4373-68-6Relevant articles and documents
Quantifying Through-Space Substituent Effects
Adam, Catherine,Burns, Rebecca J.,Cockroft, Scott L.,Mati, Ioulia K.,Muchowska, Kamila B.
supporting information, p. 16717 - 16724 (2020/07/24)
The description of substituents as electron donating or withdrawing leads to a perceived dominance of through-bond influences. The situation is compounded by the challenge of separating through-bond and through-space contributions. Here, we probe the experimental significance of through-space substituent effects in molecular interactions and reaction kinetics. Conformational equilibrium constants were transposed onto the Hammett substituent constant scale revealing dominant through-space substituent effects that cannot be described in classic terms. For example, NO2 groups positioned over a biaryl bond exhibited similar influences as resonant electron donors. Meanwhile, the electro-enhancing influence of OMe/OH groups could be switched off or inverted by conformational twisting. 267 conformational equilibrium constants measured across eleven solvents were found to be better predictors of reaction kinetics than calculated electrostatic potentials, suggesting utility in other contexts and for benchmarking theoretical solvation models.
Photoarylation of Pyridines Using Aryldiazonium Salts and Visible Light: An EDA Approach
Bartolomeu, Aloisio De A.,Brocksom, Timothy J.,De Oliveira, Kleber T.,No?l, Timothy,Silva, Rodrigo C.
, (2019/08/26)
A metal-free methodology for the photoarylation of pyridines, in water, is described giving 2 and 4-arylated-pyridines in yields up to 96percent. The scope of the aryldiazonium salts is presented showing important results depending on the nature and position of the substituent group in the diazonium salt, that is, electron-donating or electron-withdrawing in the ortho, meta, or para positions. Further heteroaromatics were also successfully photoarylated. Mechanistic studies and comparison between our methodology and similar metal-catalyzed procedures are presented, suggesting the occurrence of a visible-light EDA complex which generates the aryl radical with no need for an additional photocatalyst.
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
He, Run-Tian,Wang, Jian-Feng,Wang, Hui-Fang,Ren, Zhi-Gang,Lang, Jian-Ping
, p. 9786 - 9794 (2014/06/23)
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.
Metal-free arylation of benzene and pyridine promoted by amino-linked nitrogen heterocyclic carbenes
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
supporting information; experimental part, p. 6702 - 6704 (2012/07/14)
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.
Pyridino-directed lithiation of anisylpyridines: New access to functional pyridylphenols
Parmentier, Micha?l,Gros, Philippe,Fort, Yves
, p. 3261 - 3269 (2007/10/03)
The lithiation of nine anisylpyridines has been studied. While usual reagents did not react or gave addition products on pyridine ring, the BuLi-LiDMAE (LiDMAE=Me2N(CH2)2OLi) superbase induced exclusive pyridino directed metallation. The usefulness of this new reaction allowed the efficient preparation of a range of alpha functional pyridylphenols. A successful subsequent cyclisation of an appropriate isomer into corresponding benzofuropyridine was also performed.
Synthesis of functionalized 4-phenyl-pyridines via electrochemically prepared organozinc reagents
Gall, Erwan Le,Gosmini, Corinne,Nédélec, Jean-Yves,Périchon, Jacques
, p. 1923 - 1927 (2007/10/03)
The efficient and convenient synthesis of various functionalized 4-phenyl-pyridines 2 is described. The key step of the procedure is the electrochemical formation of aromatic organozinc reagents 1 and their coupling with pyridinium salts. Intermediate 1,4
THE PYRIDYL CATION AS A REACTIVE INTERMEDIATE IN THE PHOTOREACTION OF IODOPYRIDINES WITH BENZENES
Ohkura, Kazue,Seki, Koh-ichi,Terashima, Masanao,Kanaoka, Yuichi
, p. 3433 - 3436 (2007/10/02)
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.
Studies on Tertiary Amine Oxides. LXXVII. The Pseudo-Gomberg Reaction of 4- and 2-Aminopyridine 1-Oxides
Saeki, Seitaro,Kondo, Sachiko,Hayashi, Takaaki,Hamana, Masatomo
, p. 1780 - 1789 (2007/10/02)
The 1-oxido-4-pyridyl radical generated by the reaction of 4-aminopyridine 1-oxide with amyl nitrite reacted smoothly with aromatic hydrocarbons, including five-membered heterocycles, i.e. thiophene, fyran and pyrrole, to give the arylated products when acetic acid was used as the solvent.The relative rates of reaction with the 1-oxido-4-pyridyl radical indicated that this radical is electrophilic, and this finding was supported by a comparison of molecular orbital energy levels. 2-Aminopyridine 1-oxide also undergoes a similar reaction.Keywords - pyridine N-oxide; Gomberg reaction; phenylpyridine; thienylpyridine; furylpyridine; 1-methanesulfonyl-pyrrolylpyridine; 1-oxido-4-pyridyl radical; molecular orbital; highperformance liquid chromatography
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
Katritzky, Alan R.,Beltrami, Hector,Sammes, Michael P.
, p. 2480 - 2484 (2007/10/02)
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.
