- ENAMINES. 8. POLAROGRAPHIC STUDY OF THE REACTIONS OF A NUMBER OF ENAMINO KETONES WITH NUCLEOPHILIC REAGENTS
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The hydrolysis and hydrazinolysis of cyclic enamino ketones of the pyrrolidine, piperidine, and hexahydroazepine series, as well as their noncyclic analogs, were investigated.It is shown that these processes have several principles in common.A bell-shaped
- Kiselev, S. S.,Polievktov, M. K.,Granik, V. G.
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- Copper(I)-Catalyzed Oxyamination of β,γ-Unsaturated Hydrazones: Synthesis of Dihydropyrazoles
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An efficient aerobic copper(I)-catalyzed oxyamination of β, γ-unsaturated hydrazones has been developed. The methodology provides effective access to dihydropyrazole derivatives in a one-pot process utilizing dioxygen as a sustainable sacrificial oxidant.
- Chen, Shanshan,Chen, Wenming,Chen, Xu,Chen, Guifang,Ackermann, Lutz,Tian, Xu
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- Highly Efficient Cuprous Complexes with Thermally Activated Delayed Fluorescence for Solution-Processed Organic Light-Emitting Devices
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Two mononuclear cuprous complexes [Cu(PNNA)(POP)]BF4 (1) and [Cu(PNNA)(Xantphos)]BF4 (2) (PNNA = 9,9-dimethyl-10-(6-(3-phenyl-1H-pyrazol-1-yl)pyridin-3-yl)-9,10-dihydroacridine, POP = bis[2-(dipenylphosphino)phenyl]ether, Xantphos =4
- Liang, Dong,Chen, Xu-Lin,Liao, Jian-Zhen,Hu, Jin-Yu,Jia, Ji-Hui,Lu, Can-Zhong
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Read Online
- Photoelectric properties of aromatic triangular tri-palladium complexes and their catalytic applications in the Suzuki-Miyaura coupling reaction
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The photoelectric properties and catalytic activities of substituted triphenylphosphine and sulfur/selenium ligand supported aromatic triangular tri-palladium complexes1-4, abbreviated as [Pd3]+, were investigated. The cyclic voltammogram of [Pd3]+in CH3CN-nBu4NPF6showed a single quasi-reversible wave which was consistent with their robust property and provided preliminary proof for their electron transfer processes in catalysis. With excitation at 267 nm, [Pd3]+exhibited strong ratiometric fluorescence at 550 and 780 nm at a temperature gradient from 77 K to 287 K. These peculiar triangular tri-palladium complexes showed excellent catalytic activities and exclusive reactivity with aryl iodides over the other halogenated aromatics in the Suzuki-Miyaura coupling reaction. The electronic and steric hindrance effects of substituents on the aryl iodides and aryl boronic acids including heteroaromatics like pyridine, pyrazine and thiophenes were explored and most substrates achieved up to 99% of yields. (2-[1,1′-Biphenyl]-2-ylbenzothiazole) which was analogous to the selective cyclooxygenase-2 (COX-2) inhibitors was also synthesized with our tri-palladium catalyst and gave good isolated yield (94%). The study of the catalytic process revealed that the mechanism of the reaction may involve the replacement of the sulphur ligand on [Pd3]+by iodine from aryl iodides, which was beneficial for the matching of C-I bond energy.
- Li, Jia,Li, Xujun,Liu, Xiang,Maestri, Giovanni,Malacria, Max,Wang, Xiaoshuang,Wang, Yanlan,Wu, Lingang
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supporting information
p. 11834 - 11842
(2021/09/06)
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- Transition metal free, green and facile halogenation of ketene dithioacetals using a KX-oxidant system
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A facile oxidative halogenation of α-oxo ketene dithioacetals is achieved by using a potassium halide and oxidant combination under transition metal free conditions at ambient temperature. Using this methodology, halogenated ketene dithioacetals are synth
- Rai, Vishakha,Sorabad, Ganesh Shivayogappa,Maddani, Mahagundappa Rachappa
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p. 1109 - 1113
(2021/01/25)
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- Preparation method of pyrazole derivative (by machine translation)
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The preparation method comprises the following steps: mixing an alkyne propyl alcohol derivative, a halogen source, an acid and a solvent, heating and reacting, and reacting to Meyer - Schuster generate the pyrazole derivative. Compared with the prior art, the preparation method disclosed by the invention has 91% the advantages of maximum yield, simple operation, mild conditions, high conversion rate, few byproducts and the like, and provides a brand-new synthetic method for construction of pyrazole compounds. (by machine translation)
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Paragraph 0116-0120
(2019/12/02)
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- Ruthenium-catalyzed formation of pyrazoles or 3-hydroxynitriles from propargyl alcohols and hydrazines
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Functionalized pyrazoles are generated from secondary propragyl alcohols and hydrazines in a ruthenium-catalyzed cascade process, consisting of redox isomerization, Michael addition, cyclocondensation and dehydrogenation steps. The same bifunctional catalyst mediates the conversion of tertiary propargyl alcohols with hydrazine to 3-hydroxynitriles via anti-Markovnikov hydroamination followed by elimination of ammonia.
- Kaufmann, Julia,J?ckel, Elisabeth,Haak, Edgar
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supporting information
p. 91 - 101
(2019/07/09)
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- Palladium catalyzed hydrodefluorination of fluoro-(hetero)arenes
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Palladium catalyzed hydrodefluorination was developed for fine-tuning the properties of fluoro-(hetero)aromatic compounds. The robust reaction can be set up in air, requires only commercially available components, and tolerates a variety of heterocycles and functionalities relevant to drug discovery. Given the prevalence of fluorine incorporation around metabolic hotspots, the corresponding deuterodefluorination reaction may prove useful for converting fluorinated libraries to deuterated analogues to suppress the oxidative metabolism by kinetic isotope effects.
- Gair, Joseph J.,Grey, Ronald L.,Giroux, Simon,Brodney, Michael A.
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supporting information
p. 2482 - 2487
(2019/04/10)
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- Molybdenum-silver co-catalyzed cycloaddition of alkynes with: N -isocyanoiminotriphenylphosphorane (NIITP): An efficient strategy for the synthesis of monosubstituted pyrazoles
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A new molybdenum-silver co-catalyzed [3+2] cycloaddition of alkynes with N-isocyanoiminotriphenylphosphorane (NIITP) has been described. The NIITP serves as a non-toxic, facile "CNN" source. Over 30 substrates were successfully converted to the desired compounds in good to excellent yields.
- Mi, Pengbing,Lang, Jiajia,Lin, Shaojian
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supporting information
p. 7986 - 7989
(2019/07/10)
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- Preparing method for monosubstituted pyrazole compound
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The invention belongs to the field of chemical synthesis, and particularly relates to a preparing method for a monosubstituted pyrazole compound. The preparing method includes the following steps thatunder catalysis of a molybdenum compound, an alkyne compound and N-isocyano triphenyl phosphinimine react in an organic solvent, and the monosubstituted pyrazole compound is obtained. The alkyne compound is of a structure in a formula (I), and the monosubstituted pyrazole compound is of a structure in a formula (II), wherein R is alkyl or substitution alkyl or aryl or substitution aryl or heteroaryl or substitution heteroaryl. According to the method, the alkyne compound and the N-isocyano triphenyl phosphinimine serve as reaction substrates, the molybdenum compound serves as a catalyst, anda series of monosubstituted pyrazole compounds can be synthesized by adjusting the specific type of the alkyne compound. The method is easy to operate, the raw materials and reagents are easy to obtain, and the method is mild in condition, environmentally friendly and particularly suitable for large-scale industrial production.
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Paragraph 0057-0064
(2019/10/01)
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- Silver-Mediated [3 + 2] Cycloaddition of Alkynes and N-Isocyanoiminotriphenylphosphorane: Access to Monosubstituted Pyrazoles
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A silver-mediated [3 + 2] cycloaddition of "CNN" and "C≡C" for constructing pyrazoles has been described. The "CNN" building block used is N-isocyanoiminotriphenylphosphorane, which is a stable, safe, easy-to-handle, and odorless solid isocyanide. The reaction is characterized by its mild conditions, broad substrate scope, and excellent functional group tolerance.
- Yi, Fanhua,Zhao, Wanjun,Wang, Zikun,Bi, Xihe
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supporting information
p. 3158 - 3161
(2019/05/10)
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- A base-promoted cascade reaction of α,β-unsaturated: N -tosylhydrazones with o -hydroxybenzyl alcohols: Highly regioselective synthesis of N-sec -alkylpyrazoles
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An efficient method for the synthesis of N-sec-alkylpyrazoles through a base-promoted cascade cyclization/Michael addition reaction of α,β-unsaturated N-tosylhydrazones with ortho-hydroxybenzyl alcohols has been developed. The desired products containing di- or triaryl groups at the same carbon atom were afforded in good to excellent yields with excellent regioselectivities (>20:1). Moreover, a three-component reaction of ortho-hydroxybenzyl alcohols, α,β-unsaturated N-tosylhydrazones and saturated N-tosylhydrazones also took place to afford pyrazoles in good yields. This reaction offers a new route to triarylmethanes with a simple operation and is applicable for large-scale synthesis.
- Chen, Lian-Mei,Zhao, Juan,Xia, An-Jie,Guo, Xiao-Qiang,Gan, Ya,Zhou, Chuang,Yang, Zai-Jun,Yang, Jun,Kang, Tai-Ran
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supporting information
p. 8561 - 8570
(2019/10/02)
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- Ruthenium(II)-Catalyzed C?C Arylations and Alkylations: Decarbamoylative C?C Functionalizations
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Ruthenium(II)biscarboxylate catalysis enabled selective C?C functionalizations by means of decarbamoylative C?C arylations. The versatility of the ruthenium(II) catalysis was reflected by widely applicable C?C arylations and C?C alkylations of aryl amides
- Moselage, Marc,Li, Jie,Kramm, Frederik,Ackermann, Lutz
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supporting information
p. 5341 - 5344
(2017/04/27)
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- COMPOUNDS AND METHODS FOR HEMATOPOIETIC REGENERATION
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The invention relates to compounds that promote hematopoietic regeneration. The invention further relates to methods of promoting hematopoietic regeneration using the novel compounds of the invention.
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Page/Page column 36-37
(2017/12/29)
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- Zinc-promoted cyclization of tosylhydrazones and 2-(dimethylamino)malononitrile: An efficient strategy for the synthesis of substituted 1-tosyl-1: H -pyrazoles
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A Zn(OTf)2-promoted cyclization reaction of tosylhydrazones with 2-(dimethylamino)malononitrile has been successfully developed providing an efficient strategy for the synthesis of substituted 1-tosyl-1H-pyrazoles.
- Zhang, Bang-Hong,Lei, Lin-Sheng,Liu, Si-Zhan,Mou, Xue-Qing,Liu, Wei-Ting,Wang, Shao-Hua,Wang, Jie,Bao, Wen,Zhang, Kun
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supporting information
p. 8545 - 8548
(2017/08/04)
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- Calcium carbide as the acetylide source: Transition-metal-free synthesis of substituted pyrazoles via [1,5]-sigmatropic rearrangements
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Under transition-metal-free conditions, calcium carbide was used as the acetylide source to react with a wide range of N-tosylhydrazones derived from aldehydes or ketones, affording various substituted pyrazoles in good yields with high regioselectivities. The transformations go through [3 + 2] cycloadditions followed by [1,5]-sigmatropic rearrangements, which are supported by deuterium-labeling experiments.
- Yu, Yue,Huang, Wei,Chen, Yang,Gao, Bingjie,Wu, Wanqing,Jiang, Huanfeng
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supporting information
p. 6445 - 6449
(2018/06/08)
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- A facile and expeditious approach to substituted 1H-pyrazoles catalyzed by iodine
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A facile and expeditious method for the synthesis of 1H-pyrazoles by the reaction of α,β-unsaturated aldehydes/ketones and sulfonyl hydrazide catalyzed by as low as 2 mol % I2 has been demonstrated. This synthetic system features simple operation and mild reaction conditions, and displays a broad functional group tolerance furnishing good to excellent yields.
- Zhang, Hailei,Wei, Qian,Zhu, Guodong,Qu, Jingping,Wang, Baomin
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supporting information
p. 2633 - 2637
(2016/06/01)
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- Novel crown ether functionalized imidazolium-based acidic ionic liquid catalyzed synthesis of pyrazole derivatives under solvent-free conditions
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Abstract An innovatively designed novel crown ether functionalized imidazolium-based reusable acidic ionic liquid [crown ether MIm] [HSO4] has been efficiently implemented for the synthesis of pyrazole derivatives using various substituted enaminones, hydrazine hydrate and phenyl hydrazine under solvent-free conditions. Structural novelty and task efficiency of the catalyst, high yields of desired products, greener approach attributing high atom economy and solvent-free conditions render this protocol suitable to cope with the current demand in contemporary organic chemistry. The inventive idea of utilizing crown ether functionalized ionic liquid as a catalyst was for the first time demonstrated in this protocol.
- Patil, Dayanand,Chandam, Dattatraya,Mulik, Abhijeet,Jagdale, Suryabala,Patil, Prasad,Deshmukh, Madhukar
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p. 6843 - 6858
(2015/08/18)
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- Discovery of Potent and Selective RSK Inhibitors as Biological Probes
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While the p90 ribosomal S6 kinase (RSK) family has been implicated in multiple tumor cell functions, the full understanding of this kinase family has been restricted by the lack of highly selective inhibitors. A bis-phenol pyrazole was identified from hig
- Jain, Rama,Mathur, Michelle,Lan, Jiong,Costales, Abran,Atallah, Gordana,Ramurthy, Savithri,Subramanian, Sharadha,Setti, Lina,Feucht, Paul,Warne, Bob,Doyle, Laura,Basham, Stephen,Jefferson, Anne B.,Lindvall, Mika,Appleton, Brent A.,Shafer, Cynthia M.
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p. 6766 - 6783
(2015/09/22)
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- Base-promoted coupling of carbon dioxide, amines, and N-tosylhydrazones: A novel and versatile approach to carbamates
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A base-promoted three-component coupling of carbon dioxide, amines, and N-tosylhydrazones has been developed. The reaction is suggested to proceed via a carbocation intermediate and constitutes an efficient and versatile approach for the synthesis of a wide range of organic carbamates. The advantages of this method include the use of readily available substrates, excellent functional group tolerance, wide substrate scope, and a facile work-up procedure.
- Xiong, Wenfang,Qi, Chaorong,He, Haitao,Ouyang, Lu,Zhang, Min,Jiang, Huanfeng
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supporting information
p. 3084 - 3087
(2015/05/12)
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- Selective palladium-catalyzed direct C-H arylation of unsubstituted N-protected pyrazoles
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A highly selective C-5 arylation of N-dimethylaminosulfamoyl-protected pyrazole with aryl bromides is catalyzed by 2-5 mol% palladium in the presence of triphenylphosphine ligand and carboxylic acid additive. Selectivities up to 45:1 (C-5:C-4) can be achieved by running the reaction in non-polar solvents. A thorough study of scope and limitations shows good general tolerance of aryl bromide substitution. However, limitations on tolerance of ortho-subsitution and protic functional groups were established. Together with a telescoped deprotection step this method presents a viable alternative for the synthesis of C-3 arylated pyrazole building blocks.
- Kumpulainen, Esa T. T.,Pohjakallio, Antti
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supporting information
p. 1555 - 1561
(2014/06/09)
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- One-pot oxidation and rearrangement of propargylamines and in situ pyrazole synthesis
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Reported here are procedures for a one-pot oxidation and rearrangement of propargylamines to synthesize enaminones, with supporting mechanistic studies. Also reported are the extended one-pot syntheses of pyrazoles, including celecoxib and various heterocyclic compounds.
- Chen, Jinshan,Properzi, Roberta,Uccello, Daniel P.,Young, Jennifer A.,Dushin, Russell G.,Starr, Jeremy T.
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p. 4146 - 4149
(2014/09/29)
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- The reaction of dimethylalkynylaluminum reagents with trimethylsilyldiazomethane: Original reactivity leading to new α-Silylated Alkynyl Hydrazones
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Trimethylsilyl (TMS) diazomethane does not react as a homologating reagent but as a C-electrophilic species with dimethylalkynylaluminum reagents. This unprecedented reactivity enables a simple access to unusual α-silylated alkynyl hydrazones.
- Kumar, Rahul,Turcaud, Serge,Micouin, Laurent
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supporting information
p. 6192 - 6195
(2015/01/09)
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- Efficient one-pot synthesis of substituted pyrazoles
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An efficient, one-pot synthesis of substituted pyrazoles from enones, hydrazides, and halides was developed. In comparison with the classical Knorr pyrazole synthesis, this methodology gave a different type of product (R 3≥R5). A range of substituted pyrazoles were prepared in good to high yields with complete regioselectivity.
- Tang, Meng,Zhang, Fu-Min
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p. 1427 - 1433
(2013/02/25)
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- Trinuclear diamagnetic nickel(II) complexes with bridging 3-arylpyrazolato ligands
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Orange-red trinuclear nickel(II) complexes are obtained by reacting Ni(ClO4)2(H2O)6 with 3(5)-arylpyrazoles in the presence of a base. Herein, the diamagnetic nickel centers are coordinated in a square-pyramidal manner by four pyrazolato ligands, each of which bridges two nickel sites. The structurally unique complexes were investigated by NMR, IR, fluorescence, and X-ray spectroscopy. All seven compounds described here were structurally elucidated by single-crystal X-ray diffraction. With 3(5)-ferrocenylpyrazole as the substrate, a nonametallic system that possesses six redox-active ferrocenyl moieties was obtained. The reactions of Ni(ClO4)2(H2O)6 with 3(5)-arylpyrazoles in the presence of a base lead to pyrazolate-bridged trinuclear nickel(II) complexes. This strategy allows the introduction of a broad variety of aromatic substituents such as redox-active sites or additional phosphine donors in the periphery of the trinuclear core. Copyright
- Salih, Kifah S. M.,Bergner, Susann,Kelm, Harald,Sun, Yu,Gruen, Anneken,Schmitt, Yvonne,Schoch, Roland,Busch, Mark,Deibel, Naina,Braese, Stefan,Sarkar, Biprajit,Bauer, Matthias,Gerhards, Markus,Thiel, Werner R.
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p. 6049 - 6059
(2014/01/06)
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- Synthesis of pinacol arylboronates from aromatic amines: A metal-free transformation
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A metal-free borylation process based on Sandmeyer-type transformation using arylamines derivatives as the substrates has been developed. Through optimization of the reaction conditions, this novel conversion can be successfully applied to a wide range of aromatic amines, affording borylation products in moderate to good yields. Various functionalized arylboronates, which are difficult to access by other methods, can be easily obtained with this metal-free transformation. Moreover, this transformation can be followed by Suzuki-Miyaura cross-coupling without purification of the borylation products, which enhances the practical usefulness of this method. A possible reaction mechanism involving radical species has been proposed.
- Qiu, Di,Jin, Liang,Zheng, Zhitong,Meng, He,Mo, Fanyang,Wang, Xi,Zhang, Yan,Wang, Jianbo
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p. 1923 - 1933
(2013/03/29)
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- PHARMACEUTICAL COMPOUNDS
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The invention relates to compounds and compositions for inhibiting the enzyme fatty acid amide hydrolase (FAAH), the use of the compounds in therapy and, in particular, for treating or preventing conditions whose development or symptoms are linked to subs
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Page/Page column 30
(2012/03/27)
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- Unexpected C-C bond cleavage: A route to 3,6-diarylpyridazines and 6-arylpyridazin-3-ones from 1,3-dicarbonyl compounds and methyl ketones
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An unexpected C-C bond cleavage has been revealed in the absence of metal. This observation has been exploited to develop an efficient approach toward 3,6-diarylpyridazines and 6-arylpyridazin-3-ones from simple and commercially available 1,3-dicarbonyl compounds and methyl ketones.
- Gao, Qinghe,Zhu, Yanping,Lian, Mi,Liu, Meicai,Yuan, Jingjing,Wu, Anxin,Yin, Guodong
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supporting information
p. 9865 - 9870,6
(2012/12/12)
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- One-pot formation of aza-enolates from secondary amines and condensation to esters and alkyl bromides
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Starting from commercial secondary amines, a one-pot procedure allows a direct access to enaminones through a one-pot deprotonation/oxidation/in situ re-deprotonation/acylation sequence without intermediate isolation of the intermediate Schiff base or its corresponding enamine tautomer. An alternative one-pot sequence involving a similar oxidation step followed by one or two alkylation steps yields, after acidic work-up, functionalized ketones directly from the parent amine. This process has been applied to an expeditious synthesis of the male aggregation pheromone of the cereal leaf beetle Oulema melanopus.
- Chevalley, Alice,Férézou, Jean-Pierre
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experimental part
p. 5882 - 5889
(2012/09/11)
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- Synthesis of substituted 1 H-indazoles from arynes and hydrazones
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The 1H-indazole skeleton can be constructed by a [3 + 2] annulation approach from arynes and hydrazones. Under different reaction conditions, both N-tosylhydrazones and N-aryl/alkylhydrazones can be used to afford a variety of indazoles. The former reaction affords 3-substituted indazoles either via in situ generated diazo compounds or through an annulation/elimination process. The latter reaction leads to 1,3-disubstituted indazoles likely through an annulation/oxidation process. The reactions operate under mild conditions and can accommodate aryl, vinyl, and less satisfactorily, alkyl groups.
- Li, Pan,Wu, Chunrui,Zhao, Jingjing,Rogness, Donald C.,Shi, Feng
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experimental part
p. 3149 - 3158
(2012/07/14)
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- Palladium-catalyzed carbonylative heck reaction of aryl bromides with vinyl ethers to 3-alkoxy alkenones and pyrazoles
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Three COming together: The first carbonylative Heck coupling reaction of aryl bromides and vinyl ethers leading to 1-aryl-3-alkoxy-2-propen-1-ones has been established (see scheme). Based on this coupling methodology, a novel one-pot synthesis of aryl-substituted pyrazoles was also realized. Copyright
- Schranck, Johannes,Wu, Xiao-Feng,Neumann, Helfried,Beller, Matthias
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supporting information; experimental part
p. 4827 - 4831
(2012/05/20)
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- Synthesis of 3-substituted indazoles from arynes and N-tosylhydrazones
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Readily available, stable, and inexpensive N-tosylhydrazones react with arynes under mild reaction conditions to afford 3-substituted indazoles in moderate to good yields. The reaction appears to involve a dipolar cycloaddition of in situ generated diazo
- Li, Pan,Zhao, Jingjing,Wu, Chunrui,Larock, Richard C.,Shi, Feng
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supporting information; experimental part
p. 3340 - 3343
(2011/09/12)
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- A simple and efficient synthesis of pyrazoles in water
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A simple, highly efficient, and environmentally friendly method for the synthesis of substituted 1H-pyrazoles by one-pot condensation reaction of α,β-unsaturated carbonyl compounds with tosyl hydrazide in water was developed. The reaction system exhibited tolerance with various functional groups, Aromatic moiety with both electron-rich and electron-deficient substituents could give desired products in good to excellent yields.
- Wen, Jun,Fu, Yun,Zhang, Ruo-Yi,Zhang, Ji,Chen, Shan-Yong,Yu, Xiao-Qi
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supporting information; experimental part
p. 9618 - 9621
(2011/12/14)
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- An efficient solvent-free synthesis of NH-pyrazoles from β-dimethylaminovinylketones and hydrazine on grinding
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A series of NH-pyrazoles was efficiently synthesized from the reaction of β-dimethylaminovinylketones ([R1C(O)C(R2){double bond, long}CHN(Me2)], where R1 = Me, Ph, 3-MeO-Ph, 4-Me-Ph, 4-MeO-Ph, 4-F-Ph, 4-Cl-Ph, 4
- Longhi, Kelvis,Moreira, Dayse N.,Marzari, Mara R.B.,Floss, Vagner M.,Bonacorso, Helio G.,Zanatta, Nilo,Martins, Marcos A.P.
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experimental part
p. 3193 - 3196
(2010/08/05)
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- Synthesis of pyrazoles through catalyst-free cycloaddition of diazo compounds to alkynes
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The synthesis of pyrazoles via 1,3-dipolar cycloaddition of diazo compounds to alkynes proceeds easily by heating. With α-diazocarbonyl substrates the reactions are conducted under solvent-free conditions affording the pyrazole products in high yields wit
- Vuluga, Daniela,Legros, Julien,Crousse, Benoit,Bonnet-Delpon, Daniele
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scheme or table
p. 156 - 159
(2010/04/22)
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- Efficient and simple synthesis of 3-aryl-1H-pyrazoles
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Efficient preparation of 3-aryl-1H-pyrazoles by reaction of 1-protected-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazoles with (het)aryl halides is described. The choice of THP protecting group is discussed.
- Gérard, Anne-Laure,Bouillon, Alexandre,Mahatsekake, Clément,Collot, Valérie,Rault, Sylvain
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p. 4665 - 4669
(2007/10/03)
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- A versatile method for suzuki cross-coupling reactions of nitrogen heterocycles
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(Chemical Equation Presented) A wide-ranging study of Suzuki reactions which use nitrogen-containing heterocycles is described (see scheme; dba = dibenzylideneacetone, Cy = cyclohexyl). This method is highly versatile (a single procedure was used for all substrates, including boronate esters and trifluoroborates), compatible with a variety of unprotected functionalities (e.g., NH2-and OH-substituted substrates), and efficient even with unactivated aryl chlorides.
- Kudo, Noriaki,Perseghini, Mauro,Fu, Gregory C.
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p. 1282 - 1284
(2007/10/03)
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- Microwave-assisted synthesis of pyrazoles by 1,3-dipolar cycloaddition of diazo compounds to acetylene derivatives
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Microwave-assisted preparation of a wide range of 5-ethoxycarbonylpyrazoles and 3-pyrazoles by 1,3-dipolar cycloaddition of diazo compound to acetylenes is described. All reactions were carried out using high throughput sequential technique.{A figure is p
- Zrinski, Irena,Juribasic, Marina,Eckert-Maksic, Mirjana
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p. 1961 - 1967
(2007/10/03)
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- The α-effect in reactions of sp-hybridized carbon atom: Michael-type reactions of 1-aryl-2-propyn-1-ones with primary amines
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Second-order rate constants (kN) have been measured for the Michael-type reaction of 1-(X-substituted phenyl)-2-propyn-1-ones (2a-f) with a series of primary amines in H2O at 25.0 ± 0.1 °C. A linear Bronsted-type plot with a small βnuc value (βnuc = 0.30) has been obtained for the reactions of 1-phenyl-2-propyn-1-one (2c) with non-α-nucleophile amines. Hydrazine is more reactive than other primary amines of similar basicity (e.g., glycylglycine and glycine ethyl ester) and results in a positive deviation from the linear Bronsted-type plot. The reactions of 2a-f with hydrazine exhibit a linear Hammett plot, while those with non-α-nucleophile amines give linear Yukawa-Tsuno plots, indicating that the electronic nature of the substituent X does not affect the reaction mechanism. The α-effect increases as the substituent X in the phenyl ring of 2a-f becomes a stronger electron-donating group. However, the magnitude of the α-effect for the reactions of 2a-f is small (e.g., kNhydrazine/kN glycylglycine = 4.6-13) regardless of the electronic nature of the substituent X. The small βnuc has been suggested to be responsible for the small α-effect. A solvent kinetic isotope effect (e.g., kNH2O/kND2O = 1.86) was observed for the reaction with hydrazine but absent for the reactions with non-α-nucleophile amines. The reactions with hydrazine and other primary amines have been suggested to proceed through a five-membered intramolecular H-bonding structure VI and a six-membered intermolecular H-bonding structure VII, respectively. The transition state modeled on VI can account for the substituent dependent α-effect and the difference in the solvent kinetic isotope effect exhibited by the reactions with hydrazine and other primary amines. It has been proposed that the βnuc value is more important than the hybridization type of the reaction site to determine the magnitude of the α-effect.
- Um, Ik-Hwan,Lee, Eun-Ju,Seok, Jin-Ah,Kim, Kyung-Hee
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p. 7530 - 7536
(2007/10/03)
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- A novel one-pot method for the preparation of pyrazoles by 1,3-dipolar cycloadditions of diazo compounds generated in situ
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A convenient one-pot procedure for the preparation of pyrazoles by 1,3-dipolar cycloaddition of diazo compounds generated in situ has been developed. Diazo compounds derived from aldehydes were reacted with terminal alkynes to furnish regioselectively 3,5-disubstituted pyrazoles. Furthermore, the reaction of N-vinylimidazole and diazo compounds derived from aldehydes gave exclusively 3-substituted pyrazoles in a one-pot process.
- Aggarwal, Varinder K.,De Vicente, Javier,Bonnert, Roger V.
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p. 5381 - 5383
(2007/10/03)
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- Selective C-arylation of free (NH)-heteroarenes via catalytic C-H bond functionalization
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A new system for palladium-catalyzed arylation of a broad spectrum of free (NH)-heteroarenes has been developed (indole, pyrrole, pyrazole, 2-phenylimidazole, imidazole, benzimidazole, and purine). Remarkable selectivity has been achieved in the presence of MgO base, providing single C-arylation products, while no N-arylation and no bis-arylation products have been detected. In the case of free imidazole, exclusive C-4 arylation may be switched to exclusive 2-arylation by the addition of CuI to the Pd/Ph3P/MgO system. When free aryl-(NH)-azoles are desired, direct arylation eliminates three steps in comparison to standard methods, including N-protection, stoichiometric metalation or halogenation, and N-deprotection. Copyright
- Sezen, Bengue,Sames, Dalibor
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p. 5274 - 5275
(2007/10/03)
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- Effective and highly stereoselective coupling with vinyldiazomethanes to form symmetrical trienes
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Diazo coupling reactions are capable of forming E,E,E-trienes from cinnamaldehydes in good yield. An efficient methodology is reported for the production of styryldiazomethanes that are subsequently used with catalysis for coupling and for cyclopropanatio
- Doyle, Michael P.,Yan, Ming
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p. 602 - 604
(2007/10/03)
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- Polymorphism vs. desmotropy: The cases of 3-phenyl- and 5-phenyl-1H-pyrazoles and 3-phenyl-1H-indazole
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Two desmotropes, 3-phenyl-1H-pyrazole (1a) and 5-phenyl-1H-pyrazole (1b) have been isolated and the conditions for their interconversion established. The X-ray structure of 1b has been determined (a = 10.862(1), b = 5.7620(5), c = 12.927(2) A, β = 111.435
- Garcia, Maria Angeles,Lopez, Concepcion,Claramunt, Rosa M.,Kenz, Ahmed,Pierrot, Marcel,Elguero, Jose
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p. 2763 - 2776
(2007/10/03)
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- Microwave assisted synthesis of 1-aryl-3-dimethylaminoprop-2-enones: A simple and rapid access to 3(5)-arylpyrazoles
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Condensation of aromatic acyl compounds with N,N-dimethylformamide diethyl acetal in a pressure tube under microwave heating gives 1-aryl-3-dimethylaminoprop-2-enones in almost quantitative yields. In the presence of hydrazine, these intermediates are transferred to the corresponding 3-arylpyrazoles.
- Pleier,Glas,Grosche,Sirsch,Thiel
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- Reactivity of bifunctional olefins with hydrazine hydrate - Part II
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The reaction of 1-aroyl-2-arylsulfonylethenes 1 with different ratios of hydrazine hydrate lead to hydrazones, dimerized products and 2-pyrazolines. The reactivity of pyrazolines has also been studied by dehydrogenation, pyrolysis, nitrosation and acylation.
- Bhaskar Reddy,Rajagopal Sarma,Somasekhar Reddy,Subba Reddy
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p. 901 - 903
(2007/10/03)
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- Novel C-Alkylation Reaction of Condensed Thiophenes with Enaminones, Enaminonitriles, Ethoxymethylenemalonitrile, Aryl Vinyl Ketones and ω-Nitrostyrenes
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The reaction of 1 with enaminones (3a-c) affords either the enaminones 4a-c or a mixture of 4a-c and the α,β-unsaturated ketones 9a-c depending on applied reaction conditions. Compounds 4a-c rearranged into 9a-c on long reflux in dioxane solution in prese
- Al-Etabi, Alya,Al-Awadi, Nouria,Al-Omran, Fatima,Abdel-Khalik, Mervat Mohammed,Elnagdi, Mohamed Hilmy
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p. 151 - 163
(2007/10/03)
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- Functionalised Pyrazoles through a Facile One-Pot Procedure from N-Tosyl-N-propargylhydrazine and Aryl Iodides or Vinyl Triflates
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Functionalised pyrazoles have been prepared in good overall yield through a facile one-pot procedure. The synthesis includes the palladium-catalysed coupling of the readily available N-tosyl-N-propargylhydrazine with aryl iodides or vinyl triflates, the palladium-catalysed annulation of the resulting N-tosyl-N-(1-aryl/vinyl-1-propyn3-yl)hydrazine and exposure of the reaction mixture arising from the annulation step to KOBut.
- Cacchi, Sandro,Fabrizi, Giancarlo,Carangio, Antonella
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p. 959 - 961
(2007/10/03)
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