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• 1739-84-0 1,2-dimethyl-1H-imidazole 
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• 99-90-1 para-bromoacetophenone 

Relevant academic research and scientific papers

Well-defined palladium(0) complexes bearing N-heterocyclic carbene and phosphine moieties: Efficient catalytic applications in the Mizoroki-Heck reaction and direct C-H functionalization

Two series of well-defined palladium(0) complexes with phosphine-functionalized N-heterocyclic carbene ligands were prepared. These complexes featured six- and seven-membered chelate rings in the two series. Among the seven-membered chelate complexes, those featuring the PCy2 moiety exhibited observable fluxional behavior on the NMR time scale, corresponding to the interchange between two sets of conformations. Most of these novel complexes were successfully structurally characterized by single-crystal X-ray diffraction studies. These two series of palladium(0) complexes were tested for their potential catalytic applications in two mechanistically distinct reactions, namely, Mizoroki-Heck coupling and direct C-H functionalization reactions. One of the six-membered chelate complexes was found to be an efficient pre-catalyst for mediating the coupling reactions between aryl chlorides and alkenes. The palladium(0) complex could also be effectively applied in the direct C-H functionalization reactions of aryl bromides with 1,2-dimethylimidazole.

Method for catalyzing direct arylation of imidazole compound by using palladium complex

The invention relates to a method for catalyzing direct arylation of an imidazole compound by using a palladium complex, which comprises the following steps: in the presence of alkali, taking the imidazole compound and aryl halide as raw materials, taking

Regioselective C-H arylation of imidazoles employing macrocyclic palladium(II) complex of organoselenium ligand

In this report we have presented synthesis of a new air stable bidentate selenium ligand (L1) by the reaction of 1,8-bis(2-(chloromethyl)phenoxy)octane with sodium salt of diphenyl diselenide. The reaction of bidentate selenium ligand (L1) with Pd(CH

Palladium-Based Catalysts Supported by Unsymmetrical XYC–1 Type Pincer Ligands: C5 Arylation of Imidazoles and Synthesis of Octinoxate Utilizing the Mizoroki–Heck Reaction

A series of new unsymmetrical (XYC–1 type) palladacycles (C1–C4) were designed and synthesized with simple anchoring ligands L1–4H (L1H = 2-((2-(4-methoxybenzylidene)-1-phenylhydrazinyl)methyl)pyridine, L2H = N,N-dimethyl-4-((2-phenyl-2-(pyridin-2-ylmethyl)hydrazono)methyl)aniline, L3H = N,N-diethyl-4-((2-phenyl-2-(pyridin-2-ylmethyl)hydrazono)methyl) aniline and L4H = 4-(4-((2-phenyl-2-(pyridin-2-ylmethyl)hydrazono) methyl)phenyl)morpholine H = dissociable proton). Molecular structure of catalysts (C1–C4) were further established by single X-ray crystallographic studies. The catalytic performance of palladacycles (C1–C4) was explored with the direct Csp2–H arylation of imidazoles with aryl halide derivatives. These palladacycles were also applied for investigating of Mizoroki–Heck reactions with aryl halides and acrylate derivatives. During catalytic cycle in situ generated Pd(0) nanoparticles were characterized by XPS, SEM and TEM analysis and possible reaction pathways were proposed. The catalyst was employed as a pre-catalyst for the gram-scale synthesis of octinoxate, which is utilized as a UV-B sunscreen agent.

Dimetallic Palladium-NHC Complexes: Synthesis, Characterization, and Catalytic Application for Direct C?H Arylation Reaction of Heteroaromatics with Aryl Chlorides

A series of dimetallic palladium(II)-NHC complexes comprised of 1,4-naphthalenyl or 9,10-anthracenyl spacer sandwiched between two imidazole rings was successfully synthesized. These complexes were characterized by 1H and 13C{1H} NMR spectroscopy and elemental analysis. The structures of two dimetallic palladium complexes and a related mononuclear palladium complex to be used for comparative studies were further characterized by X-ray diffraction. The dimetallic palladium complex with the 9,10-anthracenyl linker was very efficient in catalyzing direct C?H arylation reactions of heteroaromatic compounds (imidazoles, imidazo[1,2-a]pyridine, and thioazole) with a broad range of aryl chlorides, employing a mild monopalladium loading of 1.5 mol%.It allows for the effective use of aryl chlorides to prepare arylated heterocycles, previously only accessible with the more reactive bromide counterparts. Importantly, the catalytic activity of the dimetallic precatalyst was found to be higher than that of an analogous mononuclear complex. (Figure presented.).

Palladium Complexes of Thio/Seleno-Ether Containing N-Heterocyclic Carbenes: Efficient and Reusable Catalyst for Regioselective C-H Bond Arylation

The synthesis of the novel S,CNHC type half-pincer ligand precursors (L1 and L2) is described herein by using the atom economy reactions of 1-(2-(phenylthio)ethyl)-1H-imidazole with benzyl bromide and bromodiphenylmethane, respectively. The analogous reaction of 1-(2-(phenylselanyl)ethyl)-1H-imidazole with 2-bromoethyl phenyl sulfide has also resulted in a imidazolium bromide (L3) which is a precursor of novel S,CNHC,Se type pincer ligand. The route of silver-NHC transmetalation was employed to get the palladium complexes [Pd(L1/L2–HBr)Cl2] (C1 and C2) and [Pd(L3–HBr)Cl]BF4 (C3). The imidazolium bromide (L1–L3) and palladium complexes (C1–C3) were characterized by using multinuclear NMR and HR-MS. The structure and bonding in the complexes C1 and C2 were validated by X-ray crystallography. Thermally robust and moisture/air insensitive palladium complexes C1–C3 have been explored in the catalysis of C–H bond arylation of imidazoles. The protocol operates under mild reaction conditions in air with an excellent regioselective C–H bond arylation at C-5 position in imidazoles. All the complexes were found to be efficient (yield up to 97 % in 12 h) in the catalysis; however, the activating pincer ligand framework containing Pd catalyst C3, was found to be utmost effective among the three catalysts. Only 0.5 mol-% catalyst loading is required to achieve admirable yield of the desired cross-coupled products. A wide range of substrates was examined, and the developed protocol was applicable to all derivatives with high functional group tolerance and greater efficiency. More importantly, the catalyst C3 has also been found recyclable up to five cycles with minor decrease in efficiency which is highly desirable feature for the development of economical and sustainable industrial reaction processes. The PPh3 and Hg poisoning tests have established the complete homogeneous nature of the catalysis.

A tridentate CNO-donor palladium(II) complex as efficient catalyst for direct C―H arylation: Application in preparation of imidazole-based push–pull chromophores

A series of imidazolium chlorides for the formation of tridentate CNO-donor palladium(II) complexes featuring N-heterocyclic carbene moieties have been developed from cheap and readily available starting materials with high yields. Their palladium complex

Palladium(II) Complexes of N-Heterocyclic Carbene Amidates Derived from Chalcogenated Acetamide-Functionalized 1 H-Benzimidazolium Salts: Recyclable Catalyst for Regioselective Arylation of Imidazoles under Aerobic Conditions

The chalcogenated acetamide-functionalized 1H-benzimidazolium salt precursors [1-(CH2C(O)NH(CH2)2S/SePh)-3-R-C7H5N2]+ X (L1-L4; R = Me, CH2Ph; X = Br, I) to C,N,S/Se l

Sterically Encumbered Tetraarylimidazolium Carbene Pd-PEPPSI Complexes: Highly Efficient Direct Arylation of Imidazoles with Aryl Bromides under Aerobic Conditions

A series of sterically encumbered tetraarylimidazolium carbene Pd-PEPPSI complexes were conveniently prepared and fully characterized. These sterically encumbered Pd-PEPPSI complexes act as active precatalysts for the direct arylation of imidazoles with aryl bromides under aerobic conditions. The catalytic performance of Pd-PEPPSI complexes in cross-coupling processes is investigated. Under the optimal protocols, the cross-coupling reactions regioselectively produced C5-arylation products in moderate to excellent yields, which could tolerate a wide range of functional aryl bromides.

Direct C5-arylation reaction between imidazoles and aryl chlorides catalyzed by palladium complexes with phosphines and N-heterocyclic carbenes

Palladium(II) acetate complexes bearing phosphines and carbene ligands, Pd(L)(PR3)(OAc)2 (1a, R = Ph; 1b, R = Cy; L = 1,3-dibenzylimidazol-2-ylidene), were prepared by salt metathesis reactions of their chloro complexes with AgOAc in good yields. The electron-rich 1b was efficient in catalyzing C-5 direct arylation of imidazoles with aryl halides. Most significantly, the catalytic system allows a range of aryl chlorides as substrates. Microwave irradiation effectively promotes the reactions, with good yields obtainable in only 2 h. In combination with the classical method of C-C bond formation reactions, novel imidazole derivatives featuring biaryl and styryl subunits were successfully obtained from 1,4-dichlorobenzene and 1-bromo-4-chlorobenzene.