864264-99-3Relevant articles and documents
How Metal Ion Lewis Acidity and Steric Properties Influence the Barrier to Dioxygen Binding, Peroxo O-O Bond Cleavage, and Reactivity
Yan Poon, Penny Chaau,Dedushko, Maksym A.,Sun, Xianru,Yang, Guang,Toledo, Santiago,Hayes, Ellen C.,Johansen, Audra,Piquette, Marc C.,Rees, Julian A.,Stoll, Stefan,Rybak-Akimova, Elena,Kovacs, Julie A.
supporting information, p. 15046 - 15057 (2019/10/21)
Herein we quantitatively investigate how metal ion Lewis acidity and steric properties influence the kinetics and thermodynamics of dioxygen binding versus release from structurally analogous Mn-O2 complexes, as well as the barrier to Mn peroxo O-O bond cleavage, and the reactivity of Mn oxo intermediates. Previously we demonstrated that the steric and electronic properties of MnIII-OOR complexes containing N-heterocyclic (NAr) ligand scaffolds can have a dramatic influence on alkylperoxo O-O bond lengths and the barrier to alkylperoxo O-O bond cleavage. Herein, we examine the dioxygen reactivity of a new MnII complex containing a more electron-rich, less sterically demanding NAr ligand scaffold, and compare it with previously reported MnII complexes. Dioxygen binding is shown to be reversible with complexes containing the more electron-rich metal ions. The kinetic barrier to O2 binding and peroxo O-O bond cleavage is shown to correlate with redox potentials, as well as the steric properties of the supporting NAr ligands. The reaction landscape for the dioxygen chemistry of the more electron-rich complexes is shown to be relatively flat. A total of four intermediates, including a superoxo and peroxo species, are observed with the most electron-rich complex. Two new intermediates are shown to form following the peroxo, which are capable of cleaving strong X-H bonds. In the absence of a sacrificial H atom donor, solvent, or ligand, serves as a source of H atoms. With TEMPOH as sacrificial H atom donor, a deuterium isotope effect is observed (kH/kD = 3.5), implicating a hydrogen atom transfer (HAT) mechanism. With 1,4-cyclohexadiene, 0.5 equiv of benzene is produced prior to the formation of an EPR detected MnIIIMnIV bimetallic species, and 0.5 equiv after its formation.
SUBSTITUTED N-(1H-INDAZOL-4-YL)IMIDAZO[1,2-a]PYRIDINE-3-CARBOXAMIDE COMPOUNDS AS TYPE III RECEPTOR TYROSINE KINASE INHIBITORS
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Page/Page column 133, (2012/06/30)
Compounds of Formula I: and pharmaceutically acceptable salts thereof in which R1, R2, R3, R4, R5 and R6 have the meanings given in the specification, are inhibitors of cFMS and are useful in the treatment of fibrosis, bone-related diseases, cancer, autoimmune disorders, inflammatory diseases, cardiovascular diseases, pain and burns in a mammal
