123-07-9Relevant articles and documents
Increasing the steric hindrance around the catalytic core of a self-assembled imine-based non-heme iron catalyst for C-H oxidation
Frateloreto, Federico,Capocasa, Giorgio,Olivo, Giorgio,Abdel Hady, Karim,Sappino, Carla,Di Berto Mancini, Marika,Levi Mortera, Stefano,Lanzalunga, Osvaldo,Di Stefano, Stefano
, p. 537 - 542 (2021)
Sterically hindered imine-based non-heme complexes4and5rapidly self-assemble in acetonitrile at 25 °C, when the corresponding building blocks are added in solution in the proper ratios. Such complexes are investigated as catalysts for the H2O2oxidation of a series of substrates in order to ascertain the role and the importance of the ligand steric hindrance on the action of the catalytic core1, previously shown to be an efficient catalyst for aliphatic and aromatic C-H bond oxidation. The study reveals a modest dependence of the output of the oxidation reactions on the presence of bulky substituents in the backbone of the catalyst, both in terms of activity and selectivity. This result supports a previously hypothesized catalytic mechanism, which is based on the hemi-lability of the metal complex. In the active form of the catalyst, one of the pyridine arms temporarily leaves the iron centre, freeing up a lot of room for the access of the substrate.
Kahler et al.
, p. 94 (1960)
Dual-Functional Small Molecules for Generating an Efficient Cytochrome P450BM3 Peroxygenase
Ma, Nana,Chen, Zhifeng,Chen, Jie,Chen, Jingfei,Wang, Cong,Zhou, Haifeng,Yao, Lishan,Shoji, Osami,Watanabe, Yoshihito,Cong, Zhiqi
, p. 7628 - 7633 (2018)
We report a unique strategy for the development of a H2O2-dependent cytochrome P450BM3 system, which catalyzes the monooxygenation of non-native substrates with the assistance of dual-functional small molecules (DFSMs), such as N-(ω-imidazolyl fatty acyl)-l-amino acids. The acyl amino acid group of DFSM is responsible for bounding to enzyme as an anchoring group, while the imidazolyl group plays the role of general acid–base catalyst in the activation of H2O2. This system affords the best peroxygenase activity for the epoxidation of styrene, sulfoxidation of thioanisole, and hydroxylation of ethylbenzene among those P450–H2O2 system previously reported. This work provides the first example of the activation of the normally H2O2-inert P450s through the introduction of an exogenous small molecule. This approach improves the potential use of P450s in organic synthesis as it avoids the expensive consumption of the reduced nicotinamide cofactor NAD(P)H and its dependent electron transport system. This introduces a promising approach for exploiting enzyme activity and function based on direct chemical intervention in the catalytic process.
Convenient synthesis of 3-acyl- and 3-alkyl-1,2-naphthoquinones
Takuwa,Kai
, p. 623 - 625 (1990)
3-Acyl-1,2-naphthalenediols prepared by the photoinduced addition reaction of 1,2-naphthoquinone with alkanals were oxidized with Fremy's salt to give 3-acyl-1,2-naphthoquinones in good yields. The diols were reduced with amalgamated zinc, followed by oxidation to afford 3-alkyl-1,2-naphthoquinones in moderate yields.
Metal-Organic Framework-Confined Single-Site Base-Metal Catalyst for Chemoselective Hydrodeoxygenation of Carbonyls and Alcohols
Antil, Neha,Kumar, Ajay,Akhtar, Naved,Newar, Rajashree,Begum, Wahida,Manna, Kuntal
supporting information, p. 9029 - 9039 (2021/06/28)
Chemoselective deoxygenation of carbonyls and alcohols using hydrogen by heterogeneous base-metal catalysts is crucial for the sustainable production of fine chemicals and biofuels. We report an aluminum metal-organic framework (DUT-5) node support cobalt(II) hydride, which is a highly chemoselective and recyclable heterogeneous catalyst for deoxygenation of a range of aromatic and aliphatic ketones, aldehydes, and primary and secondary alcohols, including biomass-derived substrates under 1 bar H2. The single-site cobalt catalyst (DUT-5-CoH) was easily prepared by postsynthetic metalation of the secondary building units (SBUs) of DUT-5 with CoCl2 followed by the reaction of NaEt3BH. X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy (XANES) indicated the presence of CoII and AlIII centers in DUT-5-CoH and DUT-5-Co after catalysis. The coordination environment of the cobalt center of DUT-5-Co before and after catalysis was established by extended X-ray fine structure spectroscopy (EXAFS) and density functional theory. The kinetic and computational data suggest reversible carbonyl coordination to cobalt preceding the turnover-limiting step, which involves 1,2-insertion of the coordinated carbonyl into the cobalt-hydride bond. The unique coordination environment of the cobalt ion ligated by oxo-nodes within the porous framework and the rate independency on the pressure of H2 allow the deoxygenation reactions chemoselectively under ambient hydrogen pressure.
Deoxygenation of tertiary and secondary alcohols with sodium borohydride, trimethylsilyl chloride, and potassium iodide in acetonitrile
Kato, Yuichi,Inoue, Tomoka,Furuyama, Yuuki,Ohgane, Kenji,Sadaie, Mahito,Kuramochi, Kouji
supporting information, (2021/11/16)
The deoxygenation of tertiary and secondary alcohols to give the corresponding alkanes is conventionally performed using an organosilane and a strong acid. In this study, a deoxygenation method was developed for tertiary and secondary alcohols, using trimethylsilane and trimethylsilyl iodide generated in situ from sodium borohydride and trimethylsilyl chloride, and trimethylsilyl chloride and potassium iodide, respectively. With our method, tertiary and secondary alcohols, which provided stable carbocations, were converted into the corresponding alkanes. This paper also presents the optimization of the reaction conditions, the reaction mechanism, as well as the scope and limitations of the method.
