53531-57-0Relevant articles and documents
Pyridine Skeleton Synthesis Using Acetonitrile as C4N1 Units and Solvent
Bai, Chaolumen,Guo, Huifang,Liu, Xin,Liu, Dan,Sun, Zhaorigetu,Bao, Agula,Baiyin, Menghe,Muschin, Tegshi,Bao, Yong-Sheng
, p. 12664 - 12675 (2021/09/18)
The first [3 + 2 + 1] methodology for pyridine skeleton synthesis via cascade carbopalladation/cyclization of acetonitrile, arylboronic acids, and aldehydes was developed. This reaction proceeds via six step tandem reaction sequences involving the carbopalladation reaction of acetonitrile, a nucleophilic addition, a condensation, an intramolecular Michael addition, cyclization, and aromatization. Delightfully, both palladium acetate and supported palladium nanoparticles catalyzed this reaction with similar catalytic performance. The characterization results of the fresh and used supported palladium nanoparticle catalysts indicated that the reaction might be performed via a Pd(0)/Pd(II) catalytic cycle that began with Pd(0). Furthermore, the products showed good fluorescence characteristics. The green homogeneous/heterogenous catalytic methodologies pave a new way for constructing the pyridine skeleton.
The photochemical alkylation and reduction of heteroarenes
McCallum,Pitre,Morin,Scaiano,Barriault
, p. 7412 - 7418 (2017/10/31)
The functionalization of heteroarenes has been integral to the structural diversification of medicinally active molecules such as quinolines, pyridines, and phenanthridines. Electron-deficient heteroarenes are electronically compatible to react with relatively nucleophilic free radicals such as hydroxyalkyl. However, the radical functionalization of such heteroarenes has been marked by the use of transition-metal catalyzed processes that require initiators and stoichiometric oxidants. Herein, we describe the photochemical alkylation of quinolines, pyridines and phenanthridines, where through direct excitation of the protonated heterocycle, alcohols and ethers, such as methanol and THF, can serve as alkylating agents. We also report the discovery of a photochemical reduction of these heteroarenes using only iPrOH and HCl. Mechanistic studies to elucidate the underlying mechanism of these transformations, and preliminary results on catalytic methylations are also reported.
Molecular Iodine-Mediated Chemoselective Synthesis of Multisubstituted Pyridines through Catabolism and Reconstruction Behavior of Natural Amino Acids
Xiang, Jia-Chen,Wang, Miao,Cheng, Yan,Wu, An-Xin
supporting information, p. 24 - 27 (2016/01/15)
A new process has been developed for the selective construction of 2,6-disubstituted, 2,4,6-trisubstituted, and 3,5-disubstituted pyridines based on the catabolism and reconstruction behaviors of amino acids. Molecular iodine was used as a tandem catalyst to trigger the decarboxylation-deamination of amino acids and to promote the subsequent formation of the pyridine products.
A modular synthesis of functionalized pyridines through lewis-acid-mediated and microwave-assisted cycloadditions between azapyrylium intermediates and alkynes
Linder, Igor,Gerhard, Markus,Schefzig, Luise,Andrae, Michal,Bentz, Christoph,Reissig, Hans-Ulrich,Zimmer, Reinhold
supporting information; experimental part, p. 6070 - 6077 (2011/12/02)
In this report we describe the synthesis of differentially functionalized pyridine derivatives 3 and the related 3-bromo-substituted pyridines 11. Dissociation of 6H-1,2-oxazine precursors (1a, 1b, 5, 6, or 12) in situ, mediated by boron trifluoride-diethyl ether, generates the azapyrylium intermediates A, which undergo hetero-Diels-Alder reactions with various mono- and disubstituted alkynes 2. In general, these pyridine syntheses proceeded with high efficiencies and were very flexible with respect to all positions in the pyridine cores. For the 3-phenyl-substituted pyridine derivatives 3a-3j and 11a-11f the best results were obtained by a new microwave-assisted protocol, which is clearly superior to the previously used conventional procedure at low temperature in dichloromethane. Furthermore, 3-(trifluoromethyl)- and 3-acryloyl-substituted 6H-1,2-oxazines reacted cleanly under microwave irradiation conditions to furnish the expected pyridine derivatives 3k and 3l in respectable yields. The 3-bromo-substituted pyridines 11 were further functionalized through palladium-catalyzed couplings such as Suzuki or Sonogashira reactions, which led smoothly to tri- or tetrasubstituted pyridine derivatives such as 19-21 and 23. Reductive debromination of 11e afforded the pyridine 17 in excellent yield, whereas oxidation of the pyridinyl thioether 3g with oxone led to the corresponding sulfoxide 24. Our method thus establishes a new and versatile approach to highly substituted pyridine derivatives. A simple method for the modular synthesis of substituted pyridines is disclosed. Microwave-assisted reactions between azapyrylium intermediates (generated in situ) and alkynes afforded the corresponding pyridine derivatives in good to excellent yields. The functional group tolerance in this process is very good and allows a variety of subsequent reactions.
Mn(III)-mediated formal [3+3]-annulation of vinyl azides and cyclopropanols: A divergent synthesis of azaheterocycles
Wang, Yi-Feng,Toh, Kah Kah,Ng, Eileen Pei Jian,Chiba, Shunsuke
supporting information; experimental part, p. 6411 - 6421 (2011/06/19)
Mn(III)-mediated formal [3+3]-annulation has been developed using readily available vinyl azides and cyclopropanols with a wide range of substituents. Vinyl azides were successfully applied as a three-atom unit including one nitrogen to prepare pyridines and σ-lactams by the reactions with monocyclic cyclopropanols as well as to construct 2-azabicyclo[3.3.1] and 2-azabicyclo[4.3.1] frameworks with bicyclic cyclopropanols, bicyclo[3.1.0]hexan-1-ols, and bicyclo[4.1.0]heptan-1-ols. These reactions were initiated by a radical addition of β-carbonyl radicals, generated by the one-electron oxidation of cyclopropanols with Mn(III), to vinyl azides to give iminyl radicals, which cyclized with the intramolecular carbonyl groups. In addition, application of the present methodology to a synthesis of the quaternary indole alkaloid, melinonine-E, was accomplished.
Synthesis and identification of a trimethylenemethane derivative π-extended with three pyridinyl radicals
Matsumoto, Kouzou,Lnokuchi, Dalsuke,Hirao, Yasukazu,Kurata, Hiroyukl,Sato, Kazunobu,Takul, Takeji,Kubo, Takashl
supporting information; experimental part, p. 836 - 839 (2010/04/06)
A trimethylenemethane (TMM) derivative 12., In which the parent TMM is π-extended by the symmetric Insertion of three pyridine rings Into the C-C bonds of TMM, has been synthesized by the alkali metal reduction of the Isolated corresponding dication. Although the frozen-glass X-band cw-ESR spectrum of 12. gave unresolved fine structures due to the small ZFS parameters, pulsed ESR two-dimensional electron spin transient nutation (2D-ESTN) spectroscopy unambiguously can afford to Identify diradical 1 2. as a triplet species.
Direct ortho-arylation of N-phenacylpyridinium bromide by palladium-catalyzed C-H-bond activation
Xu, Jimin,Cheng, Guolin,Su, Deyong,Liu, Yantao,Wang, Xinyan,Hu, Yuefei
supporting information; experimental part, p. 13105 - 13110 (2010/06/16)
A novel palladium catalyzed direct ortho-arylation of N-phenacylpyridinium bromide was developed. The amazing N-phenacyl group regioselectively activates the C-H bond of pyridine and automatically departs from the arylated products. A kinetic isotope effe
Mn(III)-mediated reactions of cyclopropanols with vinyl azides: Synthesis of pyridine and 2-azabicyclo[3.3.1]non-2-en-1-ol derivatives
Wang, Yi-Feng,Chiba, Shunsuke
supporting information; experimental part, p. 12570 - 12572 (2010/01/30)
(Chemical Equation Presented) A Mn(III)-mediated divergent synthesis of substituted pyridines and 2-azabicyclo[3.3.1]non-2-en-1-ol derivatives was exploited using readily available vinyl azides and cyclopropanols with a wide range of substituents. In short, the reactions of vinyl azides with monocyclic cyclopropanol provided pyridines in the presence of Mn(acac)3 (1.7 equiv), whereas those with bicyclic cyclopropanols led to the formation of 2-azabicyclo[3.3.1]non-2-en-1-ol derivatives using a catalytic amount of Mn(acac)3. These reactions may be initiated by a radical addition of β-keto radicals, generated by the one-electron oxidation of cyclopropanols, to vinyl azides to give iminyl radicals, which would cyclize with the intramolecular carbonyl groups. In addition, versatile transformations of 2-azabicyclo[3.3.1] non-2-en-1-ol to 2-azabicyclo[3.3.1]nonane or -non-2-nen frameworks were developed.
Unprecedented double C-C bond cleavage of a cyclopentadienyl ligand
Xi, Zhenfeng,Sato, Kimihiko,Gao, Ye,Lu, Jianming,Takahashi, Tamotsu
, p. 9568 - 9569 (2007/10/03)
Double C-C bond cleavage of a cyclopentadienyl ligand proceeded to titanacyclopentadienes when 2 equiv of nitriles were added and the resulting two-carbon unit and three-carbon unit were converted into a benzene derivative and a pyridine derivative, respectively, in one-pot. Copyright
Transformations of mono- and bisphenylhydrazones of aliphatic-aromatic 1,5-diketones under the conditions of the fischer reaction
Moskovkina
, p. 1190 - 1199 (2007/10/03)
The mono- and bisphenylhydrazones of 3-R-1,5-diphenylpentane-1,5-diones were obtained, and their transformations in the Fischer indole synthesis under various conditions were studied. It was shown that 4-R-2,6-diphenylpyridines, 2-phenylindole, and 5-R-1,-3-diphenyl-Δ2-pyrazolines are formed as the main products in addition to the 3-R-1-phenyl-3-(2-phenyl-3-indolyl)propan-1-ones or their phenylhydrazones produced as a result of indolization. The ways of formation of these compounds are discussed. Some transformations of the obtained ketones were studied.
