- Synthesis and metallation of 2-(pyridyl)benzoic acids and ethyl 2-(pyridyl)benzoates: A new route to azafluorenones
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The ring deprotonation of 2-(2- and 4-pyridyl)benzoic acids using lithium dialkylamides in THF at rt, and the in situ cyclization afforded 4- and 2-azafluorenones, respectively. 1-Azafluorenone was obtained from ethyl 2-(3-pyridyl)benzoate using a similar protocol.
- Rebstock, Anne-Sophie,Mongin, Florence,Trécourt, Fran?ois,Quéguiner, Guy
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- Cobalt-catalyzed cross-coupling of nitrogen-containing heterocyclic phosphonium salts with arylmagnesium reagents
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Cobalt-catalyzed cross-couplings of nitrogen-containing heterocyclic phosphonium salts with arylmagnesium halides proceeded efficiently with the aid of cobalt(II) catalyst and copper(I) salt in tetrahydrofuran at ambient temperature, producing the desired
- Cui, Yan-Ying,Na, Jin-He,Guo, Meng-Meng,Huang, Jie-Ying,Chu, Xue-Qiang,Rao, Weidong,Shen, Zhi-Liang
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supporting information
(2022/02/16)
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- Phosphonium Salts as Pseudohalides: Regioselective Nickel-Catalyzed Cross-Coupling of Complex Pyridines and Diazines
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Heterobiaryls are important pharmacophores that are challenging to prepare by traditional cross-coupling methods. An alternative approach is presented where pyridines and diazines are converted into heteroaryl phosphonium salts and coupled with aryl boronic acids. Nickel catalysts are unique for selective heteroaryl transfer, and the reaction has a broad substrate scope that includes complex pharmaceuticals. Phosphonium ions also display orthogonal reactivity in cross-couplings compared to halides, enabling chemoselective palladium- and nickel-catalyzed coupling sequences.
- Zhang, Xuan,McNally, Andrew
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p. 9833 - 9836
(2017/08/08)
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- The use of organolithium reagents for the synthesis of 4-aryl-2-phenylpyridines and their corresponding iridium(III) complexes
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A versatile palladium-free route for the synthesis of 4-aryl-substituted phenylpyridines (ppy), starting from tert-butyl 4-oxopiperidine-1-carboxylate, is reported. Reaction with an aryllithium, followed by trifluoroacetic acid dehydration/deprotection and oxidation with 2-iodoylbenzoic acid and finally phenylation, gave 4 ligands (L1-4H): 2,4-diphenylpyridine, 4-(4-methoxyphenyl)-2-phenylpyridine, 2-phenyl-4-(o-tolyl)pyridine and 4-mesityl-2-phenylpyridine. These ligands were coordinated to iridium to give the corresponding Ir(L)2(A) complexes (Ir1-7), where A = ancillary ligand acetylacetate or 2-picolinate. This was used to demonstrate that, through a combination of ancillary ligand choice and torsional twisting between the 4-aryl substituents of the ppy ligands, it is possible to tune the phosphorescent emission of the complexes in the range 502-560 nm.
- Davidson, Ross,Hsu, Yu-Ting,Batchelor, Thomas,Yufit, Dmitry,Beeby, Andrew
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p. 11496 - 11507
(2016/07/26)
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- Palladium-catalyzed decarboxylative cross-coupling of 3-pyridyl and 4-pyridyl carboxylates with aryl bromides
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Decarboxylative cross-coupling of 3-pyridyl and 4-pyridyl carboxylates with aryl bromides is reported. Using a bimetallic system of Cu2O and Pd(PPh3)4, the scope of the reaction is demonstrated by the synthesis of 27 pyridine-containing biaryls in moderate to good yields.
- Chennamaneni, Lohitha Rao,William, Anthony D.,Johannes, Charles W.
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p. 1293 - 1296
(2015/03/04)
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- Palladium dichloride adduct of N,N-bis-(diphenylphosphanylmethyl)-2- aminopyridine: Synthesis, structure and catalytic performance in the decarboxylative cross-coupling of 4-picolinic acid with aryl bromide
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Reaction of PdCl2 with N,N-bis-(diphenylphosphanylmethyl)-2- aminopyridine (bdppmapy) afforded a mononuclear complex [(bdppmapy)PdCl 2] (1). Compound 1 was characterized by elemental analysis, IR, 1H, 13C and 31P NMR, electrospray ion mass spectra (ESI-MS) and X-ray single crystal crystallography. The Pd(ii) center in 1 is chelated by bdppmapy, showing a cis-square planar geometry. With the assistance of additive Cu2O, complex 1 exhibited good catalytic activity toward the decarboxylative cross-coupling reactions between 4-picolinic acid and aryl bromides. In the presence of only 2 mol% catalyst, a family of 4-aryl-pyridines could be isolated in up to 83% yield.
- He, Run-Tian,Wang, Jian-Feng,Wang, Hui-Fang,Ren, Zhi-Gang,Lang, Jian-Ping
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p. 9786 - 9794
(2014/06/23)
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- Clean and fast cross-coupling of aryl halides in one-pot
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Unsymmetrically coupled biaryls are synthesized in high yield starting from different aryl bromides and bis(pinacolato)diboron by carrying out the Miyaura borylation reaction followed by the Suzuki-Miyaura reaction in the same reaction pot over 1-2 mol % SiliaCat DPP-Pd. The SiliaCat DPP-Pd catalyst is air-stable and the method does not require the use of inert conditions. The use of non-toxic isopropanol or 2-butanol as reaction solvent further adds to the environmental benefits of this new green synthetic methodology.
- Pandarus, Valerica,Gingras, Genevieve,Beland, Francois,Ciriminna, Rosaria,Pagliaro, Mario
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p. 897 - 901
(2014/05/20)
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- Metal-free arylation of benzene and pyridine promoted by amino-linked nitrogen heterocyclic carbenes
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An amino-linked nitrogen heterocyclic carbene (amino-NHC), 1-tBu, has been shown to mediate carbon-carbon coupling through the direct C-H functionalization of benzene and pyridine in the absence of a metal catalyst. Using EPR, the first spectroscopic evidence corroborating the single electron transfer mechanism for the metal-free carbon-carbon coupling manifold, as reported by others, is introduced.
- Chen, Wen-Ching,Hsu, Yu-Chen,Shih, Wei-Chun,Lee, Ching-Yu,Chuang, Wen-Han,Tsai, Yi-Fang,Chen, Peter Ping-Yu,Ong, Tiow-Gan
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supporting information; experimental part
p. 6702 - 6704
(2012/07/14)
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- Gold(I)-catalyzed direct C-H arylation of pyrazine and pyridine with aryl bromides
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An efficient procedure for the direct C-H arylation of electron-poor aromatics such as pyrazine and pyridine with aryl bomides is described. In the presence of catalytic amount of Cy3PAuCl and with the use of t-BuOK as base, pyrazine undergoes the direct C-H arylation with aryl bromides at 100 °C, and the yields of the arylated products depend on the nature of aryl bromides. In the cases of electron-rich aryl bromides used, the arylated pyrazines can be obtained in good to high yields. For electron-poor aryl bromides, the addition of AgBF4 is the crucial point to accelerate the coupling reaction to give the arylated products in moderate yields. Pyridine also reacts with electron-rich aryl bromides catalyzed by Cy3PAuCl to give a mixture of arylated regioisomers in moderate yield. However, in order to realize the direct C-H arylation of pyridine with electron-poor aryl bromides, the addition of silver salt as additive and a milder reaction temperature (60 °C) are required.
- Li, Ming,Hua, Ruimao
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supporting information; experimental part
p. 1478 - 1481
(2009/06/08)
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- Design and synthesis of 6-fluoro-2-naphthyl derivatives as novel CCR3 antagonists with reduced CYP2D6 inhibition
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In our previous study on discovering novel types of CCR3 antagonists, we found a fluoronaphthalene derivative (1) that exhibited potent CCR3 inhibitory activity with an IC50 value of 20 nM. However, compound 1 also inhibited human cytochrome P450 2D6 (CYP2D6) with an IC50 value of 400 nM. In order to reduce its CYP2D6 inhibitory activity, we performed further systematic structural modifications on 1. In particular, we focused on reducing the number of lipophilic moieties in the biphenyl part of 1, using C log D7.4 values as the reference index of lipophilicity. This research led to the identification of N-{(3-exo)-8-[(6-fluoro-2-naphthyl)methyl]-8-azabicyclo[3.2.1]oct-3-yl}-3-(piperidin-1-ylcarbonyl)isonicotinamide 1-oxide (30) which showed comparable CCR3 inhibitory activity (IC50 = 23 nM) with much reduced CYP2D6 inhibitory activity (IC50 = 29,000 nM) compared with 1.
- Sato, Ippei,Morihira, Koichiro,Inami, Hiroshi,Kubota, Hirokazu,Morokata, Tatsuaki,Suzuki, Keiko,Iura, Yosuke,Nitta, Aiko,Imaoka, Takayuki,Takahashi, Toshiya,Takeuchi, Makoto,Ohta, Mitsuaki,Tsukamoto, Shin-ichi
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p. 8607 - 8618
(2008/12/23)
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- Vesicular monoamine transporter substrate/inhibitor activity of MPTP/MPP+ derivatives: A structure-activity study
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The active metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), N-methyl-4-phenylpyridinium (MPP+), selectively destroys the dopaminergic neurons and induces the symptoms of Parkinson's disease. Inhibition of mitochondrial complex
- Wimalasena, D. Shyamali,Perera, Rohan P.,Heyen, Bruce J.,Balasooriya, Inoka S.,Wimalasena, Kandatege
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p. 760 - 768
(2008/09/19)
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- Microwave-assisted Suzuki coupling reactions with an encapsulated palladium catalyst for batch and continuous-flow transformations
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This article describes the design, optimisation and development of a Suzuki cross-coupling protocol mediated by an efficient palladium-en-capsulated catalyst (Pd EnCat) under microwave irradiation. The methodology has been used in both batch mode for classical library preparation and in continuous-flow applications furnishing multigram quantities of material. Described is a method that uses direct focused microwave heating whilst applying an external cooling source. This enables a lower than normal bulk temperature to be maintained throughout the reaction period leading to significant improvements in the overall yield and purity of the reaction products. Additional aspects of this novel heating protocol are discussed in relation to the prolonged lifetime and enhanced reactivity of the immobilised catalyst system.
- Baxendale, Ian R.,Griffiths-Jones, Charlotte M.,Ley, Steven V.,Tranmer, Geoffrey K.
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p. 4407 - 4416
(2008/02/07)
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- Efficient coupling of heteroaryl halides with arylboronic acids in the presence of a palladium-tetraphosphine catalyst
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Cis, cis, cis-1,2,3,4-tetrakis(diphenylphosphinomethyl) cyclopentane: ·1/2[PdCl(C3H5)]2 system catalyses the Suzuki cross-coupling of heteroaryl halides with a range of arylboronic acids with very high ratio substrate/catalyst in good yields. Substrates such as pyridines, quinolines, thiophenes, an indole, pyrimidines or a furane have been used successfully.
- Feuerstein, Marie,Doucet, Henri,Santelli, Maurice
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p. 327 - 336
(2007/10/03)
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- In vivo intracerebral microdialysis studies in rats of MPP+ analogues and related charged species
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The in vivo dopaminergic neurotoxic properties of 45 MPTP and MPP+ analogues and related compounds were examined by an intrastriatal microdialysis assay in conscious rats. MPP+-like toxicity, as evidenced by the irreversible effects
- Rollema,Johnson,Booth,Caldera,Lampen,Youngster,Trevor,Naiman,Castagnoli Jr.
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p. 2221 - 2230
(2007/10/02)
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- THE PYRIDYL CATION AS A REACTIVE INTERMEDIATE IN THE PHOTOREACTION OF IODOPYRIDINES WITH BENZENES
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The electrophilic behavior of the reactive entity in the photosubstitution of benzenes with 2-iodopyridine was found to be ascribable to the intermediary 2-pyridyl cation, rather than the electrophilic 2-pyridyl radical.
- Ohkura, Kazue,Seki, Koh-ichi,Terashima, Masanao,Kanaoka, Yuichi
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p. 3433 - 3436
(2007/10/02)
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- Synthetic Applications of N-N Linked Heterocycles. Part 7. The Preparation of 4-Alkyl- and 4-Aryl-pyridines by Regiospecific Attack of Grignard Reagents γ to Quaternary Nitrogen in N-(2,6-Dimethyl-4-oxopyridin-1-yl)pyridinium Salts
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N-(2,6-Dimethyl-4-oxopyridin-1-yl)pyridinium salts (4), new reagents for the regiospecific synthesis of 4-substituted pyridines, give moderate to high yields of 4-alkyl- and 4-aryl-pyridines (8) - (10) on reaction with Grignard reagents.The scope and limitations on the reaction, which proceeds via 1,4-dihydro-intermediates (5) - (7), are explored.No 2-substituted pyridines were detected.Some reactions with organolithium compounds are also described.
- Katritzky, Alan R.,Beltrami, Hector,Sammes, Michael P.
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p. 2480 - 2484
(2007/10/02)
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