritylation is quite crucial in synthetic chemistry. A mild and efficient procedure for selective hydrolysis of trityl ethers in the presence of other frequently used hydroxy protecting groups: TBDPS, Bz, Bn, Ac and Ts with antimony trichloride was described and 5′-trityl uridine was detritylated smoothly too. Copyright Taylor & Francis Group, LLC.
- Wu, Qinpei,Wang, Yuan,Chen, Wei,Liu, Hua
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p. 1361 - 1366
(2007/10/03)
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- Preparation of homoallylic homopropargylic alcohols from 2-vinyloxiranes
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(Chemical Equation Presented) β,γ-Unsaturated aldehydes generated in situ by treatment of 2-vinyloxiranes with a catalytic amount of Sc(OTf)3 or BF·OEt2 are effectively trapped by B-allenyl-9-BBN to afford homoallylic homopropargylic alcohols in high yield. An enantioselective version has been demonstrated, and a convenient synthesis of 9-allenyl-9-BBN is described.
- Maddess, Matthew L.,Lautens, Mark
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p. 3557 - 3560
(2007/10/03)
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- Modified bio-related substance, process for producing the same, and intermediate
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A modified bio-related substance, wherein at least one poly(alkylene glycol)oxy group represented by the following formula (1) is combined in a molecule: wherein R is a hydrocarbon group having 1 to 24 carbon atoms, OA1 and OA2 are each an oxyalkylene group having 2 to 4 carbon atoms, R and OA2 are the same or different from each other in one molecule, n and m are each average number of moles of the oxyalkylene group added, n represents 0 to 1000, and m represents 10 to 1000.
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Page/Page column 18; 26
(2008/06/13)
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- Modified bio-related substance, process for producing the same, and intermediate
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A modified bio-related substance, wherein at least one poly(alkylene glycol)oxy group represented by the following formula (1) is combined in a molecule: wherein R is a hydrocarbon group having 1 to 24 carbon atoms, OA1 and OA2 are each an oxyalkylene group having 2 to 4 carbon atoms, the groups represented by R are the same or different from each other in one molecule, and the groups represented by OA2 are the same or different from each other in one molecule, n and m are each average number of moles of the oxyalkylene group added, n represents 0 to 1000, and m represents 10 to 1000.
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- A highly efficient synthesis of the C-13 side-chain of taxol using Shibasaki's asymmetric Henry reaction
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The synthesis of the C-13 side-chain of taxol has been achieved using Shibasaki's asymmetric Henry reaction catalyzed by an optically active rare earth lanthanum-(R)-binaphthol complex.
- Borah, Jagat C.,Gogoi, Siddhartha,Boruwa, Joshodeep,Kalita, Biswajit,Barua, Nabin C.
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p. 3689 - 3691
(2007/10/03)
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