10199-67-4Relevant academic research and scientific papers
Sonochemical heating profile for solvents and ionic liquid doped solvents, and their application in the N-alkylation of pyrazoles
Frizzo, Clarissa P.,Bacim, Carolini,Moreira, Dayse N.,Rodrigues, Leticia V.,Zimmer, Geórgia C.,Bonacorso, Hélio G.,Zanatta, Nilo,Martins, Marcos A.P.
, p. 432 - 439 (2016)
The heating profile for 25 solvents was determined in ultrasonic probe equipment at amplitudes of 20%, 25%, and 30%. Each solvent was heated in accordance with its boiling point. The effect of vapor pressure, surface tension, and viscosity of the solvents in dissipated ultrasonic power (Up) was evaluated. Multiple regression analysis of these solvent properties and dissipated Up reveals that solvent viscosity is the property that most strongly affected dissipated Up. Experimentation involving acetonitrile doped with [BMIM][BF4] indicated faster heating than MeCN. Aprotic polar solvents such as DMSO, DMF, and MeCN were tested in the N-alkylation of pyrazoles under ultrasonic conditions. After 5 min at 90 °C, the reactants had been totally converted into product in these solvents. Solvents, with low dissipated Up (e.g., toluene) were tested. Conversions were lower compared to those of aprotic polar solvents. When the reactions were done in hexane, no conversion to product was observed. To check the effect of doping in solvents with low Up, [BMIM][BF4], DMSO, and DMF were selected. The conversions for toluene doped with [BMIM][BF4], DMSO, and DMF were 100%, 59%, and 25%, respectively. These conversions were greater than when done in just toluene (46%). Thus, [BMIM][BF4] was the best polar doping solvent, followed by DMSO. DMF was not considered to be a satisfactory doping solvent. No conversion was observed for reactions in the absence of base performed in DMSO, DMF, and MeCN doped with [BMIM][BF4].
KF/Al2O3-mediated N-alkylation of amines and nitrogen heterocycles and S-alkylation of thiols
Moghaddam, Firouz Matloubi,DokhtTaimoory, Seyedeh Maryam,Ismaili, Hossein,Bardajee, Ghasem Rezanejade
, p. 3599 - 3607 (2006)
KF/Al2O3 efficiently catalyzes N-alkylation of heterocyclic, primary, and secondary amines and S-alkylation of thiols with a variety of alkyl halides. The N-alkylation and S-alkylation adducts were produced in good to excellent yields and in short times. Copyright Taylor & Francis Group, LLC.
Enthalpies of formation of N-substituted pyrazoles and imidazoles
Mo?, Otilia,Ya?n?ez, Manuel,Roux, Mari?a Victoria,Jime?nez, Pilar,Da?valos, Juan Z.,Ribeiro da Silva, Manuel A. V.,Ribeiro da Silva, Maria Das Dores M. C.,Matos, M. Agostinha R.,Amaral, Luisa M. P. F.,Sa?nchez-Migallo?n, Ana,Cabildo, Pilar,Claramunt, Rosa,Elguero, Jose?,Liebman, Joel F.
, p. 9336 - 9344 (1999)
Accurate experimental enthalpies of formation measured using static bomb combustion calorimetry, the "vacuum sublimation" drop calorimetry method, and the Knudsen-effusion method are reported for the first time for four azoles: 1-methylimidazole (1MeIMI), 1-methylpyrazole (1MePYR), 1-benzylimidazole (1BnIMI), and 1-benzylpyrazole (1BnPYR). These values and those corresponding to imidazole (1HIMI), pyrazole (1HPYR), 1-ethylimidazole (1EtIMI), 1-ethylpyrazole (1EtPYR), 1-phenylimidazole (1PhIMI), and 1-phenylpyrazole (1PhPYR) are compared with theoretical values using the G2(MP2) and the B3LYP/6-311*G(3df,2p)//6-31G(d) approaches. In general, there is a very good agreement between calculated and experimental values for the series of N-substituted imidazoles, while the agreement is less good for the series of the N-substituted pyrazoles. Experimentally, the gap between the enthalpies of formation of imidazoles and pyrazoles decreases significantly upon N-substitution, while the theoretical estimates indicate that this decrease is smaller.
Remarkable fast n-alkylation of azaheterocycles under microwave irradiation in dry media
Bogdal, Dariusz,Pielichowski, Jan,Jaskot, Krzysztof
, p. 715 - 722 (1997)
Under microwave irradiation a number of azaheterocycles (i.e., pyrrole, imidazole, pyrazole, indole, and carbazole) react remarkably fast with alkyl halides to give exclusively N-alkyl derivatives.
Transition-metal-free hydrogenation of aryl halides: From alcohol to aldehyde
Zheng, Hong-Xing,Shan, Xiang-Huan,Qu, Jian-Ping,Kang, Yan-Biao
supporting information, p. 5114 - 5117 (2017/11/07)
A transition-metal-and catalyst-free hydrogenation of aryl halides, promoted by bases with either aldehydes or alcohols, is described. One equivalent of benzaldehyde affords an equal yield as that of 0.5 equiv of benzyl alcohol. The kinetic study reveals that the initial rate of PhCHO is much faster than that of BnOH, in the ratio of nearly 4:1. The radical trapping experiments indicate the radical nature of this reaction. Based on the kinetic study, trapping and KIE experiments, and control experiments, a tentative mechanism is proposed. As a consequence, a wide range of (hetero)aryl iodides and bromides were efficiently reduced to their corresponding (hetero)arenes. Thus, for the first time, aldehydes are directly used as hydrogen source instead of other well-established alcohol-hydrogen sources.
A VERSATILE LIGAND FOR PALLADIUM-CATALYZED META-C-H FUNCTIONALIZATIONS
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Page/Page column 93, (2017/11/15)
A class of mono-protected 3-amino-2- hydroxypyridine (MPAHP) ligands that enable the meta- C-H arylation of anilines, phenols, phenylacetic acids, and biologically relevant heterocyclic compounds using norbornene as a transient mediator is disclosed. The applicability of this meta-arylation methodology in the pharmaceutical industry is illustrated for heteroaryl substrates and heteroaryl iodide coupling partners, a feat made possible by using the MPAHP ligand. The enabling nature of MPAHP ligands to achieve other meta-C-H functionalization processes is also illustrated by the development of a meta-C-H amination reaction and a meta-C-H alkynylation reaction.
Synthesizing process of nitrogen-heterocyclic high-selectivity aldehyde
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Paragraph 0014; 0017; 0018; 0030; 0034; 0043; 0046, (2017/09/05)
The invention relates to a synthesizing process of nitrogen-heterocyclic high-selectivity aldehyde. The synthesizing process is characterized in that when nitrogen-heterocyclic nitrogen atoms have hydrogen atoms, pyrrole, piperidine and pyrazole are used as the initial raw materials, and the pyrrole, the piperidine and the pyrazole are allowed to have reaction with piperidine-1-formaldehyde under nitrogen atom protection to obtain required nitrogen-atom ortho-position aldehyde; when nitrogen-heterocyclic nitrogen atoms have no hydrogen atoms, pyridine and pyrimidine are used to have reaction with the piperidine-1-formaldehyde to obtain the required nitrogen-atom ortho-position aldehyde. The synthesizing process is simple to operate, few in steps and high in selectivity and is a universal method using nitrogen heterocycle to synthesize the nitrogen ortho-position aldehyde.
Radical Hydrodeiodination of Aryl, Alkenyl, Alkynyl, and Alkyl Iodides with an Alcoholate as Organic Chain Reductant through Electron Catalysis
Dewanji, Abhishek,Mück-Lichtenfeld, Christian,Studer, Armido
supporting information, p. 6749 - 6752 (2016/06/09)
A simple and efficient method for radical hydrodeiodination is reported. The novel approach uses electron catalysis. In situ generated Na-alcoholates are introduced as radical chain reducing reagents and reactions work with O2as cheap initiator. Hydrodeiodination works on aryl, alkenyl, alkynyl iodides and a tert-alkyl iodide also gets reduced applying the method. Albeit less general, the method is also applicable to the reduction of aryl bromides. The novel reagent is successfully used to conduct typical reductive radical cyclization reactions and mechanistic studies are reported.
N-Picolinamides as ligands for Ullmann-type C-N coupling reactions
Damkaci, Fehmi,Alawaed, Abdulkhaliq,Vik, Erik
supporting information, p. 2197 - 2200 (2016/05/02)
The use of N-phenyl-2-pyridincarboxamide-1-oxide as a ligand with Cu2O in Ullmann type C-N bond formations between aryl halides and N-heteroaryls in common solvents, such as MeCN, DMF, and DMSO at 82-120 °C has been successfully demonstrated. The ligand is effective when only 4% equiv is used relative to the substrate. The reaction provided the corresponding products in coupling of electron-rich, electron poor, and ortho-substituted aryl halides, including ortho aryl-chlorides, in good to very good yields. N-arylation is selectively preferred at the benzyl position when ortho-halide benzyl bromide is reacted with one equivalent of pyrazole. However, di-N-arylation is achieved in very high yields when 2.5 equiv of pyrazole is used, providing a stoichiometric control over the coupling reaction.
Ligand-Promoted Meta-C-H Arylation of Anilines, Phenols, and Heterocycles
Wang, Peng,Farmer, Marcus E.,Huo, Xing,Jain, Pankaj,Shen, Peng-Xiang,Ishoey, Mette,Bradner, James E.,Wisniewski, Steven R.,Eastgate, Martin D.,Yu, Jin-Quan
supporting information, p. 9269 - 9276 (2016/08/05)
Here we report the development of a versatile 3-acetylamino-2-hydroxypyridine class of ligands that promote meta-C-H arylation of anilines, heterocyclic aromatic amines, phenols, and 2-benzyl heterocycles using norbornene as a transient mediator. More than 120 examples are presented, demonstrating this ligand scaffold enables a wide substrate and coupling partner scope. Meta-C-H arylation with heterocyclic aryl iodides as coupling partners is also realized for the first time using this ligand. The utility for this transformation for drug discovery is showcased by allowing the meta-C-H arylation of a lenalidomide derivative. The first steps toward a silver-free protocol for this reaction are also demonstrated.
