109-06-8Relevant articles and documents
(Oligo)mannose functionalized hydroxyethyl starch nanocapsules: En route to drug delivery systems with targeting properties
Freichels, Helene,Wagner, Manfred,Okwieka, Patricia,Meyer, Ralf Georg,Mailaender, Volker,Landfester, Katharina,Musyanovych, Anna
, p. 4338 - 4348 (2013)
Hydroxyethyl starch nanocapsules (NCs) are potentially interesting hydrophilic drug delivery carriers, since they do not show non-specific interactions with the living cells. Only the presence of a targeting agent on their surface allows them to target specifically the desired site of action. In this paper, we report the synthesis and cell uptake of crosslinked hydroxyethyl starch (HES) NCs decorated with (oligo)mannose, which is an effective targeting agent for macrophage and dendritic cells. The crosslinked HES NCs were prepared via the interfacial polyaddition of HES with 2,4-toluene diisocyanate (TDI) in inverse (water-in-oil) miniemulsion and then functionalized with (oligo)mannose following two different strategies. To compare the activity and availability of a targeting agent, different types of mannose molecules such as α-d-mannopyranosylphenyl isothiocyanate, 3-O-(α-d-mannopyranosyl)-d- mannose and α3,α6-mannotriose were used for the functionalization of NCs. The availability of the mannose was unambiguously assessed by interaction with a fluorescent lectin. Moreover, the accessibility of the pilot molecule was improved by the presence of a PEG linker at the surface of the NCs. To simulate in vivo conditions, where proteins interact with nanoparticles with a possible hindrance of the accessibility to the targeting agent, the mannosylated NCs were first incubated with human serum before interaction with the fluorescent lectin. Enhancement of uptake into dendritic cells demonstrates the targeting ability in in vitro studies. The Royal Society of Chemistry 2013.
REACTIVITY OF ISOMERIC PYRIDINECARBOXALDEHYDES IN CATALYTIC HYDROGENATION
Yansone, D. P.,Stonkus, V. V.,Leitis, La. Ya.,Fleisher, M. B.,Shimanska, M.
, p. 934 - 937 (1994)
It has been established by a quantum-chemical method (CNDO/2) that there are two possible mechanisms occuring in the vapor-phase hydrogenation of 2-, 3- and 4-pyridinecarboxaldehydes in the presence of a copper-chromium catalyst at 180-300 deg C.One of these involves a donor-acceptor interaction of aldehyde with catalyst and the addition of hydrogen to the carbon atom of the carbonyl group at the first stage.The second possible mechanism is the synchronous addition of hydrogen to the carbon and oxygen of the carbonyl group of a weakly bound a aldehyde molecule with an unchanged electronic structure.
Direct Phosphonation of Quinolinones and Coumarins Driven by the Photochemical Activity of Substrates and Products
Kim, Inwon,Min, Minsik,Kang, Dahye,Kim, Kiho,Hong, Sungwoo
, p. 1394 - 1397 (2017)
Light-promoted phosphonation of quinolinones and coumarins was developed without the need for an external photocatalyst. Investigations support a mechanism whereby both starting materials and products act as photosensitizers upon excitation using compact fluorescent light sources to photochemically promote the dissociation of the N-O bond in the pyridinium salt by a single electron transfer pathway. A wide range of quinolinone and coumarin substrates can be utilized in the phosphonation process under mild reaction conditions.
Preparation of 2-picolylarsonic acid and its reductive cleavage by ascorbic acid/iodine and by thiophenol
Ioannou, Panayiotis V.,Afroudakis, Pantelis A.,Siskos, Michael G.
, p. 2773 - 2783 (2002)
Contrary to dialkylaminoethyl halides, 2-picolyl chloride reacts with alkaline arsenite to give nearly quantitative yields 2-picolylarsonic acid. This acid is decomposed by ascorbic acid in the presence of catalytic amounts of iodine to 2-picoline and arsenious acid, most likely by hydride transfer from the ascorbic acid. Thiophenol decomposes this arsonic acid very quickly to 2-picoline, diphenyl disulfide and triphenyl trithioarsenite. In this case a proton from the thiophenol is transferred to the incipient 2-picolyl carbanion.
Anti-Markovnikov Hydroarylation of Unactivated Olefins via Pyridyl Radical Intermediates
Boyington, Allyson J.,Riu, Martin-Louis Y.,Jui, Nathan T.
, p. 6582 - 6585 (2017)
The intermolecular alkylation of pyridine units with simple alkenes has been achieved via a photoredox radical mechanism. This process occurs with complete regiocontrol, where single-electron reduction of halogenated pyridines regiospecifically yields the corresponding radicals in a programmed fashion, and radical addition to alkene substrates occurs with exclusive anti-Markovnikov selectivity. This system is mild, tolerant of many functional groups, and effective for the preparation of a wide range of complex alkylpyridines.
Coordination Chemistry of Borane in Solution: Application to a STING Agonist
Lemaire, Sébastien,Zhdanko, Alexander,van der Worp, Boris A.
, (2022/04/09)
Equilibrium constants were determined for ligand exchange reactions of borane complexes with various oxygen, sulfur, nitrogen, and phosphorus nucleophiles in solution, and a binding affinity scale was built spanning a range of 12 orders of magnitude. While the Keq are minimally dependent on the solvent, the rate of ligand exchange varies significantly. The fastest and slowest rates were observed in THF and CDCl3, respectively. Moreover, the ligand exchange rate differs in a very broad range depending on stability of the starting complex. Binding of BH3 was found to be much more sensitive to steric factors than protonation. Comparing nitrogen bases having equal steric properties, a linear correlation of BH3 binding affinity vs. Br?nsted acidity was found. This correlation can be used to quickly estimate the BH3 binding affinity of a substrate if pKa is known. Kinetic studies suggest the ligand exchange to occur as a bimolecular SN2 reaction unless other nucleophilic species were present in the reaction mixture.
Synthesis and characterization of a well-defined carbon nanohorn- supported molybdenum dioxo catalyst by SMART-EM imaging. surface structure at the atomic level
Kratish, Yosi,Nakamuro, Takayuki,Liu, Yiqi,Li, Jiaqi,Tomotsuka, Issei,Harano, Koji,Nakamura, Eiichi,Marks, Tobin J.
supporting information, p. 427 - 432 (2021/03/15)
The molybdenum dioxo catalyst CNH/MoO2 is prepared via direct grafting of (dme)MoO2Cl2 (dme = 1,2-dimethoxyethane) onto the graphitic surfaces of carbon nanohorn (CNH) substrates. The structure of this heterogeneous catalyst was characterized by SMART-EM, XPS, and ICP, and is found to have single isolated MoO2 species on the surface as well as a few multi-Mo species. The CNH/MoO2 complex exhibits excellent catalytic activity for polyethylene terephthalate (PET) hydrogenolysis, N-oxide reductions, and reductive carbonyl coupling, representing an informative model catalyst for structural and mechanistic investigations.
Clean protocol for deoxygenation of epoxides to alkenes: Via catalytic hydrogenation using gold
Fiorio, Jhonatan L.,Rossi, Liane M.
, p. 312 - 318 (2021/01/29)
The epoxidation of olefin as a strategy to protect carbon-carbon double bonds is a well-known procedure in organic synthesis, however the reverse reaction, deprotection/deoxygenation of epoxides is much less developed, despite its potential utility for the synthesis of substituted olefins. Here, we disclose a clean protocol for the selective deprotection of epoxides, by combining commercially available organophosphorus ligands and gold nanoparticles (Au NP). Besides being successfully applied in the deoxygenation of epoxides, the discovered catalytic system also enables the selective reduction N-oxides and sulfoxides using molecular hydrogen as reductant. The Au NP catalyst combined with triethylphosphite P(OEt)3 is remarkably more reactive than solely Au NPs. The method is not only a complementary Au-catalyzed reductive reaction under mild conditions, but also an effective procedure for selective reductions of a wide range of valuable molecules that would be either synthetically inconvenient or even difficult to access by alternative synthetic protocols or by using classical transition metal catalysts. This journal is
Microporous and Micro-meso-macroporous Y Zeolites in the Synthesis of 2-Methyl-5-ethylpyridine
Grigor’eva,Filippova,Bubennov,Khazipova,Kutepov,Dyakonov
, p. 364 - 369 (2021/03/19)
Abstract: The study investigates the catalytic properties of microporous (H–Y) andmicro-meso-macroporous (H–Y-mmm) FAU-type zeolites in the synthesis of2-methyl-5-ethylpyridine (MEP) by the reaction of acetaldehyde with ammonia. At150°C, an acetaldehyde to ammonia molar ratio of 1 : 3, and a catalyst contentof 10 wt %, a MEP yield of 58% (0.95H–Y) and 63% (0.95H–Y-mmm) was achieved witha MEP selectivity of 91 and 93%, respectively. The examination of the catalyststability revealed that hierarchical H–Y-mmm zeolites ensure a 100% MEPselectivity during 4–5 cycles with a slight decline in the catalytic activity,while H–Y zeolites are active during the first cycle only.
Metal-Organic Framework-Confined Single-Site Base-Metal Catalyst for Chemoselective Hydrodeoxygenation of Carbonyls and Alcohols
Antil, Neha,Kumar, Ajay,Akhtar, Naved,Newar, Rajashree,Begum, Wahida,Manna, Kuntal
supporting information, p. 9029 - 9039 (2021/06/28)
Chemoselective deoxygenation of carbonyls and alcohols using hydrogen by heterogeneous base-metal catalysts is crucial for the sustainable production of fine chemicals and biofuels. We report an aluminum metal-organic framework (DUT-5) node support cobalt(II) hydride, which is a highly chemoselective and recyclable heterogeneous catalyst for deoxygenation of a range of aromatic and aliphatic ketones, aldehydes, and primary and secondary alcohols, including biomass-derived substrates under 1 bar H2. The single-site cobalt catalyst (DUT-5-CoH) was easily prepared by postsynthetic metalation of the secondary building units (SBUs) of DUT-5 with CoCl2 followed by the reaction of NaEt3BH. X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy (XANES) indicated the presence of CoII and AlIII centers in DUT-5-CoH and DUT-5-Co after catalysis. The coordination environment of the cobalt center of DUT-5-Co before and after catalysis was established by extended X-ray fine structure spectroscopy (EXAFS) and density functional theory. The kinetic and computational data suggest reversible carbonyl coordination to cobalt preceding the turnover-limiting step, which involves 1,2-insertion of the coordinated carbonyl into the cobalt-hydride bond. The unique coordination environment of the cobalt ion ligated by oxo-nodes within the porous framework and the rate independency on the pressure of H2 allow the deoxygenation reactions chemoselectively under ambient hydrogen pressure.
