586-42-5Relevant articles and documents
Palladium aminopyridine complexes catalyzed selective benzylic C-H oxidations with peracetic acid
Bryliakov, Konstantin P.,Lubov, Dmitry P.,Lyakin, Oleg Yu.,Rybalova, Tatyana V.,Samsonenko, Denis G.,Talsi, Evgenii P.
supporting information, p. 11150 - 11156 (2020/09/02)
Four palladium(ii) complexes with tripodal ligands of the tpa family (tpa = tris(2-pyridylmethyl)amine) have been synthesized and X-ray characterized. These complexes efficiently catalyze benzylic C-H oxidation of various substrates with peracetic acid, affording the corresponding ketones in high yields (up to 100%), at 1 mol% catalyst loadings. Complex [(tpa)Pd(OAc)](PF6) with the least sterically demanding ligand tpa demonstrates the highest substrate conversions and ketone selectivities. Preliminary mechanistic data provide evidence in favor of metal complex-mediated rate-limiting benzylic C-H bond cleavage by an electron-deficient oxidant.
Carboxylation of Aryl Triflates with CO2 Merging Palladium and Visible-Light-Photoredox Catalysts
Bhunia, Samir Kumar,Das, Pritha,Nandi, Shantanu,Jana, Ranjan
supporting information, p. 4632 - 4637 (2019/06/27)
We report herein a visible-light-promoted, highly practical carboxylation of readily accessible aryl triflates at ambient temperature and a balloon pressure of CO2 by the combined use of palladium and photoredox Ir(III) catalysts. Strikingly, the stoichiometric metallic reductant is replaced by a nonmetallic amine reductant providing an environmentally benign carboxylation process. In addition, one-pot synthesis of a carboxylic acid directly from phenol and modification of estrone and concise synthesis of pharmaceutical drugs adapalene and bexarotene have been accomplished via late-stage carboxylation reaction. Furthermore, a parallel decarboxylation-carboxylation reaction has been demonstrated in an H-type closed vessel that is an interesting concept for the strategic sector. Spectroscopic and spectroelectrochemical studies indicated electron transfer from the Ir(III)/DIPEA combination to generate aryl carboxylate and Pd(0) for catalytic turnover.
Carboxylation of Aromatic and Aliphatic Bromides and Triflates with CO2 by Dual Visible-Light–Nickel Catalysis
Meng, Qing-Yuan,Wang, Shun,K?nig, Burkhard
supporting information, p. 13426 - 13430 (2017/10/07)
We report the efficient carboxylation of bromides and triflates with K2CO3 as the source of CO2 in the presence of an organic photocatalyst in combination with a nickel complex under visible light irradiation at room temperature. The reaction is compatible with a variety of functional groups and has been successfully applied to the synthesis and derivatization of biologically active molecules. In particular, the carboxylation of unactivated cyclic alkyl bromides proceeded well with our protocol, thus extending the scope of this transformation. Spectroscopic and spectroelectrochemical investigations indicated the generation of a Ni0 species as a catalytic reactive intermediate.
Visible-Light-Driven Carboxylation of Aryl Halides by the Combined Use of Palladium and Photoredox Catalysts
Shimomaki, Katsuya,Murata, Kei,Martin, Ruben,Iwasawa, Nobuharu
supporting information, p. 9467 - 9470 (2017/07/24)
A highly useful, visible-light-driven carboxylation of aryl bromides and chlorides with CO2 was realized using a combination of Pd(OAc)2 as a carboxylation catalyst and Ir(ppy)2(dtbpy)(PF6) as a photoredox catalyst. This carboxylation reaction proceeded in high yields under 1 atm of CO2 with a variety of functionalized aryl bromides and chlorides without the necessity of using stoichiometric metallic reductants.
Oxalic acid as the: In situ carbon monoxide generator in palladium-catalyzed hydroxycarbonylation of arylhalides
Shao, Changdong,Lu, Ailan,Wang, Xiaoling,Zhou, Bo,Guan, Xiaohong,Zhang, Yanghui
supporting information, p. 5033 - 5040 (2017/07/10)
An efficient palladium-catalyzed hydroxycarbonylation reaction of arylhalides using oxalic acid as a CO source has been developed. The reaction features high safety, low catalyst loading, and a broad substrate scope, and provides a safe and tractable approach to access a variety of aromatic carboxylic acid compounds. Mechanistic studies revealed the decomposition pattern of oxalic acid.
Metal-Free Markovnikov-Type Alkyne Hydration under Mild Conditions
Liu, Wenbo,Wang, Haining,Li, Chao-Jun
supporting information, p. 2184 - 2187 (2016/06/01)
A Markovnikov-type alkyne hydration protocol is presented using 20% CF3SO3H (TfOH) as the catalyst under unprecedented mild conditions applicable to various alkynes, including terminal arylalkynes, terminal nonfunctionalized aliphatic alkynes, and internal alkynes with excellent regioselectivity in good to excellent yields (average yields >85%). The reaction procedure operates under mild conditions (25-70°C), with broad functional group compatibility, and uses only slightly more than a stoichiometric amount of water in the absence of any transition metal. The success of this protocol hinges upon the utilization of trifluoroethanol as the solvent.
The method used for the selective demetalization benzylmethacrylic selective hydrogenation catalyst
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Paragraph 0033; 0034; 0035; 0036; 0041; 0042, (2016/12/22)
PROBLEM TO BE SOLVED: To provide a debenzylation technology of efficiently hydrogenating a benzyl group as a protective group without decomposing or hydrogenating a halogen atom and an acyl group in an aromatic halide compound or an aromatic ketone compound.SOLUTION: In a debenzylation method, a hydrogen gas is reacted, in an ester medium, with a carboxylic acid benzyl ester represented by formula (I) in the presence of a β zeolite carrying a palladium ingredient, and a carboxylic acid compound represented by formula (II) is obtained. In the formula: Ar is an aromatic ring group or a heterocyclic group having one or substituents which can be hydrogenated; Zis a single bond, -CHCH- or -CH=CH-; Zis a single bond or -CHCH-; and Bn is a benzyl group.
Application of complementary mass spectrometric techniques to the identification of ketoprofen phototransformation products
Kosjek, Tina,Perko, Silva,Heath, Ester,Kralj, Bogdan,Zigon, Dusan
experimental part, p. 391 - 401 (2011/11/12)
Ketoprofen (KP) is a nonsteroidal anti-inflammatory drug, which during UV irradiation rapidly transforms into benzophenone derivatives. Such transformation products may occur after topical application of KP, which is then exposed to sunlight resulting in a photo-allergic reaction. These reactions are mediated by the benzophenone moiety independently of the amount of allergen. The same reactions will also occur during wastewater or drinking water treatment albeit their effect in the aqueous environment is yet to be ascertained. In addition, only a few such transformation products have been recognised. To enable the detection and structural elucidation of the widest range of KP transformation products, this study applies complementary chromatographic and mass spectrometric techniques including gas chromatography coupled to single quadrupole or ion trap mass spectrometry and liquid chromatography hyphenated with quadrupole-time-of-flight mass spectrometry. Based on structural information gained in tandem and multiple MS experiments, and on highly accurate molecular mass measurements, chemical structures of 22 transformation products are proposed and used to construct an overall breakdown pathway. Among the identified transformation products all but two compounds retained the benzophenone moietya€"a result, which raises important issues concerning the possible toxic synergistic effects of KP and its transformation products. These findings trigger further research into water treatment technologies that would limit their entrance into environmental or drinking waters. Copyright
Hydrogen-bonding-promoted oxidative addition and regioselective arylation of olefins with aryl chlorides
Ruan, Jiwu,Iggo, Jonathan A.,Berry, Neil G.,Xiao, Jianliang
supporting information; experimental part, p. 16689 - 16699 (2011/02/23)
The first, general, and highly efficient catalytic system that allows a wide range of activated and unactivated aryl chlorides to couple regioselectively with olefins has been developed. The Heck arylation reaction is likely to be controlled by the oxidative addition of ArCl to Pd(0). Hence, an electron-rich diphosphine, 4-MeO-dppp, was introduced to facilitate the catalysis. Solvent choice is critical, however; only sluggish arylation is observed in DMF or DMSO, whereas the reaction proceeds well in ethylene glycol at 0.1-1 mol % catalyst loadings, displaying excellent regioselectivity. Mechanistic evidence supports that the arylation is turnover-limited by the oxidative addition step and, most importantly, that the oxidative addition is accelerated by ethylene glycol, most likely via hydrogen bonding to the chloride at the transition state as shown by DFT calculations. Ethylene glycol thus plays a double role in the arylation, facilitating oxidative addition and promoting the subsequent dissociation of chloride from Pd(II) to give a cationic Pd(II)-olefin species, which is key to the regioselectivity observed.
Selective oxidation of acetophenones bearing various functional groups to benzoic acid derivatives with molecular oxygen
Nakamura, Ryota,Obora, Yasushi,Ishii, Yasutaka
experimental part, p. 1677 - 1684 (2011/02/25)
Acetophenones substituted by alkyl, alkoxy, acetoxy, and halogen groups were selectively oxidized with molecular oxygen to the corresponding benzoic acids by using the N,N',N"-trihydroxyisocyanuric acid (THICA)/cobalt(II) acetate [Co(OAc)2] and THICA/Co(OAc)2/manganese(II) acetate.
