1,721,055 research outputs found
Application of the Free Wilson Model to the analysis of three different pharmacological activities tests in benzodiazepines
No full text---The Free-Wilson model has been applied to the analysis of activity data of 55 benzodiazepines derived from Footshock, Inclined Screen and Pentylenetetrazole tests. The comparison of the individual group contributions shows a similar trend for Footshock and Inclined Screen tests, while some differences are observed with respect to the Pentylenetetrazole test. The most relevant differences seem to be associated with the presence of highly electron-withdrawing substituents in positions 7 and 2'
Palladium(II) and platinum(II) pyrrolate-quinoline-imine chlorocomplexes by metal-assisted condensation reactions
No full text
Synthesis, characterization and X-ray Crystal Structure of Gold(III) complexes obtained by addition of hydroxylic molecules to gold(III)-2-pyridinecarboxyhaldehyde) substrate
No full textThe unexpected case of reactions of halogens and interhalogens with halide substituted Pd(II) σ-butadienyl complexes
No full textWe have experimentally studied and theoretically interpreted the addition under stoichiometric conditions of halogens or interhalogens to σ-butadienyl palladium complexes bearing the heteroditopic thioquinolines as spectator ligands. The observed reactions do not involve the expected extrusion of the butadienyl fragment but rather the unpredictable substitution of the halide coordinated to palladium and in some cases also of that bound to the terminal butadienyl carbon. We have explained this peculiar reactivity with a mechanistic hypothesis based on a sequence of selective processes of oxidative addition and reductive elimination involving Pd(iv) intermediates
9-(2-Phenylethyl)-6-(2-thienyl)-9H-purine
No full textIn the title compound [alternative name: 9-benzyl-6-(2-
thienyl)-9H-purine], C16H12N4S, the purine system is not
strictly planar and the dihedral angle between the fused rings
is 1.46°. The packing of the molecules is in ̄uenced by
hydrophobic and hydrophilic interactions
Addition of halogens and interhalogens on palladacyclopentadienyl complexes stabilized by pyridyl−thioether N−S spectator ligands
No full textWe have studied from the experimental and theoretical point of view the oxidative addition of halogens (I2 and Br2) and interhalogens (ICl and IBr) on palladiumcyclopentadienyl complexes bearing heteroditopic pyridyl−thioether spectator ligands. Addition of I2 or of a stoichiometric amount of Br2 to a CDCl3 solution of the starting palladacyclopentadienyl complexes yields the expected palladium−σ−butadienyl derivatives. The bromide derivative in the presence of a further excess of Br2 gives the wanted dibromo−(E, E)−σ−butadienyl and the pyridylthioether palladium(II) dibromide species. The rates of these reactions have been determined. When the interhalogens are used as oxidizing agents the thermodynamically hampered species is formed at first. Only in the case of the reaction of IBr is the formation of the energetically hampered derivative followed by partial isomerization to the most stable complex. The rate of isomerization and the related equilibrium constant between isomers have been measured. On the basis of the experimental evidence and the computational approach we have proposed a plausible energetic path yielding the first formed unexpected species. Finally, the solid state structures of two reaction products were resolved and reported
Synthesis of novel olefin complexes of palladium(0) bearing monodentate NHC, phosphine and isocyanide spectator ligands
No full textWe have synthesized and characterized seventeen new bis-NHC, mixed NHC–phosphines or NHC–isocyanides Pd(0) olefin complexes that can potentially act as catalysts. The complexes were characterized by standard spectroscopic methods and elemental analysis and in two cases by SC-XRD technique. We have analyzed with particular care the thermodynamic and kinetic conditions governing the one-pot synthesis of the mixed complexes. In this respect we tried to validate our results by a dedicated computational study on the mutual distribution of the isomers that could be potentially formed. However, the computational result is not clear-cut owing to the not significant value of the calculated ΔG0. Finally, in one case we have measured the rate of the exchange reaction between not particularly encumbered olefins
Synthesis of C-glycosyl β-amino acids by asymmetric Mannich-type three-component reactions.
No full textC-Galactosyl and C-ribosyl b-amino acids were prepared by one-pot InCl3-catalyzed Mannich-type three-component
condensation (3CC) by combining the corresponding formyl C-glycoside, p-methoxybenzyl amine, and a ketene silyl acetal. In each case the reaction was highly stereoselective and afforded only one single product in good to excellent yields
Synthesis, characterization and a reactivity study of some allyl palladium complexes bearing bidentate hemi-labile carbene or mixed carbene/PPh3ligands
No full textWith the aim at synthesizing novel allyl complexes that can potentially act as catalysts in the Tsuji–Trost catalyzed reaction, we have synthesized and characterized some allyl and 2-Meallyl palladium derivatives with one hemilabile bidentate or two strong mono-coordinating spectator ligands. The hemilabile ligands are constituted by one nitrogen heterocyclic carbene (NHC) fragment acting as the pivot bearing a labile wing with a pyridine nitrogen or sulfur atom as the second stabilizing atom. One of two monodentate ligands is in all cases PPh3whereas the other is a mono- or partially coordinated hemilabile carbene. The complexes were characterized by standard spectroscopic methods and elemental analysis and in two cases by SC-XRD technique. The reactivity of two selected complexes toward the Tsuji–Trost reaction was tested by stoichiometric allyl amination carried out with piperidine and the results of such a mechanistic investigation integrated by a computational study are also reported in this paper
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