- A [2 × 2] nickel(II) grid and a copper(II) square result from differing binding modes of a pyrazine-based diamide ligand
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The potentially bis-terdentate diamide ligand N,N′-bis[2-(2-pyridyl) ethyl]pyrazine-2,3-dicarboxamide (H2LEt) was structurally characterised. Potentiometric titrations revealed rather low pKa values for the deprotonation of the first amide group of H2L Et (14.2) and N,N′-bis(2-pyridylmethyl)pyrazine-2,3- dicarboxamide (H2LMe, 13.1). Two tetranuclear copper(ii) square complexes of H2LEt with a paddle-wheel appearance, in which each ligand strand acts as a linear N3-NO hybrid terdentate-bidentate chelate, have been isolated and structurally characterised. Complex [CuII4(H2LEt) 2(HLEt)2](BF4)6· 3MeCN·0.5H2O (3·3MeCN·0.5H2O), with two nondeprotonated zwitterionic ligand strands and two monodeprotonated ligand strands, is formed in the 1: 1 reaction of H2LEt and Cu(BF4)2·4H2O. It has a polymeric chain structure of tetranuclear subunits connected by N-H...N hydrogen bonds. The same reaction carried out with one equivalent of base gives the related compound [CuII4(HLEt)4](BF 4)4 (4), with all four ligand strands monodeprotonated. It consists of isolated tetranuclear units. In both 3·3MeCN·0.5 H2O and 4 the copper(ii) ions are in five-coordinate N4O environments but the degree of trigonality (τ) differs [3· 3MeCN·0.5H2O 0.14 ≤ τ ≤ 0.26; 4 τ = 0.45]. Under the same reaction conditions as for 4 but using Ni(BF4) 2·6H2O a tetranuclear [2 × 2] grid-type complex, [NiII4(HLEt)4](BF 4)·10H2O (5·10H2O), is formed. The structure determination showed that the nickel(ii) ions have N6 distorted octahedral coordination spheres and all four ligand strands are monodeprotonated and act as N3-N3 bis-terdentate chelates. Magnetic susceptibility data show that the complexes 3·4H2O, 4 and 5·10H2O exhibit very weak antiferromagnetic spin coupling. The energies and multiplicities of the spin states of 3·4H 2O and 4 were determined from the temperature dependence of the magnetic susceptibility and indicate that a singlet state is lowest and the quintet state highest. This is consistent with the X-band EPR spectra of polycrystalline powders of 3·4H2O and 4, measured down to 2.3 K, where the resonances observed at the lowest temperature are due to a triplet state. The g-values of the individual ions of 4 are consistent with the expected dx 2 -y 2 ground state for five-coordinate copper(ii) in an approximately square pyramidal configuration. The Royal Society of Chemistry 2007.
- Klingele, Julia,Boas, John F.,Pilbrow, John R.,Moubaraki, Boujemaa,Murray, Keith S.,Berry, Kevin J.,Hunter, Keith A.,Jameson, Geoffrey B.,Boyd, Peter D. W.,Brooker, Sally
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- Quaternary Stereogenic Centers through Enantioselective Heck Arylation of Acyclic Olefins with Aryldiazonium Salts: Application in a Concise Synthesis of (R)-Verapamil
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We describe herein a highly regio- and enantioselective Pd-catalyzed Heck arylation of unactivated trisubstituted acyclic olefins to provide all-carbon quaternary stereogenic centers. Chiral N,N ligands of the pyrimidine- and pyrazino-oxazoline class were developed for that purpose, providing the desired products in good to high yields with enantiomeric ratios up to >99:1. Both linear and branched substituents on the olefins were well-tolerated. The potential of this new method is demonstrated by the straightforward synthesis of several O-methyl lactols and lactones containing quaternary stereocenters, together with a concise enantioselective total synthesis of the calcium channel blocker verapamil.
- Oliveira, Caio C.,Pfaltz, Andreas,Correia, Carlos Roque Duarte
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supporting information
p. 14036 - 14039
(2016/01/25)
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- Design, synthesis, and biological evaluation of novel tricyclic HIV-1 integrase inhibitors by modification of its pyridine ring
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This communication details both the syntheses and biological evaluation of a novel class of HIV-1 integrase inhibitors. When the quinoline moiety is replaced with the quinoxoline moiety, the antiviral activity is significantly compromised. Similarly, intr
- Metobo, Sammy E.,Jin, Haolun,Tsiang, Manuel,Kim, Choung U.
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p. 3985 - 3988
(2007/10/03)
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- Design and optimization of tricyclic phtalimide analogues as novel inhibitors of HIV-1 integrase
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Human immunodeficiency virus type-1 integrase is an essential enzyme for effective viral replication and hence a valid target for the design of inhibitors. We report here on the design and synthesis of a novel series of phthalimide analogues as integrase
- Verschueren, Wim G.,Dierynck, Inge,Amssoms, Katie I. E.,Hu, Lili,Boonants, Paul M. J. G.,Pille, Geert M. E.,Daeyaert, Frits F. D.,Hertogs, Kurt,Surleraux, Dominique L. N. G.,Wigerinck, Piet B. T. P.
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p. 1930 - 1940
(2007/10/03)
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- PHOSPHONATE ANALOGS OF HIV INTEGRASE INHIBITOR COMPOUNDS
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Novel HIV integrase inhibitor compounds having at least one phosphonate group, protected intermediates thereof, and methods for inhibition of HIV-integrase are disclosed.
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Page/Page column 534
(2010/02/15)
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- HIV INTEGRASE INHIBITORS
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The present invention concerns the compounds having the formula (1), N-oxides, salts, stereoisomeric forms, racemic mixtures, prodrugs, esters and metabolites thereof wherein (a) or (b); A, together with the two carbons of the phenyl ring to which it is attached forms a monocyclic aryl or a monocyclic Het2 ; R1 is hydrogen, halo, nitro, cyano, sultam, sulltim, C3-7cycloalkyl, C(=O)-R5, S(=O)y-R6, OR 7, NR8R9, C(=NR8)-R5, optionally polysubstituted C1-6alkyl, optionally polysubstituted C2-6alkenyl or optionally polysubstituted C2-6alkynyl; R 2 is hydrogen, C3-7cycloalkyl, aryl, Het1, Het2, C(=O)-R5, S(=O)Y-R6 OR7, NR8R9, C=NR8)-R5, or optionally polysubstituted C1-6alkyl, optionally polysubstituted C2-6alkenyl or optionally polysubstituted C2-6alkynyl. It further relates to their use as HIV integrase inhibitors, processes for their preparation as well as pharmaceutical compositions and diagnostic kits comprising them. It also concerns combinations thereof with other anti-retroviral agents, and to their use in assays as reference compounds or as reagents.
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- Pyrazine fused to a cyclic peptide
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The present invention relates to pyrazine fused to a cyclic peptide which is capable of regulating, in particular stimulating, haematopoiesis.
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