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.
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.
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.
