90-00-6Relevant academic research and scientific papers
Designer Outer Membrane Protein Facilitates Uptake of Decoy Molecules into a Cytochrome P450BM3-Based Whole-Cell Biocatalyst
Karasawa, Masayuki,Shoji, Osami,Stanfield, Joshua Kyle,Suzuki, Kazuto,Yonemura, Kai
supporting information, (2021/12/16)
We report an OmpF loop deletion mutant, which improves the cellular uptake of external additives into an Escherichia coli whole-cell biocatalyst. Through co-expression of the OmpF mutant with wild-type P450BM3 in the presence of decoy molecules, the yield
A mild and practical method for deprotection of aryl methyl/benzyl/allyl ethers with HPPh2andtBuOK
Pan, Wenjing,Li, Chenchen,Zhu, Haoyin,Li, Fangfang,Li, Tao,Zhao, Wanxiang
, p. 7633 - 7640 (2021/09/22)
A general method for the demethylation, debenzylation, and deallylation of aryl ethers using HPPh2andtBuOK is reported. The reaction features mild and metal-free reaction conditions, broad substrate scope, good functional group compatibility, and high chemical selectivity towards aryl ethers over aliphatic structures. Notably, this approach is competent to selectively deprotect the allyl or benzyl group, making it a general and practical method in organic synthesis.
Aromatic C?H Hydroxylation Reactions with Hydrogen Peroxide Catalyzed by Bulky Manganese Complexes
Masferrer-Rius, Eduard,Borrell, Margarida,Lutz, Martin,Costas, Miquel,Klein Gebbink, Robertus J. M.
, p. 3783 - 3795 (2021/03/09)
The oxidation of aromatic substrates to phenols with H2O2 as a benign oxidant remains an ongoing challenge in synthetic chemistry. Herein, we successfully achieved to catalyze aromatic C?H bond oxidations using a series of biologically inspired manganese catalysts in fluorinated alcohol solvents. While introduction of bulky substituents into the ligand structure of the catalyst favors aromatic C?H oxidations in alkylbenzenes, oxidation occurs at the benzylic position with ligands bearing electron-rich substituents. Therefore, the nature of the ligand is key in controlling the chemoselectivity of these Mn-catalyzed C?H oxidations. We show that introduction of bulky groups into the ligand prevents catalyst inhibition through phenolate-binding, consequently providing higher catalytic turnover numbers for phenol formation. Furthermore, employing halogenated carboxylic acids in the presence of bulky catalysts provides enhanced catalytic activities, which can be attributed to their low pKa values that reduces catalyst inhibition by phenolate protonation as well as to their electron-withdrawing character that makes the manganese oxo species a more electrophilic oxidant. Moreover, to the best of our knowledge, the new system can accomplish the oxidation of alkylbenzenes with the highest yields so far reported for homogeneous arene hydroxylation catalysts. Overall our data provide a proof-of-concept of how Mn(II)/H2O2/RCO2H oxidation systems are easily tunable by means of the solvent, carboxylic acid additive, and steric demand of the ligand. The chemo- and site-selectivity patterns of the current system, a negligible KIE, the observation of an NIH-shift, and the effectiveness of using tBuOOH as oxidant overall suggest that hydroxylation of aromatic C?H bonds proceeds through a metal-based mechanism, with no significant involvement of hydroxyl radicals, and via an arene oxide intermediate. (Figure presented.).
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 (2021/02/09)
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.
Insight into the chemoselective aromatic: Vs. side-chain hydroxylation of alkylaromatics with H2O2catalyzed by a non-heme imine-based iron complex
Ticconi, Barbara,Capocasa, Giorgio,Cerrato, Andrea,Di Stefano, Stefano,Lapi, Andrea,Marincioni, Beatrice,Olivo, Giorgio,Lanzalunga, Osvaldo
, p. 171 - 178 (2021/01/28)
The oxidation of a series of alkylaromatic compounds with H2O2 catalyzed by an imine-based non-heme iron complex prepared in situ by reaction of 2-picolylaldehyde, 2-picolylamine, and Fe(OTf)2 in a 2?:?2?:?1 ratio leads to a marked chemoselectivity for aromatic ring hydroxylation over side-chain oxidation. This selectivity is herein investigated in detail. Side-chain/ring oxygenated product ratio was found to increase upon decreasing the bond dissociation energy (BDE) of the benzylic C-H bond in line with expectation. Evidence for competitive reactions leading either to aromatic hydroxylation via electrophilic aromatic substitution or side-chain oxidation via benzylic hydrogen atom abstraction, promoted by a metal-based oxidant, has been provided by kinetic isotope effect analysis. This journal is
CATALYTIC FUNNELING OF PHENOLICS
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Paragraph 0035; 0089-0090; 0169, (2021/04/30)
In general, present invention concerns an integrated wood-to-xylochemicals biorefinery, enabling production of renewable phenol, phenolic oligomers, propylene, and carbohydrate pulp from lignocellulosic biomass.
Preparation of NiCu Alloy Catalyst for the Hydrodeoxygenation of Benzofuran
Zhu, Tianhan,Song, Hua,Li, Feng,Chen, Yanguang
, p. 1670 - 1682 (2020/10/21)
A series of bimetallic NixCu(10-x)/SiO2 (where x is the mass fraction of Ni and the total metal loading was fixed at 10 wt%.) catalysts with different Ni/Cu mass ratio are prepared and characterized by X-Ray diffraction (XRD), N2 adsorption-desorption, inductively coupled plasma mass spectrometry (ICP-MS), H2 temperature-programmed reduction (H2-TPR) and transmission electron microscope (TEM). The benzofuran (BF) hydrodeoxygenation (HDO) performance of as-prepared catalysts are evaluated in a fixed flow reactor. The results showed that the incorporation of Cu to Ni/SiO2 catalyst can increase surface area of catalyst and improve the reducibility of nickel oxide species, which contributed to higher catalytic activity and total deoxygenated compounds yield. Moreover, the strong synergistic effect between Ni and Cu led to the formation of NiCu alloy at the Ni mass fraction of 5 wt% and thus induced smaller crystallite size and exposure of more active particles, which inevitably contributed to the improved HDO performance for Ni5Cu5/SiO2 catalyst. At 300 °C, 3.0 MPa, MHSV=3.0 h?1 and H2/oil = 500(v/v), the total yield of deoxygenated products over Ni5Cu5/SiO2 catalyst reached 86.0%, which is increased by 10.8% and 77.4% as compared to those of monometallic Ni/SiO2 (75.2%) and Cu/SiO2 catalysts (8.8%), respectively. Finally, a possible reaction network for HDO of BF on Ni5Cu5/SiO2 catalyst was proposed. Graphic Abstract: [Figure not available: see fulltext.]
Synthesis of Highly Substituted Phenols and Benzenes with Complete Regiochemical Control
Zhang, Xiaojie,Beaudry, Christopher M.
supporting information, p. 6086 - 6090 (2020/08/12)
Substituted phenols are requisite molecules for human health, agriculture, and diverse synthetic materials. We report a chemical synthesis of phenols, including penta-substituted phenols, that accommodates programmable substitution at any position. This method uses a one-step conversion of readily available hydroxypyrone and nitroalkene starting materials to give phenols with complete regiochemical control and in high chemical yield. Additionally, the phenols can be converted into highly and even fully substituted benzenes.
Synthesis of Ni2P/Al2O3 utilizing triphenylphosphine (TPP) as the phosphorus source for hydrodeoxygenation of benzofuran
Jiang, Bolong,Jiang, Nan,Han, Chunbao
, p. 7577 - 7582 (2020/06/19)
A novel route to synthesize highly active Ni2P/Al2O3 (TPP) utilizing triphenylphosphine (TPP) as the phosphorus source at a low temperature of 573 K is described. The as-prepared catalysts were characterized by X-ray diffraction (XRD), CO uptake, Brunner-Emmett-Teller (BET) measurements, and X-ray photoelectron spectroscopy (XPS). The catalytic activity of the Ni2P/Al2O3 (TPP) catalyst and the role of the TPP phosphorus source were studied using hydrodeoxygenation (HDO) of benzofuran (BF) as a probe reaction. The results show that the use of TPP as the phosphorus source could suppress the strong interaction between phosphate and Al2O3, thereby the formation of AlPO4 was avoided. As compared to the Ni2P/Al2O3 prepared by using (NH4)2HPO4 as the phosphorus source, Ni2P/Al2O3 (TPP) possessed significantly higher surface area and smaller Ni2P particle size. The HDO activity and yield of O-free products over the Ni2P/Al2O3 (TPP) catalyst were increased by 17.2% and 36.0%, respectively, when compared with those found for Ni2P/Al2O3 prepared using (NH4)2HPO4. The use of TPP as the phosphorus source could effectively promote the dehydration of 2-ethylphenol (2-EtPh) to form ethylbenzene (EB), and the demethylation of ethylcyclohexane (ECH) to methylcyclohexane (MCH).
Guaiacol demethoxylation catalyzed by Re2O7 in ethanol
Yan, Fei,Sang, Yushuai,Bai, Yunfei,Wu, Kai,Cui, Kai,Wen, Zhe,Mai, Fuhang,Ma, Zewei,Yu, Linhao,Chen, Hong,Li, Yongdan
, p. 231 - 237 (2019/08/12)
Re2O7 is used to convert guaiacol in alcohols at 280–320 °C. In ethanol, guaiacol is deoxygenated and alkylated, and the major products are phenol and alkylphenols (including ethylphenol, diethylphenol, diisopropylphenol, di-tert-butylphenol and 2,6-di-tert-butyl-4-ethylphenol), accounting for 97 mol% of all products after 6 hour reaction at 320 °C. Both catechol and phenol are the intermediates of guaiacol demethoxylation. Among the substituents, ethyl is directly provided by ethanol while isopropyl and tert-butyl are formed by the addition of methyl to ethyl step by step. In addition, Re2O7 has negligible activity for the saturation of benzene ring so it does not cause considerable over-consumption of reductant. The actual catalyst for guaiacol demethoxylation is likely a ReIV?VI species.
