查看更多>>摘要：Micellar catalysis is having a dramatic impact in improving the sustainability of a wide variety of chemical transformations, including most of the popular palladium mediated carbon-carbon and carbon-nitrogen bond forming reactions. The Suzuki-Miyaura coupling is one of the earliest examples of micellar catalyzed reactions and it is still a very much active research field even at industrial scale. So far, micellar catalysis proved particularly efficient in enabling the high yield, low catalyst loading and mild reaction condition coupling of hydrophobic reagents in a water solution of selected surfactants. In this paper we show that the use of aqueous solutions of a mixture of food grade lecithin and the industrial surfactant Tween 80 not only enables efficient coupling in water of hydrophobic chemicals, but also provides a very resourceful tool for the functionalization of water and organic solvent insoluble pigments of interest for the dye and printed electronic industries. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Interesting organic-inorganic copper-based nanostructures corresponding to [cation](+)[CunCln+1]- were successfully prepared by reacting chlorinate ionic liquids containing a coordinating center with CuCl. The value of "n" in anionic part [CunCln+1](-) was observed to be dependent on the properties of the cation in the used ionic liquids with which co-precipitation occurs. The ionic liquids containig functional groups such as N-sites or OH functions, which can form coordination and electrostatic interactions towards chlorocuprates(I), affect the coordination environment of copper species and the particle size in the generated structures. All resulted microscopic data of [choline](+)[CuCl2](-), [N-benzyl DABCO](+)[Cu4Cl5](-), [N-benzyl nicotine](+)[Cu4Cl5](-) and [choline]+[Cu3Cl4](-) showed the formation of nano-meter particles in the matrix of these materials. The new chlorocuprate(I) derived from choline chloride [choline](+)[Cu3Cl4](-) was well characterized by elemental analysis, FESEM, TEM, ICP and mass spectrometry (MS) and was found to be efficient in the Sonogashira C-C cross-coupling reactions and the one-pot synthesis of quinazolin-4(1H)-one derivatives via multicomponent reaction of isatoic anhydride, aldehyde and aromatic amines. (C) 2022 Elsevier B.V. All rights reserved.
Boganov, Sergey E.Becerra, RosaPromyslov, Vladimir M.Shangin, Pavel G....
14页
查看更多>>摘要：A matrix-isolation FTIR study of the reaction between SiCl2 and acetylene showed that at low temperatures, it stops at the stage of complexation between the reactants. This made it possible to examine a photochemical version of this reaction, which led to the simultaneous formation of 1,1-dichloro-1-silacycloprop-2-ene and 3,3-dichloro-3-silaprop-1-yne in comparable yields in contrast to the thermal reaction, which, according to quantum chemical calculations carried out here, results in the formation of 1,1-dichloro-1-silacycloprop-2-ene as the only primary product. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Six cationic half-sandwich Ir(III) and Rh(III) complexes (C1-C6) were synthesised by reaction of 2-(2-pyridyl)benzimidazole with the appropriate chloro-bridged dimers. All complexes were fully characterised using standard spectroscopic techniques and their purity confirmed by RP-HPLC. The molecular structures of these complexes were elucidated using single-crystal X-ray diffraction. Depending on the substituted cyclopentadienyl (Cp-x) ligands, the complexes crystallized with an orthorhombic (Cp-x = pentamethylcy-clopentadienyl), monoclinic (Cp-x = tetramethylphenylcyclopentadienyl) or triclinic (Cp-x = tetramethyl-biphenylcyclopentadienyl) crystal system. All complexes displayed good solubility in PBS and HEPES buffers within the concentration range used for the in vitro inhibitory screening. Using proton NMR experiments, the stability of the complexes in water was monitored at 37 degrees C and all complexes were resistant to displacement of their chlorido ancillary ligands by water. In vitro screening against the 3D7 chloroquine-sensitive and Dd2 multi-drug-resistant strains of Plasmodium falciparum revealed all complexes exhibited moderate to good potency. Complex C6 emerged as the most promising candidate with IC50 values of 0.75 +/- 0.11 and 0.42 +/- 0.055 mu M against the 3D7 and Dd2 strains, respectively. The newly synthesised complexes were not cytotoxic to Human Embryonic Kidney cells. (C) 2022 Elsevier B.V. All rights reserved.
Thavornpradit, SopidaMalinski, Thomas J.Bergbreiter, David E.
10页
查看更多>>摘要：Poly(alpha-olefin)s (PAOs) that can be used as alternative solvents and solvent systems for catalysis and synthesis can substitute for conventional alkane solvents like pentane, hexane, and heptane for storage and in reactions of reactive organometallics. In this work, we show that organolithium reagents including polymer-supported diphenyllithium and triaryllithium reagents have extended stability as suspensions or as solutions in PAOs just as is the case for alkyllithium reagents. These highly colored species are stable in PAO solvents for months. PAOs can also be used as safer solvents for dialkylmagnesium reagents. In PAO solvents, these dialkylmagnesium reagents behave in reactions with electrophiles like benzaldehyde, benzophenone, and carbon dioxide the same as they do in heptane. PAOs can also be used as recyclable solvents in hydroboration/oxidation of alkenes when products are separated from the PAO by distillation or extraction. In contrast to PAO solutions of alkyllithium or dialkylmagnesium reagents, the PAO in a solution of trihexylborane in PAO did not itself inflame on exposure to a propane torch flame. While the alkylborane did burn briefly with a green flame, that flame due to the borane self-extinguishes after the borane is consumed. The PAO does not itself catch fire. Finally, we examined the recyclability and reactivity of PAO solvents containing a polyisobutylene (PIB) bound analog of LDA in enolate chemistry. Our results show that lithium PIB-tert-butylamide in PAO behaves like LDA or PIB-tert-butylamide in THE or heptane in formation of trimethylsilyl enol ethers from ketones with the difference being that PIB-tert-butylamide in a PAO solution is a fully recyclable reagent/solvent system. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：It was found that anionic Pd(II) complexes of type [CA](2)[PdCl4] and [CA](2)[Pd2Cl6] (CA = imidazolium or pyridinium cation) are effective catalysts for copper-free Sonogashira coupling in an aqueous medium without additional ligands or co-catalysts. Both types of substrates, containing electron donor or electron acceptor groups, formed the corresponding products in good to excellent yield. The most active complex, [bmpy](2)[Pd2Cl6] (bmpy = 1-butyl-4-methylpyridinium cation), was employed to the hydroarylation of the Sonogashira product in a one-pot process, using microwave radiation, NaBPh4 as a phenyl source and water as a proton donor. In these reactions the presence of electron donor substituents facilitated a higher conversion of diarylacetylenes to triarylethenes than electron acceptor groups. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The biologically relevant arenes ethyl salicylate and salicylic amide as well as the fluorescent coumarin and pyrene units were functionalized with a cyclopentadiene unit. The Re and Tc-99m complexes of the latter two were synthesized and fully characterized. During crystallization of the ligands, [2+2] and [6+6] cycloadditions were observed for the cyclopentadiene modified coumarin. A light-induced mechanism, supported by DFT calculations, is proposed for these reactions. The fluorescent properties of the coumarin and pyrene based cyclopentadienes and their corresponding Re complexes were investigated. (C) 2022 The Authors. Published by Elsevier B.V.
Stein, AlinaLiang, Alexandria DelizSahin, ReyhanWard, Thomas R....
6页
查看更多>>摘要：The potential of artificial metalloenzymes has led to an increase in interest for the design of novel metal-binding sites in proteins. Metal-chelating unnatural amino acids offer an auspicious solution to engineer active metal sites in a defined way. Herein, we describe the introduction of four metal-chelating unnatural amino acids into HaloTag, an attractive scaffold for the assembly of functional artificial metalloenzymes. HaloTag, engineered with 2-amino-3-(8-hydroxyquinolin-5-yl)propanoic acid (HQ-Ala-1) was used to assemble an artificial metalloenzyme for improved allylic deamination upon complementation with [(eta(5)-C5H5)Ru(MeCN)(3)](+). (C) 2022 The Authors. Published by Elsevier B.V.
Carter, Carly C.Cundari, Thomas R.Rodriguez, George
8页
查看更多>>摘要：In the present quantum chemical study, alpha-olefin dimerization and trimerization by zirconium boratabenzene catalysts has been studied as the single-site reactivity of group 4 metallocene catalysts has proven to be industrially important. The thermodynamics and kinetics of C = C insertion for ethylene, 1-butene, and 1-hexene as well as relevant ss-H elimination barriers have been quantified using density functional theory, using methodology previously calibrated in earlier research by the University of North Texas (UNT) and the ExxonMobil Chemical Company (EMCC) team for bis-indenyl zirconium catalysts. The insertions of the alkenes are relevant to chain growth processes, while the ss-H eliminations model chain termination. Various substituents on the boratabenzene rings were also compared to determine how these ligands change the thermodynamics and kinetics of the insertion and chain termination steps. (c) 2022 Elsevier B.V. All rights reserved.
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