2564-83-2Relevant articles and documents
A Structurally Characterized Nonheme Cobalt-Hydroperoxo Complex Derived from Its Superoxo Intermediate via Hydrogen Atom Abstraction
Wang, Chun-Chieh,Chang, Hao-Ching,Lai, Yei-Chen,Fang, Huayi,Li, Chieh-Chin,Hsu, Hung-Kai,Li, Zong-Yan,Lin, Tien-Sung,Kuo, Ting-Shen,Neese, Frank,Ye, Shengfa,Chiang, Yun-Wei,Tsai, Ming-Li,Liaw, Wen-Feng,Lee, Way-Zen
, p. 14186 - 14189 (2016)
Bubbling O2 into a THF solution of CoII(BDPP) (1) at -90 °C generates an O2 adduct, Co(BDPP)(O2) (3). The resonance Raman and EPR investigations reveal that 3 contains a low spin cobalt(III) ion bound to a superoxo ligand. Significantly, at -90 °C, 3 can react with 2,2,6,6-tetramethyl-1-hydroxypiperidine (TEMPOH) to form a structurally characterized cobalt(III)-hydroperoxo complex, CoIII(BDPP)(OOH) (4) and TEMPO?. Our findings show that cobalt(III)-superoxo species are capable of performing hydrogen atom abstraction processes. Such a stepwise O2-activating process helps to rationalize cobalt-catalyzed aerobic oxidations and sheds light on the possible mechanism of action for Co-bleomycin.
An Iron(III) Superoxide Corrole from Iron(II) and Dioxygen
Albert, Therese,Goldberg, David P.,Mo?nne-Loccoz, Pierre,Sacramento, Jireh Joy D.,Siegler, Maxime
, (2021/12/03)
A new structurally characterized ferrous corrole [FeII(ttppc)]? (1) binds one equivalent of dioxygen to form [FeIII(O2?.)(ttppc)]? (2). This complex exhibits a 16/18O2-isotope sensitive ν(O-O) stretch at 1128 cm?1 concomitantly with a single ν(Fe-O2) at 555 cm?1, indicating it is an η1-superoxo (“end-on”) iron(III) complex. Complex 2 is the first well characterized Fe-O2 corrole, and mediates the following biologically relevant oxidation reactions: dioxygenation of an indole derivative, and H-atom abstraction from an activated O?H bond.
Singlet Oxygen Generation from a Water-Soluble Hypervalent Iodine(V) Reagent AIBX and H2O2: An Access to Artemisinin
Hu, Ze-Nan,Shen, Hui-Jie,Zhang, Chi
, (2021/06/21)
Herein, we report an efficient method for the chemical generation of 1O2 by treatment of H2O2 with AIBX, a highly water-soluble, bench-stable, recyclable hypervalent iodine(V) reagent developed by our group. The generation of 1O2 was confirmed by the following results: (1) capture of 1O2 with the sodium salt of anthracene-9,10-bis(ethanesulfonate) produced the corresponding endoperoxide and (2) TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) produced by the oxidation of 2,2,6,6-tetramethylpiperidine with 1O2 generated using the AIBX/H2O2 system was detected by electron spin resonance spectroscopy. To illustrate the potential utility of this method for organic synthesis, we used the AIBX/H2O2 system to perform typical reactions of 1O2: [2 + 2]/[4 + 2] cycloadditions, Schenck ene reactions, and heteroatom oxidation reactions, which afforded the corresponding products in high yields. Moreover, we used the method to synthesize the antimalarial drug artemisinin. Finally, we demonstrated that AIBX could be regenerated after the reaction by means of a workup involving extraction and removal of water to obtain a precursor of AIBX, which could then be re-oxidized.
Combining Structural with Functional Model Properties in Iron Synthetic Analogue Complexes for the Active Site in Rabbit Lipoxygenase
Bonck, Thorsten,De Waal Malefijt, Matina Elo?se,Dobbelaar, Emiel,Kelm, Harald,Klein, Johannes E. M. N.,Krüger, Hans-J?rg,Rauber, Christian,Schmitz, Markus
supporting information, p. 13145 - 13155 (2021/09/03)
Iron complexes that model the structural and functional properties of the active iron site in rabbit lipoxygenase are described. The ligand sphere of the mononuclear pseudo-octahedral cis-(carboxylato)(hydroxo)iron(III) complex, which is completed by a tetraazamacrocyclic ligand, reproduces the first coordination shell of the active site in the enzyme. In addition, two corresponding iron(II) complexes are presented that differ in the coordination of a water molecule. In their structural and electronic properties, both the (hydroxo)iron(III) and the (aqua)iron(II) complex reflect well the only two essential states found in the enzymatic mechanism of peroxidation of polyunsaturated fatty acids. Furthermore, the ferric complex is shown to undergo hydrogen atom abstraction reactions with O-H and C-H bonds of suitable substrates, and the bond dissociation free energy of the coordinated water ligand of the ferrous complex is determined to be 72.4 kcal·mol-1. Theoretical investigations of the reactivity support a concerted proton-coupled electron transfer mechanism in close analogy to the initial step in the enzymatic mechanism. The propensity of the (hydroxo)iron(III) complex to undergo H atom abstraction reactions is the basis for its catalytic function in the aerobic peroxidation of 2,4,6-tri(tert-butyl)phenol and its role as a radical initiator in the reaction of dihydroanthracene with oxygen.