1,721,188 research outputs found
New Chiral BINOL‐Based Phosphates for Enantioselective [Au(I)]‐Catalyzed Dearomatization of β‐Naphthols with Allenamides
Full text linkNew chiral BINOL-based phosphate counterions have been synthesized, fully characterized, and employed in the enantioselective gold-catalyzed dearomatization of -naphthols with
allenamides. A range of densely functionalized C1-allylated naphthalenones were realized under mild conditions and high levels of chemo-, regio- and stereoselectivity (ee up to 95 %)
Redox-Neutral Metal-Free Three-Component Carbonylative Dearomatization of Pyridine Derivatives with CO2
No full textThe TBD (1,3,5-triazabicyclodec-5-ene) assisted three-component carbonylation of pyridine-2-methana- mines is documented by means of CO2 as a benign CO surrogate. The redox-neutral methodology enables the re- alization of densely functionalized imidazo-pyridinones in high yields (up to 93%) and excellent chemoselectivity. Combined computational and experimental investigations revealed an unprecedented RCOCl/TBD concerted electro- philic activation of carbon dioxide
Ruthenium-Thymine Acetate binding modes
No full textNucleobases coordinated to Ruthenium centres have shown several promising properties for cancer treatments, demonstrating to have efficiency comparable to that of cis-Pt compounds, limiting toxic effects to intact cells and overcoming the drugs resistance after longer treatments. Thymine acetate (THAc) is proposed as a biomimetic model ligand to design potential Ruthenium-based antitumor drugs. Herein we report the reaction between Ru(H)2(CO)(PPh3)3, 1 and THAcH. The X-ray structure of the mono-,dihapto-thymine acetate species [(k1-O)(k2-O,O)Ru(THAc)2(CO)(PPh3)2] 2, unexpectedly exhibits cis-location for acetate ligands, likely ascribed to the prevalence of H-bonds and -stacking interactions. Conversely, DFT-calculations and NMR spectra suggest lower energy for the trans form where there are no contacts between the bulky phosphines. The DFT-calculated energies suggest the nature for NMR-intercepted plausible k1- or k2-intermediates. The carboxy-metal coordination is able to stabilize enol-tautomers through supramolecular H-interactions. The rotations of k1- and k2-acetate side arm of the THAc have also been exploited by correlating NMR signal patterns with the DFT energies.
Figure 1: Torsional barrier of k1-(O) 3 and k2-(O,O)
Organometallic ruthenium(II) scorpionate as topo IIa inhibitor; in vitro binding studies with DNA, HPLC analysis and its anticancer activity
No full textNew organoruthenium [(h6-arene)RuII(L)Cl]Cl (1: arene 1⁄4 p-cymene, L 1⁄4 L1; 2: arene 1⁄4 p-cymene, L 1⁄4 L2; 3: arene 1⁄4 benzene, L 1⁄4 L1; 4: arene 1⁄4 benzene; L 1⁄4 L2; L1 1⁄4 bis(3,5-dimethylpyrazolyl)parabenzoic acid, L2 1⁄4 bis(3,5-dimethylpyrazolyl)metabenzoic acid) have been synthesized and characterized by analytical and spectroscopic methods. The molecular structure of [(h6-p-cymene)RuCl(L1)]Cl (1) was determined by single crystal X-ray diffraction studies. Preliminary in vitro binding studies of 1e4 with CT DNA were carried out by employing various biophysical techniques which revealed their avid DNA binding via noncovalent binding mode viz; partial intercalation of the h6-arene group as well as electrostatic surface interaction through one oxygen atom of the phosphate backbone of the DNA helix; however, complexes
1 and 3 display higher binding propensity in comparison to 2 and 4, as quantified by Kb. The interaction was further analysed by HPLC technique. The results of the cleavage experiments of pBR322 DNA with 1 and 3 displayed significantly good cleavage at 20e40 mM, following the oxidative pathway. These findings have revealed that the hydrophobic arene, and the chloride leaving group have important roles in the novel mechanism of recognition of DNA by (h6-arene)ruthenium(II) complexes, and will aid the design of more effective anticancer complexes, as well as new site-specific DNA reagents. Furthermore, the anticancer activity of the complexes 1 and 3 on 15 cell lines of different histological origin has been studied. It has been observed that 1 exhibits higher cytotoxicity than 3, and the cells undergo apoptotic cell death
Convenient synthesis of polycyclic N(1)-C(2)-fused oxazino-indolones via [Au(I)] catalyzed hydrocarboxylation of allenes
Full text linkA new [Au(I)] catalyzed intramolecular hydrocarboxylation of allenes is presented as a valuable synthetic route to oxazino-indolones. The use of 3,5-(CF3)2–C6H3–ImPyAuSbF6 as the optimal catalyst (5 mol%) was necessary to guarantee (i) wide tolerance of functional groups, (ii) mild reaction conditions (r.t., 16 h), and (iii) high yields (up to 90%). Preliminary attempts towards an enantioselective version (81 : 19 er) are also documented by means of a new family of chiral C1-symmetric ImPyAuCl complexes
Synthesis of five-coordinate Pt(II) complexes containing organogermanium fragments in axial position. Structure of [PtCl(GePh2Cl)(2,9-Me2-1,10-phen)(CH2=CH2)]
No full textScandium catalysed stereoselective thio-allylation of allenyl-imidates
No full textThe site-selective thio-allylation of electron-deficient 1,2-dienes is documented under scandium catalysis. The methodology enables the realization of alpha-beta unsaturated, beta-thio, gamma-allyl carboxylic acid derivatives via a one-pot Lewis acid promoted Michael addition/[3,3]-sigmatropic rearrangement sequence (20 examples) in high yields (up to 95%). Full rationalization of the reaction mechanism and stereochemical outcome is provided via DFT simulation
Visible-Light-Driven Synthesis of 1,3,4-Trisubstituted Pyrroles from Aryl Azides
No full textThe synthesis of 1,3,4-trisubstituted pyrroles via visible-light mediated photoredox catalyzed condensation of arylazides and aldehydes has been reported herein. The methodology avoids the use of stoichiometric oxidants and provides the corresponding N-containing arenes in good yields (up to 78%) and mild conditions. Mechanistic rationale is provided via a dedicated and combined spectroscopic/experimental investigations
CN coupling between μ-aminocarbyne and nitrile ligands promoted by tolylacetylide addition to [Fe2{μ-CN(Me)(Xyl)}(μ-CO)(CO)(NCCMe3)(Cp)2][SO3CF3]
No full textCN coupling between μ-aminocarbyne and nitrile ligands promoted by tolylacetylide addition to [Fe2{μ-CN(Me)(Xyl)}(μ-CO)(CO)(NCCMe3)(Cp)2][SO3CF3
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