A practical method for the synthesis of 6-aroyl phenanthridine derivatives by Fe-catalyzed oxidative radical cyclization of 2-isocyanobiphenyls with benzylic alcohols is described. In addition, this ...cyclization could be occurred by using toluene as aroyl source. The procedure tolerates various functional groups under simple conditions. A single-electron-transfer pathway is proposed according to mechanistic studies.
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Forming heterojunctions and surface coordination of donor molecule (NMI) raises the energy levels of the bands of Cu-Cu2O/rGO-NH2 materials and create an internal electric field. Consequently, both ...O2 activation and electron transfer between the catalyst and the reactants are accelerated in the catalysis of benzylic alcohols.
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•Heterojunctions are formed between the components in semiconductor materials of Cu-Cu2O/rGO-NH2.•The formation of the heterojunctions leads to changes in band structure and creation of IEF.•The ratio of Cu/Cu2O of the materials profoundly affect the rising of their VBM energy levels.•Raising the VBM energy level is beneficial to O2 activation and the IEF accelerates the electron transfer in the catalysis.
In this work, three materials of Cu-Cu2O/rGO-NH2-4.4/1, -1/1 and -1/10.4, in which the numeric suffices denote the ratio of Cu/Cu2O in the materials, were described and characterized using various analytical techniques including FTIR, XRD, SEM, HRTEM, XPS and Raman spectroscopy. To probe the band structures of these materials, UPS, cyclic voltammetry, and UV–vis reflection spectroscopy were also employed. The formation of heterojunctions in the ternary materials tune their band structures by raising the energy level of valence band maximums (VBMs), inducing an internal electric field (IEF) and an electron accumulation layer (EAL) within the materials. Augment of copper content in the materials can enhance the energy level rising. The coordination of N-methylimidazole (NMI) with Cu2O of the materials can also contribute to raising the energy level. The changes in these electronic properties bring about a synergistic effect in selective aerobic oxidation of benzylic alcohols via improving O2 activation and facilitation of electron transfer between the catalyst and the reactants due to the rising of the energy level of VBM and the formation of IEF.
1,2‐Addition reactions using organoboron compounds are one of the useful syntheses of various functionalized alcohols, but they generally require a large quantity of bases. In this study, we ...attempted to solve this problem by synthesizing unsymmetrical 1,3‐diarylimidazoline‐type N‐heterocyclic carbene (NHC)‐coordinated C^C* cyclometalated palladium(II) complexes with bridging hydroxide ligands (CYPOHs) in two steps and one pot from the corresponding Cl bridged dimer and using them as catalysts. 2,6‐di(pentan‐3‐yl)aniline (IPent)‐based NHC coordinated PhS‐IPent‐CYPOH acted as a highly efficient catalyst for the 1,2‐addition of (hetero)arylboronates to a large number of aldehydes and ketones, including unactivated ketones, under base‐free conditions.
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A simple rhodium-catalyzed addition reaction of aldehydes with arylboronic acids in aqueous γ-valerolactone provides the corresponding benzylic alcohols in moderate to good yields. ...Other organoboron reagents (boronic esters, aryl-trifluoroborates, etc.) also showed good compatibilities, albeit with relatively lower yields.
Main observation and conclusion
We report an exclusively tandem C—O and C—C bond forming beyond the esterification and cyclization reaction of 2‐acylbenzoic acids with alcohols to regio‐ and ...stereoselective synthesis of the (Z)‐3‐ylidenephthalides. The reaction uses the nontoxic, inexpensive H3PMo12O40 as catalyst and produces water as the sole by‐product, making the reaction environmentally benign and sustainable. Moreover, this reaction features an eco‐friendly reaction condition, facile scalability, and easy derivatization of the products to drugs and bioactive compounds. The mechanism studies and density functional theory calculations reveal that the appropriate acid catalyst is the key to the selectivity of this transformation.
A regio‐ and stereoselective synthesis of (Z)‐3‐ylidenephthalides via H3PMo12O40‐catalyzed cyclization of 2‐acylbenzoic acids with benzylic alcohols was developed.
A mild and efficient approach for the electrochemical conversion of benzyl alcohols to benzaldehydes is reported in homogeneous medium using Carbon/Stainless Steel electrodes and NaCl as mediator ...with H
2
SO
4
as supporting electrolyte. To achieve excellent product conversion, optimization of the reaction condition with various parameters was carried out in a beaker type cell. In 2 F of current density and ambient temperature, benzyl alcohols electrochemically oxidized to benzaldehydes in 90% yield. The present work demonstrates a green and sustainable route for benzaldehydes preparation and the superiority of electrochemical method for organic synthesis.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Directed evolution is a powerful tool for developing biocatalysts with tailor-made properties for biocatalytic applications. High-throughput activity screening of large mutant libraries generated by ...e.g. means of directed evolution is usually performed in 96-well microtiter plates requiring, however, time-consuming and laborious enzyme expression, cell harvesting and activity measurements. In addition, automated liquid handling systems are needed to cope with the high number of colonies to be screened. Herein, we developed an agar plate-based assay for simple and fast screening of H2O2-producing aryl-alcohol oxidase (AAO) mutant libraries in Pichia pastoris. Buffered minimal methanol agar plates were supplemented with 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), horseradish peroxidase (HRP) and the target substrate. AAO activity is visualized by formation of green zones around AAO-secreting P. pastoris colonies due to ABTS oxidation by HRP which is fueled with H2O2 by AAO in course of substrate oxidation. Colonies were screened within 24 h for AAO activity using different AAO substrates like veratryl alcohol, p-anisyl alcohol or trans,trans-2,4-hexadien-1-ol and even low AAO activity towards 5-hydroxymethylfurfural could be detected within 48 h. The developed agar plate-based assay can be extended to other substrates and might also be applied for fast and substrate-specific screening of other H2O2-producing oxidases in P. pastoris.
•AAO activity screening on HRP/ABTS-agar plates using Pichia pastoris as host.•Assay can be used for screening towards a broad range of AAO substrates.•Fast screening of AAO libraries in P. pastoris for improved activity or expression.•Transferable to other H2O2-producing oxidases heterologously expressed in Pichia.
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•In this paper, two transition metal oxide nanoparticles are synthesized and characterized by XRD, UVD FT-IR and SEM.•Actually, we were studied influence of Cu metal doped on ZnO ...catalytic activity.•The catalytic performance of ZnO is significantly enhanced by doped Cu metal on nano ZnO.•Benzylic alcohols converted to corresponding aldehyde or ketone by nano CuZnO with H2O2 under room temperature and solvent free for 3h.
Nano-mushroom ZnO and Cu-doped ZnO were prepared by co-precipitation method and characterized by general techniques. The particle size of ZnO is 28nm, while it decreased to 17nm by doping Cu2+ ion on it.
Then, catalytic properties of these nanoparticles were studied in oxidation of benzylic alcohols by 30% H2O2 with nano-catalyst at room temperature. The results showed, a solvent free, green, selective, high yield and effective oxidation. Also, the catalytic performance such as: % conversion, % selectivity and rate of reaction of ZnO are significantly enhanced by doped 1% Cu metal cation on nano ZnO. The ketone and aldehyde are the main product of secondary and primary benzylic alcohols respectively under this condition.
This work demonstrates an efficient method to prepare α-aryl nitriles by direct cyanation of benzylic alcohol with TMSCN in the presence of a catalytic amount of Zn(OTf)2 under heating condition. A ...variety of benzylic alcohols can be converted into the corresponding α-aryl nitriles in good to excellent yields.
Cu-based alloys catalyse selective aerobic oxidation of benzylic alcohols via their thin layers of surface oxides under mild conditions. The catalytic activity of Cu2O can be tuned by the work ...functions (ϕ) of both the solute metals and their oxides, of which the work functions of the oxides possess much more profound influence on the catalysis.
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•Heterojunctions are formed between copper alloys and the thin layers of surface oxides and within the surface oxides layers.•At the thin layer of the surface oxides, the catalysis of aerobic oxidation of benzylic alcohols occurs.•The catalytic activity of the copper alloys varies with the solute metals.•The work functions of both the solute metals and their oxides can electronically tune the catalysis.•The work functions of the surface oxides influence the catalysis far more profoundly than those of the solute metals.
In this work, four types of commercially available copper-based alloys, Cu-Ni-Zn, Cu-Zn, Cu-Pb-Sn and Cu-Sn were examined for their catalysis on selective aerobic oxidation of benzylic alcohols at 60 °C with N-methylimidazole (NMI) and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) as the co-catalysts in acetonitrile. It has been found that these solute metals exhibit various influences on the catalysis and such influences correlate to the work-functions of the solute metals and their surface oxides. The solute metals and their oxides of lower work functions (Sn and Zn) than Cu and Cu2O, respectively, can enhance the catalysis whereas Ni and NiO which possess quite larger work functions almost entirely jeopardize the catalysis. The electronic effect is conveyed through a three-ply structure, the bulky part of the alloy particles, Motty-Schottky junction and the surface oxides, of which the surface oxides affect much more profoundly the catalysis than the other two. The electronic effect is attributed to the band structure and internal electric field within the alloys caused by Fermi energy level alignment due to the difference in their work functions between Cu/Cu2O and M/MO (M = Sn, Zn, Pb and Ni). Moreover, the alloys exhibit much improved durability compared to either Cu or Cu2O, respectively.
