25335-74-4Relevant articles and documents
Cp? versus Bis-carbonyl iridium precursors as CH oxidation precatalysts
Huang, Daria L.,Vinyard, David J.,Blakemore, James D.,Hashmi, Sara M.,Crabtree, Robert H.
, p. 199 - 206 (2017/11/27)
We previously reported a dimeric IrIV-oxo species as the active water oxidation catalyst formed from a Cp?Ir(pyalc)Cl {pyalc = 2-(2′-pyridyl)-2-propanoate} precursor, where the Cp? is lost to oxidative degradation during catalyst activation; this system can also oxidize unactivated CH bonds. We now show that the same Cp?Ir(pyalc)Cl precursor leads to two distinct active catalysts for CH oxidation. In the presence of external CH substrate, the Cp? remains ligated to the Ir center during catalysis; the active species-likely a highvalent Cp?Ir(pyalc) species-will oxidize the substrate instead of its own Cp?. If there is no external CH substrate in the reaction mixture, the Cp? will be oxidized and lost, and the active species is then an iridium-μ-oxo dimer. Additionally, the recently reported Ir(CO)2(pyalc) water oxidation precatalyst is now found to be an efficient, stereoretentive CH oxidation precursor. We compare the reactivity of Ir(CO)2(pyalc) and Cp?Ir(pyalc)Cl precursors and show that both can lose their placeholder ligands, CO or Cp?, to form substantially similar dimeric IrIV-oxo catalyst resting states. The more efficient activation of the bis-carbonyl precursor makes it less inhibited by obligatory byproducts formed from Cp? degradation, and therefore the dicarbonyl is our preferred precatalyst for oxidation catalysis.
Conformation of Nα-substituted hydrazino acetamides in CDCl3, the precious help of the analysis of Δδ between amidic hydrogens, and correlation to the conformation of aza-β3- peptides
Salauen, Arnaud,Favre, Annaick,Le Grel, Barbara,Potel, Michel,Le Grel, Philippe
, p. 150 - 158 (2007/10/03)
We studied the conformation of a series of primary amides in a solution of chloroform. Classical NMR tools such as dilution experiments, influence of DMSO, and 2D-NOESY, together with X-ray diffraction, were combined with an analysis of the difference of the chemical shift Δδ between the geminal amidic protons. This study was addressed in order to understand the conformation adopted by hydrazino acetamides 1a and 1b as model compounds for aza-β3-peptides. In this manner, it was possible to show that the amidic group of these compounds acts as a H-bond donor and interacts with two different H-bond acceptors. We concluded that the hydrazinoturn, a specific bifurcated H-bond system observed in the solid state, is also the preferred conformation of hydrazino acetamides 1a and 1b in solution. Our results show that the short-range interaction with the Nα-nitrogen lone pair not only stabilizes the C8 pseudocycle but could also contribute to the folding process of aza-β3-peptides. In light of this, it could explain why aza-β3-peptides develop a different H-bond network in comparison to their isosteric β3-peptides analogues. Our work is in keeping with the recent interest of hydrazino peptides as an extension of the β-peptide concept.
Mapping of the active site of rat kidney γ-glutamyl transpeptidase using activated esters and their amide derivatives
Castonguay, Roselyne,Lherbet, Christian,Keillor, Jeffrey W.
, p. 4185 - 4191 (2007/10/03)
The enzyme γ-glutamyl transpeptidase (GGT), implicated in many physiological processes, catalyses the transfer of a γ-glutamyl from a donor substrate to an acyl acceptor substrate, usually an amino acid or a peptide. In order to investigate which moieties of the donor substrate are necessary for recognition by GGT, the structure of the well-recognized substrate L-γ-glutamyl-p-nitroanilide was modified. Several activated esters and their amide derivatives were synthesized and used as substrates. Kinetic (Km and Vmax) and inhibition constants (Ki) were measured and reveal that almost the entire γ-glutamyl moiety is necessary for recognition in the binding site of the donor substrate. The implied presence of certain complementary amino acids in this substrate binding site will allow the more rational design of various substrate analogues and inhibitors.
The Preference Profile in Ruthenium Tetroxide Oxidations
Ranganathan,Muraleedharan,Bhattacharyya,Kundu
, p. 583 - 589 (2007/10/03)
The preference profile of RuVIII-generated in a catalytic cycle, maintained by periodate in carbon tetrachloride : acetonitrile : water -has been examined from a practical vantage using tyrosine, phenylalanine and lysine as primary substrates. Other factors such as pH, acetonitrile versatility, transport of oxidized ruthenium species across the layers and hydrophobic alignment, influence the course of the reaction. Aryl oxidation, which takes place at the organic interface, is strongly influenced by ring perturbation (pOH-C6H4CH2CH,++; PhCH2CH,+, PhCH2O,+; PhCH2OCONH(Z),-; PhCH2OCO,-; pOH-C6H4CH2CO,+; PhCH2CO,-; PhCO,-). In the case of tyrosine, the preference profile switches from ring oxidation at pH 3 to α-amino group oxidation at pH 6 and 9, whilst with phenylalanine, the amino group is exclusively oxidized even at pH 3. With lysine, the reasonable differences in pKa between the α-amino group (8.95) and the ω-amino unit (10.53), elicit sharp preferences. At pH 3 as well as at 6, the α-amino group is selectively oxidized leading to glutaric acid mono-amide, a finding supported by studies with Nα and Nω protected lysines. Lysine and arginine side-chains are found largely unaffected by the reagent at pH 3 and 6. The findings have been rationalized on the basis of an integrated mechanism. The work has endeavoured to reconcile seemingly conflicting reports in the literature and to project the reagent for selective modifications in synthesis.
Herbicidal glutarimides
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, (2008/06/13)
This invention relates to glutarimide compounds exhibiting herbicidal activity having the structure STR1 wherein A is carbonyl, thiocarbonyl or methylene, A1 is carbonyl or methylene, Q is O or (CH2)n where n is 0 or 1, D is CH or N and R, R1, R2, T, X, Y and Z are as defined within, compositions containing these compounds and methods of using these compounds as herbicides and algicides.
Herbicidal glutaramic acids and derivatives
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, (2008/06/13)
This invention relates to glutaramic acids and derivatives exhibiting herbicidal activity having the structure STR1 wherein A is a carboxylic acid or a derivative thereof, D is CH or N, and R, R1, R2, T, X, Y, and Z are as defined within, compositions containing these compounds and methods of controlling weeds with these compounds.
Intramolecular Influence of a Carboxylic Function on Platinium Blue Synthesis. A systematic Study of Complexes Originating from Acid Amides
Arrizabalaga, Philippe,Castan, Paule,Laurent, Jean-Pierre
, p. 4814 - 4818 (2007/10/02)
The use of acid amide as ligand for obtaining platinium blue has been investigated.While blue compounds are generally obtained by using the hydrolysis product of cis-dichlorodiammineplatinum(II) as platinum surce, with such ligands the reaction occurs very readily using potassium tetrachloroplatinate(II).The role of the carboxylic function which offers here a primary ligating site to platinum is evidenced.The compounds obtained have been characterized by UV-visible spectral measurments, Ce(IV) oxydative titration , ESR spectroscopy, and magnetic properties.Antitumoral activity toward leukemia L1210 and sarcoma 180 is reported for two of thesecompounds.As a first step for this antitumor study, these compounds have been found to be inactive toward Leukemia while they presnt intersting activity toward Sarcoma.
Organic compounds substituted heptadeca-5,9- and 5,10-dienoic acid
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, (2008/06/13)
The present invention provides novel substituted heptadeca-5,9- and 5,10-dienoic acid and similar fatty acid compounds which are derivatives of certain prostaglandins and are potent thromboxane A2 inhibitors. By virtue of this pharmacological property, they represent useful pharmacological agents for a wide variety of purposes.
1,3-Diazepinones. 2. The Correct Structure of Squamolone as 1-Carbamoyl-2-pyrrolidinone and Synthesis of Authentic Perhydro-1,3-diazepine-2,4-dione
Marquez, Victor E.,Kelley, James A.,Driscoll, John S.
, p. 5308 - 5312 (2007/10/02)
The natural product squamolone,previously reported as 4-oxoperhydro-1,3-diazepin-2-one (1), was found to be instead 1-carbamoyl-2-pyrrolidinone (2).An unequivocal synthesis of the diazepinedione 1 starting from glutaric acid monoamide (6) produced the desired compound in five steps.Diborane reduction of 1 yielded the known perhydro-1,3-diazepin-2-one (10, tetramethyleneurea), confirming the seven-membered-ring structure of 1.A detailed analysis of the IR, NMR, and mass spectra of squamolone (2) and its isomer 1 is presented.A one-step synthesis of squamolone (2) starting with 4-aminobutyric acid 3 is reported.
