cas 123-08-0, 4-Hydroxybenzaldehyde | Articles data

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Brady,Jakobovits
p. 767,769, 777
(1950)
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Selective synthesis of p-hydroxybenzaldehyde by liquid-phase catalytic oxidation of p-cresol
Liquid-phase oxidation of p-cresol over insoluble cobalt oxide (Co 3O4) catalyst under elevated pressure of air gave 95% selectivity to p-hydroxybenzaldehyde, an important flavoring intermediate. The selectivity to p-hydroxybenzaldehyde could be enhanced by manipulating the concentrations of p-cresol, sodium hydroxide, and catalyst and the partial pressure of oxygen in such a way that the byproducts normally encountered in this oxidation process were eliminated or minimized significantly.
Rode, Chandrashekhar V.,Sonar, Mahesh V.,Nadgeri, Jayprakash M.,Chaudhari, Raghunath V.
p. 873 - 878
(2004)
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Practical process for the air oxidation of cresols: Part B. evaluation of the laboratory-scale oxidation process
Mechanistic proposals and predictions made in a preceding paper (Part A) were evaluated by carrying out the catalytic air oxidation of p-cresol in an alternative solvent system, comprising either a mixture of ethylene glycol and acetic acid (for oxidations under acidic conditions) or ethylene glycol and water (for oxidations under basic conditions). The results obtained in these experiments confirmed that ethylene glycol acts as a nucleophile in these solvent systems, thereby stabilizing the quinomethide intermediate and resulting in highly efficient oxidations in both alkaline and acidic media. 4-Hydroxybenzaldehyde, the desired product, was thus obtained in isolated yields of up to 98% and purities >99%. The inherent draw-backs associated with alkaline methanol and aqueous acetic acid solutions were thus circumvented, and the result is a highly efficient process for the production of 4-hydroxybenzaldehyde.
Barton, Benita,Logie, Catherine G.,Schoonees, Barbara M.,Zeelie, Bernard
p. 70 - 79
(2005)
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Synthesis of Copolymers of N-Vinylpyrrolidone with Crotonic Acid Modified with 4-Oxybenzaldehyde
Radical copolymerization of N-vinylpyrrolidone with crotonic acid in 2-propanol has afforded water-soluble products, which have been characterized in terms of composition as well as molecular and hydrodynamic parameters. The obtained copolymers have been modified with 4-oxybenzaldehyde. Structures of the products of the polymer analogous reaction, potential carriers of several bioactive substances, have been confirmed using elemental and functional analysis and spectroscopic data.
Solovskii,Borisenko,Tarabukina,Amirova
p. 514 - 519
(2018)
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A novel practical cleavage of tert-butyl esters and carbonates using fluorinated alcohols
Thermolytic cleavage of t-butyl esters and t-butyl carbonates was accomplished using TFE (2,2,2-trifluoroethanol) or HFIP (hexafluoroisopropanol) as solvent. Thus, a practical method to cleanly convert t-butyl esters and carbonates into the corresponding carboxylic acids, decarboxylated products, or alcohols in nearly quantitative yields was developed. The product is recovered by a simple solvent evaporation. The practicality of this methodology was demonstrated on alkyl, aryl, and heteroaromatic esters.
Choy, Jason,Jaime-Figueroa, Saul,Lara-Jaime, Teresa
p. 2244 - 2246
(2010)
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Increased para Selectivity in the Reimer-Tiemann Reaction by Use of Polyethylene Glycol as Complexing Agent
The para selectivity of the Reimer-Tiemann reaction was increased by use of polyethylene glycol in the reaction medium.The polyethylene glycol complexes the phenolate substrate masking the ortho position of the benzene nucleus increasing para selectivity without affecting the total yield.
Neumann, Ronny,Sasson, Yoel
p. 569 - 570
(1986)
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Novel and efficient oxidation of benzyl ethers to benzaldehydes by DMSO/49% aq. HBr
Dimethylsulfoxide (DMSO) oxidizes benzyl ethers into corresponding benzaldehydes at 110°C; the reaction is accelerated by 49% aq. HBr. The conditions work well for different aryl-substituted benzyl ethers. This protocol is inert toward dialkyl ethers. Copyright Taylor & Francis Group, LLC.
Naik, Ramesh,Pasha
p. 1723 - 1726
(2007)
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Total synthesis of the proposed structures of gladiosides I and II
Burkholderia gladioli is a Gram-negative bacterium that biosynthesizes a cocktail of potent antimicrobial compounds, including the antifungal phenolic glycoside sinapigladioside. Herein, we report the total synthesis of the proposed structures of gladiosides I and II, two structurally related phenolic glycosides previously isolated from B. gladioli OR1 cultures. Importantly, the physical and analytical data of the synthetic compounds were in significant discrepancies with the natural products suggesting a misassignment of the originally proposed structures. Furthermore, we have uncovered an acid-catalyzed fragmentation mechanism converting the α,β-unsaturated methyl carbamate-containing gladioside II into the aldehyde-containing gladioside I. Our results lay the foundation for the expeditious synthesis of derivatives of these Burkholderia-derived phenolic glycosides, which would enable to decipher their biological roles and potential pharmacological properties.
Hussain, Nazar,Delar, Emmanilo,Piochon, Marianne,Groleau, Marie-Christine,Tebbji, Faiza,Sellam, Adnane,Déziel, Eric,Gauthier, Charles
(2021)
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Aqueous selective photocatalytic oxidation of salicyl alcohol by TiO2 catalysts: Influence of some physico-chemical features
Partial photocatalytic oxidation of salicyl alcohol (2-hydroxybenzyl alcohol) to salicylaldehyde in water was investigated under environmental friendly conditions in the presence of home-prepared and commercial TiO2 (Merck and Aeroxide P25) samples under UVA irradiation. The photocatalysts were characterized by using BET, XRD, SEM and/or TEM techniques. The effects of crystallinity degree, pH (3–11) and presence of a hole trap (ethanol) on the photocatalytic activity and product selectivity were investigated. 4-Hydroxybenzyl alcohol was also used to study the influence of the position of the substituent group in the aromatic ring. High alcohols conversion and product selectivity values were obtained at pH = 11 by using well crystallized TiO2 samples. The conversion values significantly decreased by increasing the hole trap concentration, whereas the selectivity values increased slightly. The selectivity towards the corresponding aldehyde after 30% of alcohol conversion was significantly higher for 4-HBA (48%) than for 2-HBA (32%), due to the role of the para position of the substituent group. In order to clarify the different selectivity of the products, various experiments have been also performed starting from the products; these results indicate that the selectivity is also strongly dependent on the stability of the formed products under the experimental conditions used. By concluding, this article reports that the conversion and selectivity values for the studied reaction depend both on the TiO2 type and on the substrate.
Yurdakal, Sedat,Bellardita, Marianna,Pibiri, Ivana,Palmisano, Leonardo,Loddo, Vittorio
p. 16 - 24
(2021)
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Iron-Catalyzed Synthesis of the Hexahydrocyclopenta[c]furan Core and Concise Total Synthesis of Polyflavanostilbene B
The first synthesis of polyflavanostilbene B (1), which has seven contiguous stereocenters including two quaternary carbon centers, from abundant polymeric (?)-epicatechin gallate on a gram scale in three steps without the use of protecting groups is reported. The key transformations of this strategy include a regioselective and stereoselective substitution of resveratrol to give the 4-derivative of (?)-epicatechin 3-gallate and an iron-catalyzed cyclization reaction. The possible radical cyclization mechanism in the formation of the hexahydrocyclopenta[c]furan core is also discussed.
Wang, Xujie,Liu, Fu,Yun, Juping,Feng, Ziming,Jiang, Jianshuang,Yang, Yanan,Zhang, Peicheng
p. 10127 - 10131
(2018)
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Oxidation of p-cresol to p-hydroxybenzaldehyde with molecular oxygen in the presence of CuMn-oxide heterogeneous catalyst
A high-yield synthesis of p-hydroxybenzaldehyde from p-cresol and molecular oxygen was achieved over a CuMn-oxide supported carbon catalyst. The reaction parameters such as pressure, stirring speed, reaction temperature, solvent, and the amount of sodium hydroxide in the reaction media were optimized. As a result, a high conversion of p-cresol (99%) and a high selectivity to p-hydroxybenzaldehyde (96%) were realized at the same time. Catalyst separation and recycling tests clearly showed that the reaction proceeded on the heterogeneous catalyst but not on dissolved species.
Wang, Feng,Yang, Guanyu,Zhang, Wei,Wu, Wenhai,Xu, Jie
p. 633 - 638
(2004)
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Antioxidant-Inspired Drug Discovery: Antitumor Metabolite Is Formed in Situ from a Hydroxycinnamic Acid Derivative upon Free-Radical Scavenging
Cancer cells generally possess higher levels of reactive oxygen species than normal cells, and this can serve as a possible therapeutic target. In this proof-of-concept study, an antioxidant-inspired drug discovery strategy was evaluated using a hydroxycinnamic acid derivative. The processing of oxidized mixtures of p-coumaric acid methyl ester (pcm) revealed a new antitumor lead, graviquinone. Graviquinone bypassed ABCB1-mediated resistance, induced DNA damage in lung carcinoma cells but exerted DNA protective activity in normal keratinocytes, and modulated DNA damage response in MCF-7 cells. The cytotoxic effect of pcm in MCF-7 cells was potentiated under H2O2-induced oxidative stress, and the formation of graviquinone was confirmed by Fenton's reaction on pcm. In silico density functional theory calculations suggested graviquinone as a kinetic product of pcm-scavenging ?OH radicals. Our results demonstrate the pharmacological value of an in situ-formed, oxidative stress-related metabolite of an antioxidant. This might be of particular importance for designing new strategies for antioxidant-based drug discovery.
Fási, Laura,Di Meo, Florent,Kuo, Ching-Ying,Stojkovic Buric, Sonja,Martins, Ana,Kúsz, Norbert,Béni, Zoltán,Dékány, Miklós,Balogh, Gy?rgy Tibor,Pesic, Milica,Wang, Hui-Chun,Trouillas, Patrick,Hunyadi, Attila
p. 1657 - 1668
(2019)
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Highly active nanostructured Co3O4 catalyst with tunable selectivity for liquid phase air oxidation of p-cresol
This is a first report of highly efficient heterogeneous nanostructured Co3O4 catalyst (6-8 nm) having high surface area (95 m2/g) developed for selective liquid phase air oxidation of p7-cresol under atmospheric pressure conditions. Copyright
Kshirsagar, Vikas S.,Vijayanand, Subramanian,Potdar, Hari S.,Joy, Pattayil A.,Patil, Kashinath R.,Rode, Chandrashekhar V.
p. 310 - 311
(2008)
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Enzymatic oxidative coupling of hydroxyphenylglycine derivatives
In contrast to N-protected tyrosine derivatives, N-protected hydroxy-D- phenylglycine derivatives underwent decarboxylation to give 4- hydroxybenzaldehyde under the normal incubation conditions. When both the carboxyl and amino groups of hydroxy-D-phenylglycine are blocked, the C-C and C-O coupling products were obtained in 48% and 32% yields respectively. No racemization of the chiral center was observed for all the substrates examined.
Guo, Zhi-Wei,Machiya, Koji,Ma, You-An,Sih, Charles J.
p. 5679 - 5682
(1998)
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Reduced Graphene Oxide Composite with Oxidizable Manganese/Cobalt Mixed Oxide for p-Cresol Oxidation by Using Molecular Oxygen
A composite of graphene oxide (GO) with mixed oxide (MnCo) was prepared by using a solvothermal method. During the synthesis, both the reduction of GO and growth of metal oxides took place simultaneously. The as-prepared composite material was highly selective for the liquid-phase oxidation of p-cresol to form p-hydroxybenzaldehyde in 71% yield within 1 h. The composite material was characterised by SEM, X-ray photoelectron spectroscopy, high-resolution TEM and cyclic voltammetry (CV). A CV study revealed that the increase in the redox potential of the mixed oxide after being supported on GO, led to its higher activity of the catalyst for the oxidation reaction. The stability of the catalyst under the reaction conditions was studied by its successful reuse in three cycles.
Jha, Ajay,Patil, Sagar H.,Solanki, Bhanu P.,Ribeiro, Ana P. C.,Castro, Carlos A. N.,Patil, Kashinath R.,Coronas, Alberto,Rode, Chandrashekhar V.
p. 1164 - 1169
(2015)
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Specific Catalysis by α-Cyclodextrin on the Dichlorocarbene Attack at Phenolate
A selsctive attack of dichlorocarbene at the para-position of the phenolate has been achieved by using α-cyclodextrin and the reaction mechanism has been studied by the 13C-NMR and 1H-NMR spectroscopy.The attack of the carbene at the para-position of phenolate (82percent) is dominant over the attack at the ortho-position (18percent) in the presence of 0.15 mol dm-3 of α-cyclodextrin, which is in contrast with the predominance of the ortho-attack (59percent) over the para-attack (41percent) in the absence of α-cyclodextrin.
Komiyama, Makoto,Hirai, Hidefumi
p. 2053 - 2056
(1981)
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Amakasu,T.,Sato,K.
p. 1428 - 1432
(1967)
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FORMATION OF p-HYDROXYBENZOIC ACID FROM p-COUMARIC ACID BY CELL FREE EXTRACT OF LITHOSPERMUM ERYTHRORHIZON CELL CULTURES
The enzymatic formation of p-hydroxybenzoic acid from p-coumaric acid has been detected in cell free extracts of Lithospermum erythrorhizon cell cultures.In the absence of NAD, p-hydroxybenzaldehyde is formed instead of p-hydroxybenzoic acid.The reaction is specific to p-coumaric acid.In addition, a p-hydroxybenzaldehyde dehydrogenase activity is also found.The results suggest that the reaction mechanism is non-oxidative.Key Word Index - Lithospermum erythrorhizon; Boraginaceae; cell culture;biosynthesis; p-hydroxybenzoic acid; p-coumaric acid; p-hydroxybenzaldehyde; shikonin.
Yazaki, Kazufumi,Heide, Lutz,Tabata, Mamoru
p. 2233 - 2236
(1991)
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Novel synthesis of Ag decorated TiO2 anchored on zeolites derived from coal fly ash for the photodegradation of bisphenol-A
The disposal of millions of tons of coal fly ash (CFA) threatens the environment, hence means to reuse CFA are highly sought after. In this study, CFA was reused to make materials which were tested for water purification. Zeolitic material (CFA-Zeo) was derived from CFA by a 2-step alkali-fusion hydrothermal method and then composited with TiO2 nanoparticles using a novel resin-gel technique. CFA-Zeo loadings were 15 and 30 wt% in the resulting TiO2/CFA-Zeo composites. These composites were then loaded with 1 wt% Ag nanoparticles by a deposition-precipitation technique using NaOH and urea. CFA-Zeo rods (morphology confirmed by TEM) were confirmed by PXRD to be sodium aluminum silicate hydrate. TEM analyses of the CFA-Zeo rods in the composites revealed them to be completely coated with TiO2 nanoparticles that had Ag nanoparticles on their surfaces. The photoluminescence emission peak of TiO2 was found to be significantly higher than that of TiO2/CFA-Zeo composites, with the TiO2/CFA-Zeo composites that were loaded with Ag having even lower emission intensities. UV-vis DRS spectra showed that CFA-Zeo had no effect on the band gap of TiO2, while composites that contained Ag had a wide absorption band in the visible region. The photocatalytic efficiency of these materials was then determined using bisphenol-A (BPA) as a model compound under both UV and visible light. Except for the 30 wt% TiO2/CFA-Zeo composites without Ag, all of the composites had superior photoactivity to uncomposited TiO2 under both UV and visible light. On the other hand, composites with Ag nanoparticles showed the best photoactivities. The superior photoactivities of these composites under UV-light were mainly attributed to the separation of charge carriers, whereas under visible light it was attributed to the ability of silver to harvest visible light through surface plasmon resonance (SPR).
Hlekelele, Lerato,Franklyn, Paul J.,Dziike, Farai,Durbach, Shane H.
p. 1902 - 1912
(2018)
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Halicloic acids A and B isolated from the marine sponge Haliclona sp. collected in the Philippines inhibit indoleamine 2,3-dioxygenase
Two new merohexaprenoids, halicloic acids A (1) and B (2), have been isolated from the marine sponge Haliclona (Halichoclona) sp. collected in the Philippines. The glycolic acids 1 and 2 slowly decomposed during acquisition of NMR data to aldehydes 3 and 4, respectively, via an oxidative decarboxylation. Halicloic acid B (2) has the new rearranged "haliclane" meroterpenoid carbon skeleton. The halicloic acids 1 and 2 are indoleamine 2,3-dioxygenase inhibitors that are significantly more active than the decomposition products 3 and 4.
Williams, David E.,Steino, Anne,De Voogd, Nicole J.,Mauk, A. Grant,Andersen, Raymond J.
p. 1451 - 1458
(2012)
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Kratzl,Billek
p. 845,854
(1954)
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Selective oxidation of aromatic hydrocarbons by potassium and phosphorous-modified iron oxide-silica nanocomposite
Supported iron catalysts are active for hydrocarbon oxidation with H 2O2, but the hydrogen peroxide dismutation is a shortcoming that may constrain their applications. Herein, we attempted to address this problem using potassium and phosphate-doped iron oxide-silica nanocomposite (KPFeSi) synthesized via sol-gel methods. The promoted silica-iron oxide nanocomposite has been characterized by elemental analyses, FTIR, X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) surface-size determination. The synthesized KPFeSi was an active catalyst in the low-temperature liquid phase oxidation of various alkyl aromatics with hydrogen peroxide in conversions of 31-78%. Furthermore, the direct oxidation of benzene into phenol using hydrogen peroxide has been achieved in the absence of any acid with this KPFeSi compound. Springer Science+Business Media B.V. 2011.
Masoudian, Shahla,Monfared, Hassan Hosseini
p. 37 - 43
(2012)
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Photochromism of the synthetic 4′,7-dihydroxyflavylium chloride
The synthetic compound 4′,7-dihydroxyflavylium chloride shows an interesting photochromic effect at moderately acidic pH values. Pale yellow solutions of this compound, equilibrated in the dark at pH 3.4, become bright yellow upon irradiation with 313-nm light. Switching off the light, gives back the initial pale yellow solution. Photochemical methods, 1H NMR, and molecular orbital calculations were used to elucidate this photochromic behavior. In solutions equilibrated in the dark (pH 5.7), the existence of two main species in equilibrium is demonstrated: the colored flavylium cation and the colorless trans-chalcone. Freshly prepared solutions of this compound at pH 6.2 reveal the existence of another colored form, the quinonoidal base, which reacts thermally to yield trans-chalcone. An analogous reaction takes place in freshly prepared solutions at pH 3.4: the flavylium cation is partially converted into trans-chalcone. The extent of such conversion is pH dependent and nearly complete at pH 6.2. Irradiation of transchalcone at the wavelength of 313 nm partially gives back the initial colored form, with concomitant formation of small amounts of photodegradation products. The turnover of the photochromic reaction is greater at pH 3.4 than at pH 6.2. The photochromism is explained on the basis of a trans-cis photoisomerization. In fact the relative stability of the two chalcone isomers is reversed in the excited state, as predicted from molecular orbital calculations.
Figueiredo, Paulo,Lima, Jo?o C.,Santos, Helena,Wigand, Marie-Claude,Brouillard, Raymond,Ma?anita, António L.,Pina, Fernando
p. 1249 - 1254
(1994)
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Metal incorporated Horseradish Peroxidase (HRP) catalyzed oxidation of resveratrol: Selective dimerization or decomposition
Horseradish Peroxidase (HRP) is a commercially available and prevalently used peroxidase with no specific substrate binding domain. However, after being incorporated with different metal cations, new catalytic functions were found in biomimetic oxidation of resveratrol. Based on the results of screening, Ca, Cu, Fe and Mn incorporated enzymes showed distinctive effects, either decomposition or dimerization products were observed.
Li, Chang,Xu, Xiaofei,Lu, Jing,Wang, Lin,Pan, Yuanjiang
p. 22976 - 22980
(2013)
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Hodgson,Jenkinson
p. 469,470
(1929)
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BIOSYNTHESIS OF TUBERIN AND XANTHOCILLIN FROM TYROSINE
(2S)-Tyrosine (5) is incorporated stereospecifically into tuberin (1) with retention of the 3-pro-S proton and incomplete retention of the 2-S proton; a parallel pathway to the xanthocillin (4) is apparent with stereospecific retention of the 3-pro-R proton of tyrosine; results of experiments with threo- and erythro-3-hydroxytyrosine in relation to tuberin biosynthesis are reported.
Herbert, Richard B.,Mann, Jonathan
p. 4263 - 4266
(1984)
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A highly stable zeotype mesoporous zirconium metal-organic framework with ultralarge pores
Through topological rationalization, a zeotype mesoporous Zr-containing metal-organic framework (MOF), namely PCN-777, has been designed and synthesized. PCN-777 exhibits the largest cage size of 3.8 nm and the highest pore volume of 2.8 cm3 g-1among reported Zr-MOFs. Moreover, PCN-777 shows excellent stability in aqueous environments, which makes it an ideal candidate as a support to incorporate different functional moieties. Through facile internal surface modification, the interaction between PCN- 777 and different guests can be varied to realize efficient immobilization.
Feng, Dawei,Wang, Kecheng,Liu, Tian-Fu,Park, Jihye,Wei, Zhangwen,Bosch, Mathieu,Zhou, Hong-Cai,Su, Jie,Zou, Xiaodong,Yakovenko, Andrey
p. 149 - 154
(2015)
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Copper and manganese: Two concordant partners in the catalytic oxidation of p-cresol to p-hydroxybenzaldehyde
Copper and manganese were found to be two concordant partners in the synthesis of p-hydroxybenzaldehyde from p-cresol; under mild conditions, this research realised 95.6% selectivity for p-hydroxybenzaldehyde at 98.5% conversion of p-cresol.
Wang, Feng,Yang, Guan-Yu,Zhang, Wei,Wu, Wen-Hai,Xu, Jie
p. 1172 - 1173
(2003)
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PHOTOCATALYTIC OXIDATION OF p-CRESOL IN AQUEOUS TITANUM DIOXIDE SUSPENSION
The reaction products of the photocatalytic oxidation of p-cresol were characterized by high performance liquid chromatography.The influence of p-cresol concentration as well as the presence of dioxygen and hydrogen peroxide on the rate of photocatalytic oxidation was studied.The p-cresol concentration in the irradiated systems was determined by spectroscopic method using α-nitroso-β-naphthol or by the Principal Component Regression method (in the samples with hydrogen peroxide added).The reaction pathway of the photocatalytic oxidation of p-cresol in TiO2 was suggested.
Brezova, Vlasta,Brandsteterova, Eva,Ceppan, Michal,Pies, Juraj
p. 1285 - 1293
(1993)
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Tsuji,Ohno
p. 3969
(1965)
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Mechanism of the redox reaction of the aequorea green fluorescent protein (GFP)
A model compound, 4-(4-hydroxypheny])methylideneimidazol-5 undergoes a reversible redox reaction identical to that of the Aequorea green fluorescent protein (GFP), strongly suggesting that the GFP chromophore is derived via the autoxidation of a nonfluorescent dihydro precursor in dihydro-GFP.
Kojima, Satoshi,Hirano, Takashi,Niwa, Haruki,Ohashi, Mamoru,Inouye, Satoshi,Tsuji, Frederick I.
p. 2875 - 2878
(1997)
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Synthesis and antioxidant properties of a new lipophilic ascorbic acid analogue
4-(4-Hydroxyphenyl)-5-(4-hydroxyphenylmethyl)-2-hydroxyfurane-2-one 1 was prepared by an acidic dimerisation of 4-hydroxyphenylpyruvic acid and some of its antioxidant and spectroscopic properties have been measured and compared to that of ascorbic acid. 1 is as good an antioxidant as ascorbic acid in the DPPH (2,2-diphenyl-1-picryl hydrazyl radical) test and the inhibition of hydroxyl radical and a powerful inhibitor of the Cu2+ or AAPH (2,2′-azobis-(2-amidinopropane) dihydrochloride) induced oxidation of human LDL. 1 gives a stable radical characterised by its ESR spectrum similarly to ascorbic acid but in lower concentration and with a different reactivity towards nitroxides. Theoretical calculations allow us to propose the structure for the radical formed from 1, to explain its lower stability than ascorbyl radical and to evaluate the lipophilicity of 1.
Cotelle, Philippe,Cotelle, Nicole,Teissier, Elisabeth,Vezin, Herve
p. 1087 - 1093
(2003)
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Omura,Matsuura
p. 1516
(1969)
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Template-guided selection of RNA ligands using imine-based dynamic combinatorial chemistry
This study establishes the applicability of imine-based dynamic combinatorial chemistry to discover non-covalent ligands for RNA targets. We elucidate properties underlying the reactivity of arylamines and demonstrate target-guided amplification of tight
Umuhire Juru, Aline,Cai, Zhengguo,Jan, Adina,Hargrove, Amanda E.
p. 3555 - 3558
(2020)
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Acid-promoted reaction of the stilbene antioxidant resveratrol with nitrite ions: Mild phenolic oxidation at the 4′-hydroxystiryl sector triggering nitration, dimerization, and aldehyde-forming routes
In 0.1 M phosphate buffer, pH 3.0, and at 37 °C, resveratrol ((E)-3,4′,5-trihydroxystilbene, 1a), an antioxidant and cancer chemopreventive phytoalexin, reacted smoothly at 25 μM or 1 mM concentration with excess nitrite ions (NO2-) to give a complex pattern of products, including two novel regioisomeric α-nitro (3a) and 3′-nitro (4) derivatives along with some (E)-3,4′,5-trihydroxy-2, 3′-dinitrostilbene (5), four oxidative breakdown products, 4-hydroxybenzaldehyde, 4-hydroxy-3-nitrobenzaldehyde, 3,5- dihydroxyphenylnitromethane, and 3,5-dihydroxybenzaldehyde, two dimers, the resveratrol (E)-dehydrodimer 6 and restrytisol B (7), and the partially cleaved dimer 2. The same products were formed in the absence of oxygen. 1H, 15N HMBC and LC/MS analysis of the crude mixture obtained by reaction of 1a with Na15NO2 suggested the presence of 3,4′,5,β-tetrahydroxy-α-nitro-α,β-dihydrostilbene (8) as unstable intermediate which escaped isolation. Under similar conditions, the structurally related catecholic stilbene piceatannol ((E)-3,3′,4, 5′-tetrahydroxystilbene, 1b) gave, besides (E)-3,3′,4,5′- tetrahydroxy-β-nitrostilbene (3b), 3,4-dihydroxybenzaldehyde and small amounts of 3,5-dihydroxybenzaldehyde. Mechanistic experiments were consistent with the initial generation of the phenoxyl radical of 1a at 4′-OH, which may undergo free radical coupling with NO2 at the α- or 3′-position, to give eventually nitrated derivatives and/or oxidative double bond fission products, or self-coupling, to give dimers. The oxygen-independent, NO2--mediated oxidative fission of the double bond under mild, physiologically relevant conditions is unprecedented in stilbene chemistry and is proposed to involve breakdown of hydroxynitro(so) intermediates of the type 8.
Panzella, Lucia,De Lucia, Maria,Amalfitano, Carmine,Pezzella, Alessandro,Evidente, Antonio,Napolitano, Alessandra,D'Ischia, Marco
p. 4246 - 4254
(2006)
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The Enzyme-catalysed Electrochemical Conversion of p-Cresol into p-Hydroxybenzaldehyde
The electrochemical oxidation of p-cresol was effected enzymically, using either a blue copper protein, azurin, or ferroceneboronic acid as the mediator of the anodic reaction, giving p-hydroxybenzaldehyde as the only product.
Hill, H. Allen O.,Oliver, B. Nigel,Page, David J.,Hopper, David J.
p. 1469 - 1471
(1985)
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Absolute structures of C-glucosides of resveratrol oligomers from Shorea uliginosa
Two C-glucosides of resveratrol dimers (uliginoside A (1) and hemsleyanoloside B (2)) consisting of enantiomeric aglycones and two C-glucosides of resveratrol trimers (uliginosides B (3) and C (4)) consisting of diastereomeric aglycones were isolated from
Ito, Tetsuro,Abe, Naohito,Oyama, Masayoshi,Iinuma, Munekazu
p. 2516 - 2520
(2009)
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Assignment of resonance Raman spectrum of photoactive yellow protein in its long-lived blue-shifted intermediate
Photoactive yellow protein (PYP) is a bacterial photoreceptor containing a 4-hydroxycinnamyl chromophore. We report the resonance Raman spectra for the long-lived blue-shifted intermediate of PYP whose chromophore is isotopically labeled with 13C at the carbonyl carbon atom or at the ring carbon atoms. Spectra have been also measured with PYP in D2O where the phenolic hydroxyl group of the chromophore is deuterated. All of the observed Raman bands are assigned on the basis of the observed isotope shifts and normal mode calculations using a density functional theory. The complete assignment provides a satisfactory framework for future investigations of the photocycle mechanism in PYP by vibrational spectroscopy.
Unno, Masashi,Kumauchi, Masato,Sasaki, Jun,Tokunaga, Fumio,Yamauchi, Seigo
p. 2837 - 2845
(2003)
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A highly photosensitive covalent organic framework with pyrene skeleton as metal-free catalyst for arylboronic acid hydroxylation
Covalent organic frameworks (COFs) have been widely utilized in metal-free photocatalytic synthesis base on their excellent properties such as super conjugation, porosity and stability. In this work, we synthesized a new COF material using 1,3,6,8-Tetrakis (p-formylphenyl)pyrene (TFPPy) and 2,2′-Dimethylbenzidine (DMBZ) as basic units through Schiff base condensation reaction. The new COF (TF-DM COF) was applied as metal-free catalyst for hydroxylation of arylboronic acids. The results indicated that the extended π conjugation of COFs enhanced the absorption of visible light, and the large porosity (BET surface area: 113.782 m2g?1) accelerated the reaction rate. Good recyclability enables it with multiple applications, which result in a great reducing of the cost. This study reports that TF-DM COF has a broad application prospect as a new generation of metal-free photocatalysts for organic conversions.
Chen, Ying,Huo, Jianqiang,Zhang, Yubao
(2022/03/16)

SBA-15 Supported Silver Catalyst for the Efficient Aerobic Oxidation of Toluene Under Solvent-Free Conditions
The efficient SBA-15 supported silver catalysts(Ag/SBA-15) were prepared and characterized by ICP-OES, XRD, TEM, SEM, XPS and N2 adsorption–desorption techniques. The catalysts exhibited an excellent catalytic activity for the aerobic oxidation of toluene to benzaldehyde under solvent-free conditions. Conversion of toluene and selectivity of benzaldehyde were 50% and 89% respectively over catalyst with 9.1 wt% Ag loading (10Ag/SBA-15). A wide range of substrates were tolerated under the selected reaction conditions. The kinetic study shows that the oxidation of toluene over 10Ag/SBA-15 is pseudo-first-order reaction and the activation energy Ea is 45.1?kJ/mol. A plausible mechanism involving oxygen free radicals was proposed for the aerobic oxidation reaction. Compared with the traditional method, the newly designed heterogeneous catalytic system shows better economic applicability, environmental friendliness and broader application prospects. Graphical abstract: [Figure not available: see fulltext.]
Chen, Lei,Chen, Yanjiao,Dai, Xuan,Guo, Jiaming,Peng, Xinhua
(2021/12/09)

Oxidation/ MCR domino protocol for direct transformation of methyl benzene, alcohol, and nitro compounds to the corresponding tetrazole using a three-functional redox catalytic system bearing TEMPO/Co(III)-porphyrin/ Ni(II) complex
A redox catalytic system for oxidation-reduction reactions and the domino preparation of tetrazole compounds from nitro and alcohol precursors was designed, prepared and characterized by UV–vis, GPC, TGA, XRD, EDX, XPS, VSM, FE-SEM, TEM, DLS, BET, NMR, and ICP analyses. The catalyst was prepared via several successive steps by demetalation of chlorophyll b, copolymerization with acrylated TEMPO monomers, complexation with Ni and Co metals (In two different steps), then immobilized on magnetic nanoparticles. The presence of three functional groups including TEMPO, coordinated cobalt, and coordinated nickel in the catalyst, allowed the oxidation of various types of alcohols, alkyl benzenes as well as the reduction of nitro compounds by a single catalyst. All reactions yielded up to 97 % selectivity for oxidation and reduction reactions. Next, the ability of the catalyst to successfully convert alcohol, methyl benzenes and nitro to their corresponding tetrazoles was studied.
Mahmoudi, Boshra,Rostami, Amin,Kazemnejadi, Milad,Hamah-Ameen, Baram Ahmed
(2020/12/21)

Radical-anion coupling through reagent design: hydroxylation of aryl halides
The design and development of an oxime-based hydroxylation reagent, which can chemoselectively convert aryl halides (X = F, Cl, Br, I) into phenols under operationally simple, transition-metal-free conditions is described. Key to the success of this approach was the identification of a reducing oxime anion which can interact and couple with open-shell aryl radicals. Experimental and computational studies support the proposed radical-nucleophilic substitution chain mechanism.
Chechik, Victor,Greener, Andrew J.,James, Michael J.,Oca?a, Ivan,Owens-Ward, Will,Smith, George,Ubysz, Patrycja,Whitwood, Adrian C.
p. 14641 - 14646
(2021/11/17)

Isotruxene-based porous polymers as efficient and recyclable photocatalysts for visible-light induced metal-free oxidative organic transformations
Two new isotruxene-based porous polymers were prepared and demonstrated to be highly efficient, metal-free heterogeneous photocatalysts for oxidative transformations using air as the mild oxidant under visible-light irradiation. Both catalysts show excellent recyclability. In addition, the reactions can be performed in water, further indicating the greenness of this method. This journal is
Zhang, Haowen,Zhang, Xiao,Zheng, Ying,Zhou, Cen
supporting information
p. 8878 - 8885
(2021/11/27)

Coordination Polymers as a Functional Material for the Selective Molecular Recognition of Nitroaromatics and ipso-Hydroxylation of Arylboronic Acids
We report the synthesis and structural characterization of two coordination polymers (CPs), namely; [{Zn(L)(DMF)4} ? 2BF4]α (1) and [{Cd(L)2(Cl)2} ? 2H2O]α (2) (where L=N2,N6-di(pyridin-4-yl)naphthalene-2,6-dicarboxamide). Crystal packing of 1 reveals the existence of channels running along the b- and c-axis filled by the ligated DMF and lattice anions, respectively. Whereas, crystal packing of 2 reveals that the metallacycles of each 1D chain are intercalating into the groove of adjacent metallacycles resulting in the stacking of 1D loop-chains to form a sheet-like architecture. In addition, both 1 and 2 were exploited as multifunctional materials for the detection of nitroaromatic compounds (NACs) as well as a catalyst in the ipso-hydroxylation of aryl/heteroarylboronic acids. Remarkably, 1 and 2 showed high fluorescence stability in an aqueous medium and displayed a maximum 88% and 97% quenching efficiency for 4-NPH, respectively among all the investigated NACs. The mechanistic investigation of NACs recognition suggested that the fluorescence quenching occurred via electron as well as energy transfer process. Furthermore, the ipso-hydroxylation of aryl/heteroarylboronic acids in presence of 1 and 2 gave up to 99% desired product yield within 15 min in our established protocol. In both cases, 1 and 2 are recyclable upto five cycles without any significant loss in their efficiency.
Bhasin, K. K.,Husain, Ahmad,Kumar, Girijesh,Rani, Pooja
(2021/12/06)

A Dual-Function Highly Crystalline Covalent Organic Framework for HCl Sensing and Visible-Light Heterogeneous Photocatalysis
Covalent organic frameworks (COFs) offer great potential for various advanced applications such as photocatalysis, sensing, and so on because of their fully conjugated, porous, and chemically stable unique structural architecture. In this work, we have designed and developed a truxene-based ultrastable COF (Tx-COF-2) by Schiff-base condensation between 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 5,5,10,10,15,15-hexamethyl-10,15-dihydro-5H-diindeno(1,2-a:1′,2′-c)fluorene-2,7,12-tricarbaldehyde (Tx-CHO) for the first time. The resulting COF possesses excellent crystallinity, permanent porosity, and high Brunauer-Emmett-Teller (BET) surface areas (up to 1137 m2 g-1). The COF was found to be a heterogeneous, recyclable photocatalyst for efficient conversion of arylboronic acids to phenols under visible-light irradiation, an environmentally friendly alternative approach to conventional metal-based photocatalysis. Besides, Tx-COF-2 provides an immediate naked-eye color change (1 s) and fluorescence "turn-on"phenomena upon exposure to HCl. The response is highly sensitive, with an ultralow detection limit of up to 4.5 nmol L-1.
Addicoat, Matthew A.,Nailwal, Yogendra,Pal, Santanu Kumar,Wonanke, A. D. Dinga
p. 6595 - 6604
(2021/07/20)

The graphite-catalyzed: ipso -functionalization of arylboronic acids in an aqueous medium: metal-free access to phenols, anilines, nitroarenes, and haloarenes
An efficient, metal-free, and sustainable strategy has been described for the ipso-functionalization of phenylboronic acids using air as an oxidant in an aqueous medium. A range of carbon materials has been tested as carbocatalysts. To our surprise, graphite was found to be the best catalyst in terms of the turnover frequency. A broad range of valuable substituted aromatic compounds, i.e., phenols, anilines, nitroarenes, and haloarenes, has been prepared via the functionalization of the C-B bond into C-N, C-O, and many other C-X bonds. The vital role of the aromatic π-conjugation system of graphite in this protocol has been established and was observed via numerous analytic techniques. The heterogeneous nature of graphite facilitates the high recyclability of the carbocatalyst. This effective and easy system provides a multipurpose approach for the production of valuable substituted aromatic compounds without using any metals, ligands, bases, or harsh oxidants.
Badgoti, Ranveer Singh,Dandia, Anshu,Parewa, Vijay,Rathore, Kuldeep S.,Saini, Pratibha,Sharma, Ruchi
p. 18040 - 18049
(2021/05/29)

Application of Electron-Rich Covalent Organic Frameworks COF-JLU25 for Photocatalytic Aerobic Oxidative Hydroxylation of Arylboronic Acids to Phenols
Visible-light-driven organic reactions are environmentally friendly green chemical transformations among which photosynthetic oxidative hydroxylation of arylboronic acids to phenols has attracted increasing research interest during the very recent years. Given the efficiency and reusability of heterogeneous catalysts, COF-JLU25, an electron-rich COF-based photocatalyst constructed by integrating electron-donating blocks 1,3,6,8-tetrakis(4-aminophenyl)pyrene (PyTA) and 4-[4-(4-formylmethyl)-2,5-dimethoxyphenyl] benzaldehyde (TpDA), was selected as a photocatalyst for the oxidative hydroxylation of arylboronic acids. In our studies, COF-JLU25 demonstrated excellent photocatalytic activity with high efficiency, robust reusability, and low catalyst loading, showcasing an application potential of previously underexplored COF-based photocatalyst composed solely of electron-rich units.
Xiao, Guangjun,Li, Wenqian,Chen, Tao,Hu, Wei-Bo,Yang, Hui,Liu, Yahu A.,Wen, Ke
supporting information
p. 3986 - 3991
(2021/03/29)

Transforming a Fluorochrome to an Efficient Photocatalyst for Oxidative Hydroxylation: A Supramolecular Dimerization Strategy Based on Host-Enhanced Charge Transfer
The development of non-covalent synthetic strategy to fabricate efficient photocatalysts is of great importance in theranostic and organic materials. Herein, a fluorochrome N,N′-dimethyl 2,5-bis(4-pyridinium)thiazolo[5,4-d]thiazolediiodide (MPT) was transformed into an efficient photocatalyst through supramolecular dimerization in the cavity of cucurbit[8]uril (CB[8]). The host-enhanced charge transfer interaction within the supramolecular dimer 2MPT-CB[8] dramatically promoted intersystem crossing to produce triplet. In addition, the staggered conformation of 2MPT-CB[8] facilitated the energy transfer and electron transfer of the triplet. As a result, 2MPT-CB[8] could serve as a high-efficiency photocatalyst for the oxidative hydroxylation of arylboronic acids. This supramolecular dimerization strategy enriches the supramolecular engineering of functional π-systems. It is anticipated that this strategy can be extended to fabricate various π-systems with tailor-made functions.
Tang, Bohan,Xu, Weiquan,Xu, Jiang-Fei,Zhang, Xi
supporting information
p. 9384 - 9388
(2021/03/22)

β-Diketone boron difluoride dye-functionalized conjugated microporous polymers for efficient aerobic oxidative photocatalysis
Incorporation of organic chromophores into conjugated micro/mesoporous polymers (CMPs) provides a promising avenue for developing recyclable heterogeneous photocatalysts by overcoming tedious separation and low reusability of homogeneous organic dye-based photocatalysts. However, the design principle and the underlying structure-property relationship for fabricating and selecting various organic dye-embedded CMPs for efficient photocatalysis have not been well-constructed so far. In this study, we described the rational fabrication of two new CMPsviathe one-step Sonogashira coupling using β-diketone boron difluoride dye as the key linker and commonly used building blocks (triphenylamine/triphenylbenzene) as the cores. The resulting boron-dye containing CMPs were efficiently employed as the metal-free photocatalysts in two typical aerobic oxidative organic transformations including coupling of benzylamine and oxidation of aryl boronic acids to corresponding aryl phenols, which have never been explored with other boron-dye-embedded CMPs. They exhibited superior photocatalytic performance compared to their boron-free counterparts due to their wide visible-light absorption, narrow optical bandgaps, and extended π-conjugation due to boron-complexation. The present study establishes β-diketone boron difluoride dyes as efficient building blocks for fabricating new CMP-based photocatalysts.
Dong, Kaixun,Gong, Weitao,Hassan, Mehdi,Liu, Lu,Ning, Guiling
p. 3905 - 3913
(2021/06/18)

Rapid biosynthesis of phenolic glycosides and their derivatives from biomass-derived hydroxycinnamates
Biomass-derived hydroxycinnamates (mainly includingp-coumaric acid and ferulic acid), which are natural sources of aromatic compounds, are highly underutilized resources. There is a need to upgrade them to make them economically feasible. Value-added phenolic glycosides and their derivatives, both belonging to a class of plant aromatic natural products, are widely used in the nutraceutical, pharmaceutical, and cosmetic industries. However, their complex aromatic structures make their efficient biosynthesis a challenging process. To overcome this issue, we created three novel synthetic cascades for the biosynthesis of phenolic glycosides (gastrodin, arbutin, and salidroside) and their derivatives (hydroquinone, tyrosol, hydroxytyrosol, and homovanillyl alcohol) fromp-coumaric acid and ferulic acid. Moreover, because the biomass-derived hydroxycinnamates directly provided aromatic units, the cascades enabled efficient biosynthesis. We achieved substantially high production rates (up to or above 100-fold enhancement) relative to the glucose-based biosynthesis. Given the ubiquity of the aromatic structure in natural products, the use of biomass-derived aromatics should facilitate the rapid biosynthesis of numerous aromatic natural products.
Zhao, Mingtao,Hong, Xulin,Abdullah,Yao, Ruilian,Xiao, Yi
p. 838 - 847
(2021/02/09)

Nickel Hydride Catalyzed Cleavage of Allyl Ethers Induced by Isomerization
This report discloses the deallylation of O - and N -allyl functional groups by using a combination of a Ni-H precatalyst and excess Bronsted acid. Key steps are the isomerization of the O - or N -allyl group through Ni-catalyzed double-bond migration followed by Bronsted acid induced O/N-C bond hydrolysis. A variety of functional groups are tolerated in this protocol, highlighting its synthetic value.
Kathe, Prasad M.,Berkefeld, Andreas,Fleischer, Ivana
supporting information
p. 1629 - 1632
(2021/02/09)

Photocatalytic Reductive C-O Bond Cleavage of Alkyl Aryl Ethers by Using Carbazole Catalysts with Cesium Carbonate
Methods to activate the relatively stable ether C-O bonds and convert them to other functional groups are desirable. One-electron reduction of ethers is a potentially promising route to cleave the C-O bond. However, owing to the highly negative redox potential of alkyl aryl ethers (Ered -2.6 V vs SCE), this mode of ether C-O bond activation is challenging. Herein, we report the visible-light-induced photocatalytic cleavage of the alkyl aryl ether C-O bond using a carbazole-based organic photocatalyst (PC). Both benzylic and non-benzylic aryl ethers underwent C-O bond cleavage to form the corresponding phenol products. Addition of Cs2CO3 was beneficial, especially in reactions using a N-H carbazole PC. The reaction was proposed to occur via single-electron transfer (SET) from the excited-state carbazole to the substrate ether. Interaction of the N-H carbazole PC with Cs2CO3 via hydrogen bonding exists, which enables a deprotonation-assisted electron-transfer mechanism to operate. In addition, the Lewis acidic Cs cation interacts with the substrate alkyl aryl ether to activate it as an electron acceptor. The high reducing ability of the carbazole combined with the beneficial effects of Cs2CO3 made this otherwise formidable SET event possible.
Yabuta, Tatsushi,Hayashi, Masahiko,Matsubara, Ryosuke
p. 2545 - 2555
(2021/02/01)

Biocatalytic Cross-Coupling of Aryl Halides with a Genetically Engineered Photosensitizer Artificial Dehalogenase
Devising artificial photoenzymes for abiological bond-forming reactions is of high synthetic value but also a tremendous challenge. Disclosed herein is the first photobiocatalytic cross-coupling of aryl halides enabled by a designer artificial dehalogenase, which features a genetically encoded benzophenone chromophore and site-specifically modified synthetic NiII(bpy) cofactor with tunable proximity to streamline the dual catalysis. Transient absorption studies suggest the likelihood of energy transfer activation in the elementary organometallic event. This design strategy is viable to significantly expand the catalytic repertoire of artificial photoenzymes for useful organic transformations.
Fu, Yu,Huang, Jian,Wu, Yuzhou,Liu, Xiaohong,Zhong, Fangrui,Wang, Jiangyun
supporting information
p. 617 - 622
(2021/02/03)

Preparation method of P-hydroxybenzaldehyde
The invention relates to a preparation method of p-hydroxybenzaldehyde, which comprises the steps of (1) by taking aluminum salt and/or zinc salt as a catalyst, carrying out condensation reaction on phenol and glyoxylic acid under an alkaline condition to obtain 4-hydroxymandelic acid; and (2) oxidizing 4-hydroxymandelic acid serving as a raw material with copper ferrite serving as a catalyst to obtain p-hydroxybenzaldehyde. Compared with the prior art, the method has the advantages of easily available raw materials, mild reaction conditions, high yield and the like.
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Paragraph 0066-0069; 0071-0073; 0075-0076; 0078-0079; ...

(2021/07/17)

Evaluation of 2-(piperidine-1-yl)-ethyl (PIP) as a protecting group for phenols: Stability to ortho-lithiation conditions and boiling concentrated hydrobromic acid, orthogonality with most common protecting group classes, and deprotection via Cope elimination or by mild Lewis acids
A new protecting group, 2-(piperidine-1-yl)-ethyl (PIP), was evaluated as a protecting group for phenols. The PIP group was stable to ortho-lithiation conditions and refluxing with concentrated hydrobromic acid. Deprotection was accomplished by two routes, oxidation to N-oxides followed by Cope elimination (CE) and subsequent hydrolysis or ozonolysis of the vinyl ether or one-step deprotection by BBr3?Me2S. The PIP group is orthogonal to the O-benzyl, O-acetyl, O-t-butyldiphenylsilyl, O-methyl, O-p-methoxybenzyl, O-allyl, O-tetrahydropyranyl and N-t-butoxy carbonyl groups. The CE step was systematically studied and was found to give higher yields when the reaction was performed in the presence of silylating agents.
Norén, Rolf
(2021/04/07)

PhIO-Mediated oxidative dethioacetalization/dethioketalization under water-free conditions
Treatment of thioacetals and thioketals with iodosobenzene in anhydrous DCM conveniently afforded the corresponding carbonyl compounds in high yields under water-free conditions. The mechanistic studies indicate that this dethioacetalization/dethioketalization process does not need water and the oxygen of the carbonyl products comes from the hypervalent iodine reagent.
Du, Yunfei,Ouyang, Yaxin,Wang, Xi,Wang, Xiaofan,Yu, Zhenyang,Zhao, Bingyue,Zhao, Kang
p. 48 - 65
(2021/06/16)

Electrochemical-induced hydroxylation of aryl halides in the presence of Et3N in water
A thorough study of mild and environmentally friendly electrochemical-induced hydroxylation of aryl halides without a catalyst is presented. The best protocol consists of hydroxylation of different aryl iodides and aryl bromides by water solution in the presence of Et3N under air, affording the target phenols in good isolated yields. Moreover, aryl chlorides were successfully employed as substrates. This methodology also provides a direct pathway for the formation of deoxyphomalone, which displayed a significant anti-proliferation effect.
Ke, Fang,Lin, Chen,Lin, Mei,Long, Hua,Wu, Mei,Yang, Li,Zhuang, Qinglong
supporting information
p. 6417 - 6421
(2021/08/03)

Hydroxyl radical-mediated oxidative cleavage of CC bonds and further esterification reaction by heterogeneous semiconductor photocatalysis
A hydroxyl radical-mediated aerobic cleavage of alkenes and further sequence esterification reaction for the preparation of carbonyl compounds have been developed by using tubular carbon nitride (TCN) as a general heterogeneous photocatalyst under an oxygen atmosphere with visible light irradiation. This protocol has an excellent substrate scope and gives the desired aldehydes, ketones and esters in moderate to high yields. Importantly, this metal-free procedure employed photogenerated hydroxyl radicals in situ as green oxidation active species, avoiding the present additional initiators. The reaction could be carried out under solar light irradiation and was applicable to large-scale reactions. Furthermore, the recyclable TCN catalyst could be used several times without a significant loss of activities.
Hong, Mei,Jia, Rui,Miao, Hongyan,Ni, Bangqing,Niu, Tengfei,Wang, Hui
p. 6591 - 6597
(2021/09/10)

C=C Bond Oxidative Cleavage of BODIPY Photocages by Visible Light
Photocages for protection and the controlled release of bioactive compounds have been widely investigated. However, the vast majority of these photocages employ the cleavage of single bonds and high-energy ultraviolet light. The construction of a photoactivation system that uses visible light to cleave unsaturated bonds still remains a challenge. Herein, we report a regioselective oxidative cleavage of C=C bonds from a boron-dipyrrolemethene (BODIPY)-based photocage by illumination at 630 nm, resulting in a free aldehyde and a thiol fluorescent probe. This strategy was demonstrated in live HeLa cells, and the generated α-formyl-BODIPY allowed real-time monitoring of aldehyde release in the cells. In particular, it is shown that a mannose-functionalized photocage can target HepG2 cells.
Gao, Quan,Geng, Jin,He, Rongkun,Lin, Shanmeng,Ng, Dennis K. P.,Xu, Youwei,Zhang, Yichuan
supporting information
p. 11268 - 11272
(2021/07/14)

Atomically Dispersed Pt-N3C1Sites Enabling Efficient and Selective Electrocatalytic C-C Bond Cleavage in Lignin Models under Ambient Conditions
Selective cleavage of C-C linkages is the key and a challenge for lignin degradation to harvest value-added aromatic compounds. To this end, electrocatalytic oxidation presents a promising technique by virtue of mild reaction conditions and strong sustainability. However, the existing electrocatalysts (traditional bulk metal and metal oxides) for C-C bond oxidative cleavage suffer from poor selectivity and low product yields. We show for the first time that atomically dispersed Pt-N3C1sites planted on nitrogen-doped carbon nanotubes (Pt1/N-CNTs), constructed via a stepwise polymerization-carbonization-electrostatic adsorption strategy, are highly active and selective toward Cα-Cβbond cleavage in β-O-4 model compounds under ambient conditions. Pt1/N-CNTs exhibits 99% substrate conversion with 81% yield of benzaldehyde, which is exceptional and unprecedented compared with previously reported electrocatalysts. Moreover, Pt1/N-CNTs using only 0.41 wt % Pt achieved a much higher benzaldehyde yield than those of the state-of-the-art bulk Pt electrode (100 wt % Pt) and commercial Pt/C catalyst (20 wt % Pt). Systematic experimental investigation together with density functional theory (DFT) calculation suggests that the superior performance of Pt1/N-CNTs arises from the atomically dispersed Pt-N3C1sites facilitating the formation of a key Cβradical intermediate, further inducing a radical/radical cross-coupling path to break the Cα-Cβbond. This work opens up opportunities in lignin valorization via a green and sustainable electrochemical route with ultralow noble metal usage.
Cui, Tingting,Ma, Lina,Wang, Shibin,Ye, Chenliang,Liang, Xiao,Zhang, Zedong,Meng, Ge,Zheng, Lirong,Hu, Han-Shi,Zhang, Jiangwei,Duan, Haohong,Wang, Dingsheng,Li, Yadong
supporting information
p. 9429 - 9439
(2021/07/19)

A Magnetically Recyclable Palladium-Catalyzed Formylation of Aryl Iodides with Formic Acid as CO Source: A Practical Access to Aromatic Aldehydes
A magnetically recyclable palladium-catalyzed formylation of aryl iodides under CO gas-free conditions has been developed by using a bidentate phosphine ligand-modified magnetic nanoparticles-anchored- palladium(II) complex [2P-Fe 3O 4@SiO 2-Pd(OAc) 2] as catalyst, yielding a wide variety of aromatic aldehydes in moderate to excellent yields. Here, formic acid was employed as both the CO source and the hydrogen donor with iodine and PPh 3as the activators. This immobilized palladium catalyst can be obtained via a simple preparative procedure and can be facilely recovered simply by using an external magnetic field, and reused at least 9 times without any apparent loss of catalytic activity.
You, Shengyong,Zhang, Rongli,Cai, Mingzhong
p. 1962 - 1970
(2021/01/25)

Method for preparing alcohol and phenol through aerobic hydroxylation reaction of boric acid derivative in absence of photocatalyst
The invention discloses a method for preparing alcohol and phenol through aerobic hydroxylation reaction of a boric acid derivative in the absence of a photocatalyst, wherein the boric acid derivativeis aryl boronic acid or alkyl boronic acid, and the corresponding target compounds are respectively a phenol-based compound and an alcohol-based compound. According to the method, by using a boric acid derivative as a reaction substrate, an additive is added under a solvent condition, and a hydroxylation reaction is performed under aerobic and illumination conditions to obtain a corresponding target compound. According to the invention, the new strategy is provided for the synthesis of phenols through aerobic hydroxylation of aryl boronic acid without a photocatalyst; the catalyst-free aerobic hydroxylation method for photocatalysis of aryl boronic acid or alkyl boronic acid by using triethylamine as an additive is firstly disclosed; and the new method has advantages of photocatalyst-freecondition, wide substrate range and good functional group compatibility.
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Paragraph 0025-0028; 0030-0032

(2020/01/25)

Method for synthesizing phenol or derivative thereof in aqueous phase by photocatalytic one-pot method
The invention discloses a method for synthesizing phenol or a derivative thereof in an aqueous phase by a photocatalytic one-pot method. The method comprises the following steps: by taking a compoundaryl halide shown in formula (I) as a raw material and water as a solvent, adding a catalyst and an auxiliary agent, and carrying out reacting under the conditions of alkali and visible light to obtain the phenol or the derivative (II) thereof. Compared with the prior art, the method is applicable to a large number of functional groups, high in yield, few in byproducts, simple and safe to operate,low in cost and environmentally friendly, wherein R is selected from substituted or non-substituted phenyl, pyridyl, quinolyl or pyrimidinyl; X is selected from halogen; the substituted phenyl is substituted by C1-C4 alkyl, C1-C4 alkoxy, hydroxyl, halogen, cyano, aldehyde group, nitro, amino, acetyl or carboxyl; and the substituted pyridyl, quinolyl or pyrimidinyl is pyridyl, quinolyl or pyrimidinyl substituted by C1-C4 alkyl.
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Paragraph 0032-0033; 0050-0051; 0085-0106

(2020/12/08)

Visible-light assisted of nano Ni/g-C3N4 with efficient photocatalytic activity and stability for selective aerobic C?H activation and epoxidation
A selective, economical, and ecological protocol has been described for the oxidation of methyl arenes and their analogs to the corresponding carbonyl compounds and epoxidation reactions of alkenes with molecular oxygen (O2) or air as a green oxygen source, under mild reaction conditions. The nano Ni/g-C3N4 exhibited high photocatalytic activity, stability, and selectivity in the C?H activation of methyl arenes, methylene arenes, and epoxidation of various alkenes under visible- light irradiation without the use of an oxidizing agent and under base free conditions.
Akrami, Zahra,Hosseini-Sarvari, Mona
supporting information

(2020/10/13)

A Remote ‘Imidazole’-Based Ruthenium(II) Para-Cymene Pre-catalyst for the Selective Oxidation Reaction of Alkyl Arenes and Alcohols
Herein we disclosed the use of a remote ‘imidazole’-based precatalyst [(para-cymene)RuII(L)Cl]+, C-1 where L=2-(4-substituted-phenyl)-1H-imidazo[4,5-f][1,10] phenanthroline) for the selective oxidation of a variety of alkyl arenes/heteroarenes and alcohols to their corresponding aldehydes or ketones in presence of tert-butyl hydroperoxide (TBHP). The remote ‘imidazole’ moiety present in the complex facilitates the activation of oxidant and subsequent generation of active species via the release of para-cymene from C-1, which in-turn was less effective without the ‘imidazole’ moiety. The mechanistic features of C-1 promoted oxidation of alkyl arenes were also assessed from spectroscopic, kinetic, and few control experiments. The substrate scope for C-1 promoted oxidation reaction was assessed based on the selective oxidation of 27-different alkyl arenes/heteroarenes and 25 different alcohols to their corresponding aldehydes/ketones in moderate to good yields.
Dutta, Manali,Bania, Kusum K.,Pratihar, Sanjay
p. 926 - 932
(2020/03/05)

Green and selective toluene oxidation–Knoevenagel-condensation domino reaction over Ce- and Bi-based CeBi mixed oxide mixtures
Both Bi- and Ce-based CeBi mixed oxides were prepared by a modified sol-gel process from their precursor salts. The mixed as well as the parent oxides were characterized by X-ray diffractometry, Raman, XPS, UV–DRS and X-ray photoelectron spectroscopies, ICP–OES method, scanning and transmission electron microscopies as well as BET surface area, CO2- and NH3-temperature-programmed desorption measurements. After characterizing the morphology, the acid-base properties, the oxidation states of the cationic components and the porosity of these structures, their catalytic activities were probed in the Koevenagel condensation of benzaldehyde and diethyl malonate and the toluene oxidation to benzaldehyde reactions. Based on the catalytic activities of the oxides in the individual reactions, a catalyst mixture from the Bi- and Ce-based mixed oxides was used successfully in the toluene to benzaldehyde oxidation and benzaldehyde to benzylidene malonate Knoevenagel condensation domino reaction under environmentally benign conditions.
Varga, Gábor,Kukovecz, ákos,Kónya, Zoltán,Sipos, Pál,Pálinkó, István
p. 308 - 315
(2019/11/29)

An efficient base and H2O2 free protocol for the synthesis of phenols in water and oxygen using spinel CuFe2O4 magnetic nanoparticles
An efficient base and H2O2 free protocol was used for the synthesis of phenols from boronic acids using biogenic CuFe2O4 magnetic nanoparticles as catalyst at room temperature in water and oxygen. The catalyst was prepared using the flowers of Lantana camara. The size of the nanoparticles was 4.27 nm. Base free and ligand free protocol, less time, excellent yields, room temperature, biogenic synthesis of the catalyst, use of O2 as an environmentally friendly oxidant are the advantages of the present protocol. The recyclability of the catalyst was for 5 cycles without loss of magnetic property or catalytic activity.
Chutia, Rituparna,Chetia, Bolin
p. 1925 - 1936
(2020/08/13)

A scalable and green one-minute synthesis of substituted phenols
A mild, green and highly efficient protocol was developed for the synthesis of substituted phenols via ipso-hydroxylation of arylboronic acids in ethanol. The method utilizes the combination of aqueous hydrogen peroxide as the oxidant and H2O2/HBr as the reagent under unprecedentedly simple and convenient conditions. A wide range of arylboronic acids were smoothly transformed into substituted phenols in very good to excellent yields without chromatographic purification. The reaction is scalable up to at least 5 grams at room temperature with one-minute reaction time and can be combined in a one-pot sequence with bromination and Pd-catalyzed cross-coupling to generate more diverse, highly substituted phenols.
Elumalai, Vijayaragavan,Hansen, J?rn H.
p. 40582 - 40587
(2020/11/18)

Aerobic photooxidative hydroxylation of boronic acids catalyzed by anthraquinone-containing polymeric photosensitizer
We report herein the synthesis of a polymeric photosensitizer and its application in aerobic photooxidative hydroxylation of boronic acids. The polymeric photosensitizer was synthesized by the condensation of anthraquinone-2-carbonyl chloride (AQ-2-COCl) with poly (2-hydroxyethyl methacrylate) (PHEMA). The photo-oxidative hydroxylation of boronic acids using anthraquinone-containing-poly (2-hydroxyethyl methacrylate) (AQ-PHEMA) was then explored and shown to exhibit high efficiency and broad scope. Moreover, AQ-PHEMA could be easily recovered and reused for more than 20 times without significant loss of the catalytic activity.
Chen, Yang,Ding, Aishun,Hu, Jianhua
p. 7927 - 7932
(2020/03/11)

Highly Porous Polycaprolactone Membrane: A Biocompatible Promotor for Oxidative Hydroxylation of Arylboronic Acids
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Kwon, Gyu-Tae,Lim, In-Kyun,Shin, Ueon Sang,Kim, Seung-Hoi
supporting information
p. 574 - 577
(2020/05/25)

Quaternary ammonium hydroxide-functionalized g-C3N4 catalyst for aerobic hydroxylation of arylboronic acids to phenols
A new and efficient metal-free approach toward the synthesis of phenols via an aerobic hydroxylation of arylboronic acids by using a novel quaternary ammonium hydroxide g-C3N4 catalyst has been described. The functionalized quaternary ammonium hydroxide (g-C3N4-OH) has been prepared from graphitic carbon nitride (g-C3N4) scaffold by converting the residual –NH2 and –NH groups to quaternary methyl ammonium iodide by performing a methylation reaction with methyl iodide followed by ion-exchange with 0.1 N KOH or anion exchange resin Amberlyst A26 (OH- form) by post-synthetic modification. The resultant g-C3N4-OH was characterized by XRD, FTIR, field-emission scanning electron microscope (FESEM), high-resolution transmission electron microscope (HRTEM), N2 adsorption/desorption isotherms, and acid–base titration. Tested as solid-base catalysts, the g-C3N4-OH showed excellent catalytic activity in the aerobic hydroxylation reaction by converting a variety of arylboronic acids to the corresponding phenols in high yields. More importantly, the g-C3N4-OH solid-base has been successfully reused four times with the minor loss of initial catalytic activity (10.5percent).
Muhammad, Ibrahim,Mannathan, Subramaniyan,Sasidharan, Manickam
p. 1470 - 1476
(2020/07/13)

Trinuclear Mn2+/Zn2+based microporous coordination polymers as efficient catalysts foripso-hydroxylation of boronic acids
Two microporous coordination polymers based on hourglass trinuclear building units, [Mn3(bpdc)3(bpy)]·2DMF and [Zn3(bpdc)3(bpy)]·2DMF·4H2O (bpdc = 4,4′-biphenyl dicarboxylic acid, bpy = 4,4′-bipyridine), have been synthesized under solvothermal conditions employing DMF as the solvent. Each structure consists of two crystallographically distinct M2+(M1 and M2) centers that are connectedviacarboxylate bridges from six bpdc ligands, generating a trinuclear metal cluster, [M3(bpdc)3(bpy)]. Cluster representation of the structure resulted in an interpenetrated net of rarehextopological type. Catalytic activities of the CPs have been assessed for the oxidative hydroxylation of phenylboronic acids (PBAs) using aqueous hydrogen peroxide (H2O2). Various substituted aryl/hetero-arylboronic acids RB(OH)2[R = phenyl, 2,4-difluorophenyl, 4-aminophenyl, 2-thiopheneetc.] underwentipso-hydroxylation smoothly at room temperature to generate the corresponding phenols in excellent yields. The main advantages of this protocol are the aqueous medium reaction, heterogeneous catalytic system, and short reaction time with excellent yield.
Bora, Sanchay J.,Dutta, Anurag,Goswami, Shyam,Guha, Ankur K.,Paul, Rima,Thakur, Ashim J.
p. 5454 - 5462
(2020/05/16)

Nickel-catalyzed oxidative hydroxylation of arylboronic acid: Ni(HBTC)BPY MOF as an efficient and ligand-free catalyst to access phenolic motifs
A straightforward and mild oxidative ipso-hydroxylation of arylboronic acids has been achieved using a simple and non-noble metal, nickel-based reusable heterogeneous catalyst Ni(HBTC)BPY MOF (HBTC = benzene-1,3,5-tricarboxylate, BPY = 4,4′-bipyridine) in the presence of benign hydrogen peroxide as an oxidant under ambient reaction condition. The Ni(HBTC)BPY MOF exhibits excellent catalytic activity towards the formation of phenols from diverse arylboronic acids within short time and can be reused up to five times without any notable loss in its activity as well as shown high functional group tolerance even in the presence of sensitive functionalities and useful to achieve hydroxyl group in heterocycles.
Latha, Ganesapandian,Devarajan, Nainamalai,Karthik, Murugan,Suresh, Palaniswamy
(2020/01/08)

Copper nanoparticles supported on highly nitrogen-rich covalent organic polymers as heterogeneous catalysts for the ipso -hydroxylation of phenyl boronic acid to phenol
This work describes a simple procedure for the synthesis of highly nitrogen-rich covalent organic polymers using commercially available starting materials like melamine and cyanuric chloride as a solid heterogeneous catalyst Cu/TCOP under solvothermal conditions. The structural properties of the as-synthesized solid heterogeneous catalyst were determined by X-ray diffraction (XRD), diffuse reflectance spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), 13C-CP MAS nuclear magnetic resonance spectroscopy and X-ray photoelectron spectroscopy. The catalytic activity of Cu/TCOP was investigated by focusing on the oxidation of phenylboronic acid under atmospheric conditions in an aqueous medium, achieving a very good yield up to 99%. The reaction performance was evaluated considering the effect of various parameters, such as the amount of the catalyst, reaction time, temperature, and the amount of the base and solvent. The Cu/TCOP catalyst is completely recoverable in a facile manner from the reaction mixture and the efficiency of the copper nanocatalyst can be recovered after five cycles.
Sadhasivam, Velu,Harikrishnan, Muniyasamy,Elamathi, Ganesan,Balasaravanan, Rajendran,Murugesan, Sepperumal,Siva, Ayyanar
supporting information
p. 6222 - 6231
(2020/05/13)

Highly effective near-infrared activating tripleta-triplet annihilation upconversion for photoredox catalysis
Organic triplet-triplet annihilation upconversion (TTA-UC) materials have considerable promise in areas as broad as biology, solar energy harvesting, and photocatalysis. However, the development of highly efficient near-infrared (NIR) light activatable TTA-UC systems remains extremely challenging. In this work, we report on a method of systematically tailoring an annihilator to attain such outstanding systems. By chemical modifications of a commonly used perylene annihilator, we constructed a family of perylene derivatives that have simultaneously tailored triplet excited state energy (T1) and singlet excited state energy (S1), two key annihilator factors to determine TTAUC performance. Via this method, we were able to tune the TTAUC system from an endothermic type to an exothermic one, thus significantly elevating the upconversion performance of NIR light activatable TTA upconversion systems. In conjunction with the photosensitizer PdTNP (10 μM), the upconversion efficiency using the optimal annihilator (100 μM) identified in this study was measured to be 14.1% under the low-power density of NIR light (100 mW/cm2, 720 nm). Furthermore, using such a low concentration of perylene derivative, we demonstrated that the optimal TTA-UC pair developed in our study can act as a highly effective light wavelength up-shifter to enable NIR light to drive a photoredox catalysis that otherwise requires visible light. We found that such an NIR driven method is highly effective and can even surpass directly visible light driven photoredox catalysis. This method is important for photoredox catalysis as NIR light can penetrate much deeper in colored photoredox catalysis reaction solutions, especially when done in a large-scale manner. Furthermore, this TTA-UC mediated photoredox catalysis reaction is found to be outdoor sunlight operable. Thus, our study provides a solution to enhance NIR activatable organic upconversion and set the stage for a wide array of applications that have previously been limited by the suboptimal efficiency of the existing TTA upconversion materials.
Huang, Ling,Wu, Wenting,Li, Yang,Huang, Kai,Zeng, Le,Lin, Wenhai,Han, Gang
supporting information
p. 18460 - 18470
(2020/11/17)

Helical Carbenium Ion: A Versatile Organic Photoredox Catalyst for Red-Light-Mediated Reactions
Red light has the advantages of low energy, less health risks, and high penetration depth through various media. Herein, a helical carbenium ion (N,N′-di-n-propyl-1,13-dimethoxyquinacridinium (nPr-DMQA+) tetrafluoroborate) has been used as an organic photoredox catalyst for photoreductions and photooxidations in the presence of red light (λmax = 640 nm). It has catalyzed red-light-mediated dual transition-metal/photo-redox-catalyzed C-H arylation and intermolecular atom-transfer radical addition through oxidative quenching. Moreover, its potential in photooxidation catalysis has also been demonstrated by successful applications in red-light-induced aerobic oxidative hydroxylation of arylboronic acids and benzylic C(sp3)-H oxygenation through reductive quenching. Thus, a versatile organic photoredox catalyst (helical carbenium ion) for red-light-mediated photoredox reactions has been developed.
Mei, Liangyong,Veleta, José M.,Gianetti, Thomas L.
supporting information
p. 12056 - 12061
(2020/08/07)

Rongalite-promoted metal-free aerobic ipso-hydroxylation of arylboronic acids under sunlight: DFT mechanistic studies
A novel rongalite-promoted metal-free aerobic ipso-hydroxylation of arylboronic acids has been developed. This method employs low-cost rongalite as a radical initiator and O2 as a green oxidizing agent for ipso-hydroxylation. This protocol is compatible with a wide variety of functional groups with good to excellent yields at room temperature. Furthermore, mechanistic insight into the role of superoxide radical anions in C-B cleavage has also been provided based on DFT studies.
Golla, Sivaparwathi,Poshala, Soumya,Pawar, Ravinder,Kokatla, Hari Prasad
supporting information

(2019/12/27)

Bimetallic photoredox catalysis: Visible light-promoted aerobic hydroxylation of arylboronic acids with a dirhodium(ii) catalyst
We report the use of a rhodium(II) dimer in visible light photoredox catalysis for the aerobic oxidation of arylboronic acids to phenols under mild conditions. Spectroscopic and computational studies indicate that the catalyst Rh2(bpy)2(OAc)4 (1) undergoes metal-metal to ligand charge transfer upon visible light irradiation, which is responsible for catalytic activity. Further reactivity studies demonstrate that 1 is a general photoredox catalyst for diverse oxidation reactions.
Campbell, Michael G.,Chuang, Gary Jing,Liu, Ming-Lun,Miura-Stempel, Emily,Tu, Jing-Wen,Yang, Hsiang-Ming
p. 2040 - 2047
(2020/03/13)

Optimizing the crystallization process of conjugated polymer photocatalysts to promote electron transfer and molecular oxygen activation
Photocatalytic reactive oxygen species (ROS)-induced reactions provide an appealing method to solve the environmental and energy issues, whereas the current oxidation reaction generally suffered from low efficiency and poor selectivity due to uncontrollable O2 activation process. In view of the existence of competitive electron and energy transfer pathway, we propose that highly efficient superoxide radical anion (·O2?) generation can be achieved by optimizing the order degree of the photocatalyst. Herein, by taking carbon nitride polymer as an example, we optimized the crystallization process of carbon nitride polymer by selecting precursors of different polymerization degrees with a molten salt method. Benefiting from the high crystallinity, extended π-conjugated system and strong van der-Waals interactions between interlayers, the modified carbon nitride polymer exhibited accelerated charge transport and enhancement in electron induced molecular oxygen activation reactions under visible light. Consequently, the CCN-P exhibits about 1.5 times higher conversion rate in hydroxylation of phenylboronic acid and over 6-fold faster degradation rate in Rh B organic pollutants photodegradation with respect to pristine carbon nitride. This study provides an in-depth understanding on the optimization of the O2 activation process and the design of advanced photocatalysts.
Anpo, Masakazu,Cheng, Jiajia,Huang, Caijin,Ou, Honghui,Ren, Wei,Wang, Xinchen
p. 636 - 645
(2020/07/27)

Strong Visible-Light-Absorbing Cuprous Sensitizers for Dramatically Boosting Photocatalysis
Developing strong visible-light-absorbing (SVLA) earth-abundant photosensitizers (PSs) for significantly improving the utilization of solar energy is highly desirable, yet it remains a great challenge. Herein, we adopt a through-bond energy transfer (TBET) strategy by bridging boron dipyrromethene (Bodipy) and a CuI complex with an electronically conjugated bridge, resulting in the first SVLA CuI PSs (Cu-2 and Cu-3). Cu-3 has an extremely high molar extinction coefficient of 162 260 m?1 cm?1 at 518 nm, over 62 times higher than that of traditional CuI PS (Cu-1). The photooxidation activity of Cu-3 is much greater than that of Cu-1 and noble-metal PSs (Ru(bpy)32+ and Ir(ppy)3+) for both energy- and electron-transfer reactions. Femto- and nanosecond transient absorption and theoretical investigations demonstrate that a “ping-pong” energy-transfer process in Cu-3 involving a forward singlet TBET from Bodipy to the CuI complex and a backward triplet-triplet energy transfer greatly contribute to the long-lived and Bodipy-localized triplet excited state.
Chen, Kai-Kai,Guo, Song,Li, Xiyou,Liu, Heyuan,Lu, Tong-Bu,Zhang, Zhi-Ming
supporting information
p. 12951 - 12957
(2020/05/29)

Nickel-catalyzed removal of alkene protecting group of phenols, alcohols via chain walking process
An efficient nickel-catalyzed removal of alkene protection group under mild condition with high functional group tolerance through chain walking process has been established. Not only phenolic ethers, but also alcoholic ethers can be tolerated with the retention of stereocenter adjacent to hydroxyl group. The new reaction brings the homoallyl group into a start of new type of protecting group.
Meng, Chenkai,Niu, Haolin,Ning, Juehan,Wu, Wengang,Yi, Jun
(2020/02/04)

FeCl3-catalyzed oxidative decarboxylation of aryl/heteroaryl acetic acids: Preparation of selected API impurities
There is an ever-increasing demand for impurity compounds for use in impurity profiling as regulatory agencies seek information during registration. Herein, we report the FeCl3-catalyzed oxidative decarboxylation of aryl- and heteroaryl acetic acids to the corresponding carbonyl compounds. A variety of useful aldehydes and ketones were prepared in a simple one-pot transformation by employing an environmentally benign, low-cost, and readily available iron salt. The utility of this method has been demonstrated by preparing five valuable API impurities including a multi-gram-scale synthesis of ketorolac impurity B for the first time. This journal is
Gangadurai, Chinnakuzhanthai,Illa, Giri Teja,Reddy, D. Srinivasa
p. 8459 - 8466
(2020/11/05)

Palladium-Catalyzed Hydroxylation of Aryl Halides with Boric Acid
Boric acid, B(OH)3, is proved to be an efficient hydroxide reagent in converting (hetero)aryl halides to the corresponding phenols with a Pd catalyst under mild conditions. Various phenol products were obtained in good to excellent yields. This transformation tolerates a broad range of functional groups and molecules, including base-sensitive substituents and complicated pharmaceutical (hetero)aryl halide molecules.
Song, Zhi-Qiang,Wang, Dong-Hui
supporting information
p. 8470 - 8474
(2020/11/18)

Visible-light-promoted aerobic oxidative hydroxylation of arylboronic acids in water by hydrophilic organic semiconductor
A green and sustainable catalytic system was developed based on perylenediimide (PDI) organic semiconductor for the aerobic oxidative hydroxylation of arylboronic acids in aqueous solution with visible light. By using PDI-SN, a hydrophilic organic semiconductor, which can activate oxygen to produce superoxide radicals in aqueous solution, this reaction proceeds under ambient conditions: water as the solvent and air as the oxidant, giving various phenols as products with high yields. In contrast to methods using organic solvents, this novel process has the potential of green industrial application.
Yu, Kunyi,Zhang, Hanjie,Sheng, Yuqiang,Zhu, Yongfa
supporting information

(2020/06/23)

Cobalt-catalysed selective synthesis of aldehydes and alcohols from esters
Efficient and selective reduction of esters to aldehydes and alcohols is reported in which a simple cobalt pincer catalyst catalyses both transformations using diethylsilane as a reductant. Remarkably, the reaction selectivity is controlled by the stoichiometry of diethylsilane. This journal is
Pattanaik, Sandip,Gunanathan, Chidambaram
supporting information
p. 7345 - 7348
(2020/07/14)

Efficient solvent- And temperature-tuned access to aldoxime ethers and phenolic functions by Pd-catalyzed C-O cross-coupling of aldoximes with aryl bromides and bromo-chalcones
A single method with a functionality switching option was developed for the first time for the Pd-catalyzed C-O cross-coupling of aryl bromides and bromo-chalcones with aldoximes. The ligand tBuXPhos (L2) was found to be an effective supporting ligand for the Pd-catalyzed coupling of aldoximes with bromo coupling partners. The functionality switching from oxime ethers to a phenolic or hydroxy group was driven by solvent or temperature. This method offers the products in good to excellent yields in short reaction times.
Reeta,Rangarajan,Kaushik, Kumar,Singh, Rishi Pal,Singh, Manjula,Singh, Raj Pal
supporting information
p. 1326 - 1336
(2020/02/11)