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105-39-5Relevant articles and documents
Enhanced Electrophilicity of Heterobimetallic Bi-Rh Paddlewheel Carbene Complexes: A Combined Experimental, Spectroscopic, and Computational Study
Collins, Lee R.,Van Gastel, Maurice,Neese, Frank,Fürstner, Alois
, p. 13042 - 13055 (2018)
Dirhodium paddlewheel complexes are indispensable tools in modern organometallic catalysis for the controlled decomposition of diazo-compounds. Tuning the reactivity of the thus-formed transient carbenes remains an active and dynamic field of research. Herein, we present our findings that the distal metal center plays an as yet underappreciated role in modulating this reactivity. Replacement of one rhodium atom in the bimetallic core for bismuth results in the formation of a significantly more electrophilic carbene complex. Bismuth-rhodium catalysts thereby facilitate previously unknown modes of reactivity for α-diazoester compounds, including the cyclopropanation of alkenes as electron deficient as trichloroethylene. While dirhodium paddlewheel complexes remain the catalysts of choice for many carbene-mediated transformations, their bismuth-rhodium analogues exhibit complementary reactivity and show great potential for small molecule and solvent activation chemistry. DFT calculations highlight the importance of metal-metal bonding interactions in controlling carbene electrophilicity. The paucity of these interactions between the 4d orbitals of rhodium and the 6p orbitals of bismuth results in weaker π-back-bonding interactions for bismuth-rhodium carbene complexes compared to dirhodium carbene complexes. This leads to weakening of the rhodium-carbene bond and to a more carbene-centered LUMO, accounting for the observed enhancement in bismuth-rhodium carbene electrophilicity. These findings are supported by a detailed spectroscopic study of the "donor-donor" carbene complexes Rh2(esp)2C(p-MeOPh)2 (19) and BiRh(esp)2C(p-MeOPh)2 (20), employing a combination of UV-vis and resonance Raman spectroscopy. The results reveal that carbene chemoselectivity in MRh(L)4 catalysis can be modulated to a previously unrecognized extent by the distal metalloligand.
Microwave synthesis of chloroacetic acid with acetic anhydride catalyzing chlorination of acetic acid
Wang, Li-Sheng,Song, Guo-Qiang,Meng, Ying,Li, Shou-Gao,Li, Fu-Xiang
, p. 8997 - 8999 (2013)
In this paper, the chloroacetic acid has been synthesized with the acetic anhydride catalyzing chlorination of acetic acid by microwave irradiation. The volume fraction of acetic anhydride in acetic acid, reaction time, microwave power and reaction temperature have been investigated in the self-designed experimental device. The results showed that the optimum conditions were the volume fraction of acetic anhydride in acetic acid of 20 %, reaction time of 3.5 h, microwave power of 300 W, reaction temperature of 95 °C, the yield of chloroacetic acid was 94.31 % and the selectivity was 93.01 %. Compared with ordinary heating, the selectivity and the reaction rate of using microwave irradiation were apparently improved.
Discovery of novel triazolophthalazine derivatives as DNA intercalators and topoisomerase II inhibitors
Sakr, Helmy,Ayyad, Rezk R.,El-Helby, Ali A.,Khalifa, Mohamed M.,Mahdy, Hazem A.
, (2021)
A new series of triazolophthalazine derivatives was designed and synthesized as topoisomerase II (Topo II) inhibitors and DNA intercalators. The synthesized derivatives were evaluated in vitro for their cytotoxic activities against three human cancer cell lines: HepG2, MCF-7, and HCT-116 cells. Compound IXb was the most potent counterpart with IC50 values of 5.39 ± 0.4, 3.81 ± 0.2, and 4.38 ± 0.3 μM, as it was about 1.47, 1.77, and 1.19 times more active than doxorubicin (IC50 = 7.94 ± 0.6, 6.75 ± 0.4, and 5.23 ± 0.3 μM) against HepG2, MCF-7, and HCT-116 cells, respectively. Additionally, the binding affinity of the synthesized compounds toward the DNA molecule was assessed using the DNA/methyl green assay. Compound?IXb showed an excellent DNA binding affinity with an IC50 value of 27.16 ± 1.2 μM, which was better than that of the reference drug doxorubicin (IC50 = 31.02 ± 1.80 μM). Moreover, compound IXb was the most potent member among the tested compounds when investigated for their Topo II inhibitory activity. Furthermore, compound IXb induced apoptosis in HepG2 cells and arrested the cell cycle at the G2/M phase. Additionally, compound IXb showed Topo II poisoning effects at 2.5 μM and Topo II catalytic inhibitory effects at 5 and 10 μM. Finally, molecular docking studies were carried out against the DNA–Topo II complex and DNA, to investigate the binding patterns of the designed compounds.
Activation reactions of 1,1-dialkoxoalkanes and unsaturated O-donors by titanium tetrafluoride
Marchetti, Fabio,Pampaloni, Guido,Biancalana, Lorenzo
, p. 135 - 139 (2012)
The reactivity of TiF4 with a variety of non cyclic 1,1-dialkoxoalkanes [CH2(OR)2, R = Me, Et, Me 2C(OMe)2, MeCH(OEt)2, ClCH2CH(OEt) 2, CH(OMe)3, PhCCCH(OEt)2], 1,3-dioxolane, N2CHCO2Et and 1,2-epoxybutane has been investigated. Activation, including fragmentation and/or rearrangement of the organic moiety, has been observed at room temperature in some cases; it generally occurs unselectively via C-O bond fission and the formation of new C-O, C-H and C-C bonds. Small differences in the structure of the organic substrate may determine significant differences in the reactivity with TiF4.
An efficient chemoenzymatic synthesis of the bactericide lapyrium chloride
Rustoy, Eduardo M.,Baldessari, Alicia
, p. 4628 - 4632 (2005)
An efficient route for large-scale preparation of lapyrium chloride, a broad-spectrum antimicrobial surfactant, was developed from chloroacetic acid in four steps, three of them enzymatic. Due to the chemoselective behavior of the biocatalysts, lapyrium chloride was obtained in a high degree of purity and yield, from mild reaction conditions and following a low environmental impact methodology. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
Catalytic esterifications of carboxylic acids and alcohols by sodium bisulfate monohydrate
Li, Yi-Qun
, p. 3901 - 3903 (1999)
The efficient esterification of primary and secondary alcohols with aliphatic carboxylic acids in the presence of a catalytic amount of sodium bisulfate monohydrate to afford the corresponding esters in high yields.
Using remote substituents to control solution structure and anion binding in lanthanide complexes
Tropiano, Manuel,Blackburn, Octavia A.,Tilney, James A.,Hill, Leila R.,Placidi, Matteo P.,Aarons, Rebecca J.,Sykes, Daniel,Jones, Michael W.,Kenwright, Alan M.,Snaith, John S.,Sorensen, Thomas Just,Faulkner, Stephen
, p. 16566 - 16571 (2013)
A study of the anion-binding properties of three structurally related lanthanide complexes, which all contain chemically identical anion-binding motifs, has revealed dramatic differences in their anion affinity. These arise as a consequence of changes in the substitution pattern on the periphery of the molecule, at a substantial distance from the binding pocket. Herein, we explore these remote substituent effects and explain the observed behaviour through discussion of the way in which remote substituents can influence and control the global structure of a molecule through their demands upon conformational space. Peripheral modifications to a binuclear lanthanide motif derived from α,α′-bis(DO3 Ayl)-m-xylene are shown to result in dramatic changes to the binding constant for isophthalate. In this system, the parent compound displays considerable conformational flexibility, yet can be assumed to bind to isophthalate through a well-defined conformer. Addition of steric bulk remote from the binding site restricts conformational mobility, giving rise to an increase in binding constant on entropic grounds as long as the ideal binding conformation is not excluded from the available range of conformers.
A simple criterion for gas chromatography/mass spectrometric analysis of thermally unstable compounds, and reassessment of the by-products of alkyl diazoacetate synthesis
Kornilova, Tatiana A.,Ukolov, Anton I.,Kostikov, Rafael R.,Zenkevich, Igor G.
, p. 461 - 466 (2013)
Rationale: A principal limitation of gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) is the thermal instability of analytes. We propose that the injector and column temperatures should not exceed the atmospheric pressure boiling point, without decomposition, of the highest homologue of the series being analyzed, instead of the time-consuming procedure of obtaining chromatograms using different temperatures. Methods: A series of thermally unstable diazocarbonyl compounds, alkyl diazoacetates (predicted limit of stability approx. 140 °C, the boiling point of ethyl diazoacetate), was selected for GC/MS analysis using standard equipment. Different GC separation conditions were selected so that the retention temperatures of target compounds were both below and above 140°C. Results: Analyzing alkyl diazoacetates within their thermal stability range permitted reanalysis of their typical synthesis by-products. No dialkyl fumarate or maleate impurities, principal decomposition products which have often been reported previously, were found. Instead, alkyl esters of glycolic acid nitrate, O2NOCH 2CO2R, and 'pseudo-dimeric' products, ROCO[C 2H3NO]CO2R, were discovered for the first time. Conclusions: Avoiding the decomposition of thermally unstable organic compounds during GC and/or GC/MS analysis requires estimating their degradation temperature limits. This limit can be estimated as being equal to the atmospheric pressure boiling point of the highest homologue in the homologous series under consideration that does not decompose on boiling. Copyright
REDUCTIVE DEHALOGENATION OF α-HALOGENATED CARBONYL AND CYANO COMPOUNDS WITH THE HEXAMETHYLDISILANE/TETRAKIS(TRIPHENYLPHOSPHINE)PALLADIUM SYSTEM
Urata, Hisao,Suzuki, Hiroharu,Moro-Oka, Yoshihiko,Ikawa, Tsuneo
, p. 367 - 374 (1982)
Treatment of α-halogenated carbonyl or cyano compounds with hexamethyldisilane in the presence of catalytic amounts of tetrakis(triphenylphosphine)-palladium gives the corresponding parent carbonyl or cyano compounds in excellent yields via oxy-?-allyl(trimethylsilyl)palladium intermediates.
CHLORINATING PROPERTIES OF THE TRIMETHYLCHLOROSILANE-POTASSIUM BROMATE-DMF SYSTEM
Zav'yalov, S. I.,Sitkareva, I. V.,Ezhova, G. I
, p. 356 - 358 (1992)
β-Dicarbonyl compounds such as ethyl acetoacetate, dimedone, and Meldrum's acid derivatives undergo monochlorination by the action of a mixture of ClSiMe3 and KBrO3 in DMF at ca. 20 deg C. Keywords: β-dicarbonyl compounds, monochlorination.
