Reactions of the technetium(I) nitrosyl complex Tc(NO)(Cp)(PPhsub.3)Cl with triphenylphosphine chalcogenides EPPhsub.3 (E = O, S, Se), and Ag(PFsub.6) in a CHsub.2Clsub.2/MeOH mixture (v/v, 2/1) ...result in an exchange of the chlorido ligand and the formation of Tc(NO)(Cp)(PPhsub.3)(EPPhsub.3)(PFsub.6) compounds. The cationic acetonitrile complex Tc(NO)(Cp)(PPhsub.3)(NCCHsub.3)sup.+ is formed when the reaction is conducted in NCCHsub.3 without additional ligands. During the isolation of the corresponding PFsub.6 sup.− salt a gradual decomposition of the anion was detected in the solvent mixture applied. The yields and the purity of the product increase when the BFsub.4 sup.− salt is used instead. The acetonitrile ligand is bound remarkably strongly to technetium and exchange reactions readily proceed only with strong donors, such as pyridine or ligands with ‘soft’ donor atoms, such as the thioether thioxane. Substitutions on the cyclopentadienyl ring do not significantly influence the ligand exchange behavior of the starting material. sup.99Tc NMR spectroscopy is a valuable tool for the evaluation of reactions of the complexes of the present study. The extremely large chemical shift range of this method allows the ready detection of corresponding ligand exchange reactions. The observed sup.99Tc chemical shifts depend on the donor properties of the ligands. DFT calculations support the discussions about the experimental results and provide explanations for some of the unusual findings.
The first diastereoselective synthesis of (−)-1-epi-lentiginosine from a common chiral trans-epoxyamide derived from 2-pyridincarbaldehyde is reported. This methodology involves a sequential oxirane ...ring opening and intramolecular 5-exo-tet cyclization of tosylate trans-epoxyalcohol to afford a diastereomeric mixture of indolizinium salts in a one-pot fashion, followed by regio- and diastereospecific pyridinium ring reduction.
The 1,2,3triazin-4(3H)-one ring is a synthetically important molecular platform for a variety of chemical transformations. Despite this, currently, there has been little research on the reaction of ...the thermal opening of the 1,2,3triazin-4(3H)-one nucleus. In this work, we describe the synthetic potential of anthra1,2-d1,2,3triazine-4,7,12(3H)-trione in the reaction of the thermal opening of a cycle following the 4+2-cycloaddition reaction with a number of pyridine derivatives and quinoline. It is shown that this method is effective for the synthesis of the 6H-naphtho2,3-Hpyrido(quinolino)2,1-bquinazoline-6,9,14-trione system. We also investigate the influence of the position of substituents in the structure of pyridine on the formation characteristics of the target products.
A simple synthetic method was developed to prepare 4Agpy.sub.2ClO.sub.4·Agpy.sub.4ClO.sub.4 in a low-temperature decomposition process of Agpy.sub.4ClO.sub.4. A detailed IR, Raman and far-IR study ...including factor group analysis has been performed, and the assignation of bands is given. The compound decomposes quickly with a multistep ligand loss process with the formation of Agpy.sub.2ClO.sub.4 and AgClO.sub.4 intermediates and AgCl as an end product around ~ 85, ~ 350 and 450 °C, respectively. During the first decomposition step, a small fraction of the ligands is lost in a redox reaction: perchlorate oxidizes the pyridine, forming carbon, carbon dioxide, water and NO, while it itself is reduced into AgCl. In the next step, when AgClO.sub.4 forms after complete ligand loss and reacts with the carbon formed in the degradation of pyridine at lower temperatures and produces NO, CO.sub.2 and H.sub.2O. This reaction becomes possible because the AgCl formed in the redox reactions makes a eutectic melt with AgClO.sub.4 in situ, which is a favorable medium for the carbon oxidation reaction. AgCl is known to reduce the temperature of decomposition of AgClO.sub.4, in which process forms AgCl as well as O.sub.2 and so is an autocatalytic process. The loss and degradation of pyridine ligand are endothermic; the redox reactions including carbon oxidation and AgClO.sub.4 decomposition into AgCl and O.sub.2 are exothermic. The amount of absorbed/evolved heats corresponding to these processes was determined by DSC both under N.sub.2 and O.sub.2 atmospheres.
4-Hydroxymethyl-2-hetaryl(hetaroyl)furo2,3-cpyridines, the products of furan cyclization of pyridoxal with acylmethyl- and heteroarylmethyl halides, easily react with thionyl chloride in DMF to form ...new series of 4-chloromethyl-2-heteroaryl2,3-cpyridines. Further action of primary or secondary amines on these chloromethyl derivatives leads to the nucleophilic substitution of chlorine atoms with the formation of 4-aminomethyl-2-heteroaryl2,3-cpyridines. The study of anti-infective activity of the 4-RCH.sub.2-furo2,3-cpyridines (R = OH, Cl, NR.sup.1R.sup.2) showed significant protistocidal and moderate antibacterial activity of some of representatives of these compounds.
Recent developments in the synthesis of imidazo1,2-apyridines via the transition metal-catalyzed three-component heterocyclization of aldehyde, 2-aminopyridine, and alkyne are discussed in this ...highlight.
Two coordination polymers, Fe(Lsup.OBF sub.3)(CHsub.3COO)(CHsub.3CN)sub.2sub.n*nCHsub.3CN and Fe(Lsup.O−)sub.2AgNOsub.3BFsub.4*CHsub.3OHsub.n*1.75nCHsub.3OH*nHsub.2O (Lsup.O− = ...3,3′-(4-(4-cyanophenyl)pyridine-2,6-diyl)bis(1-(2,6-dichlorophenyl)-1H-pyrazol-5-olate)), were obtained via a PCET-assisted process that uses the hydroxy-pyrazolyl moiety of the ligand and the iron(II) ion as sources of proton and electron, respectively. Our attempts to produce heterometallic compounds under mild conditions of reactant diffusion resulted in the first coordination polymer of 2,6-bis(pyrazol-3-yl)pyridines to retain the core Nsub.3(L)MNsub.3(L). Under harsh solvothermal conditions, a hydrogen atom transfer to the tetrafluoroborate anion caused the transformation of the hydroxyl groups into OBFsub.3 in the third coordination polymer of 2,6-bis(pyrazol-3-yl)pyridines. This PCET-assisted approach may be applicable to produce coordination polymers and metal-organic frameworks with the SCO-active core Nsub.3(L)MNsub.3(L) formed by pyrazolone- and other hydroxy-pyridine-based ligands.
Hetarenesulfenyl-Camphene Startseva, V. A; Kuznetsov, I. V; Nikitina, L. E ...
Chemistry of natural compounds,
07/2015, Letnik:
51, Številka:
4
Journal Article
Recenzirano
Novel S- and Se-containing terpenoids were prepared by reacting (+)-camphene with N-heterocyclic selenyland sulfenyl chlorides.
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