1003-67-4Relevant articles and documents
Visible-Light-Induced ortho-Selective Migration on Pyridyl Ring: Trifluoromethylative Pyridylation of Unactivated Alkenes
Jeon, Jinwon,He, Yu-Tao,Shin, Sanghoon,Hong, Sungwoo
, p. 281 - 285 (2020)
The photocatalyzed ortho-selective migration on a pyridyl ring has been achieved for the site-selective trifluoromethylative pyridylation of unactivated alkenes. The overall process is initiated by the selective addition of a CF3 radical to the alkene to provide a nucleophilic alkyl radical intermediate, which enables an intramolecular endo addition exclusively to the ortho-position of the pyridinium salt. Both secondary and tertiary alkyl radicals are well-suited for addition to the C2-position of pyridinium salts to ultimately provide synthetically valuable C2-fluoroalkyl functionalized pyridines. Moreover, the method was successfully applied to the reaction with P-centered radicals. The utility of this transformation was further demonstrated by the late-stage functionalization of complex bioactive molecules.
Grafting of a rhenium-oxo complex on Schiff base functionalized graphene oxide: An efficient catalyst for the oxidation of amines
Khatri, Praveen K.,Choudhary, Shivani,Singh, Raghuvir,Jain, Suman L.,Khatri, Om P.
, p. 8054 - 8061 (2014)
A rhenium-oxo complex such as methyltrioxorhenium (MTO) has been homogeneously immobilized on a Schiff base modified graphene oxide (GrO) support via covalent bonding. The loading of MTO on GrO nanosheets was monitored by FTIR, TG-DTA, and elemental analyses. The developed heterogeneous catalyst is found to be efficient for the oxidation of various amines to the corresponding N-oxides using hydrogen peroxide as an oxidant in high to excellent yields. At the end of the reaction, the catalyst is readily recovered by filtration and reused for subsequent runs. After the third run, the catalyst showed a marginal decrease in catalytic activity owing to the leaching of the MTO complex from the support. This journal is the Partner Organisations 2014.
A simple and efficient method for the preparation of pyridine-N-oxides II
Coperet, Christophe,Adolfsson, Hans,Chiang, Jay P.,Yudin, Andrei K.,Sharpless, K. Barry
, p. 761 - 764 (1998)
Oxidation of pyridines with bis(trimethylsilyl)peroxide in the presence of catalytic amounts of inorganic rhenium derivatives gives high yields of their analytically pure N-oxides by simple work-ups, typically a filtration or a Kugelrohr distillation.
Strategic Approach on N-Oxides in Gold Catalysis – A Case Study
Schie?l, Jasmin,Stein, Philipp M.,Stirn, Judith,Emler, Kirsten,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
, p. 725 - 738 (2019)
An extensive kinetic study of selected key reactions of (oxidative) gold catalysis concentrates on the decrease of the catalytic activity due to inhibition of the gold(I) catalyst caused by pyridine derivatives that are obtained as by-products if N-oxides are applied as oxygen donors. The choice of the examined pyridine derivatives and their corresponding N-oxides has been made regardless of their commercial availability; particular attention has been paid to the practical benefit which up to now has been neglected in most of the reaction screenings. The test reactions were monitored by GC and 1H NMR spectroscopy. The received reaction constants provide information concerning a correlation between the electronic structure of the heterocycle and the catalytic activity. Based on the collected kinetic data, it was possible to develop a basic set of three N-oxides which have to be taken into account in further oxidative gold(I)-catalyzed reactions. (Figure presented.).
Rational design, synthesis, and characterization of deep blue phosphorescent Ir(III) complexes containing (4′-Substituted-2′- pyridyl)-1,2,4-triazole ancillary ligands
Park, Hea Jung,Kim, Ji Na,Yoo, Hyun-Ji,Wee, Kyung-Ryang,Kang, Sang Ook,Cho, Dae Won,Yoon, Ung Chan
, p. 8054 - 8064 (2013)
On the basis of the results of frontier orbital considerations, 4-substituted-2′-pyridyltriazoles were designed to serve as ancillary ligands in 2-phenylpyridine main ligand containing heteroleptic iridium(III) complexes that display deep blue phosphorescence emission. The iridium(III) complexes, Ir1-Ir7, prepared using the new ancillary ligands, were found to display structured, highly quantum efficient (Φp = 0.20-0.42) phosphorescence with emission maxima in the blue to deep blue 448-456 nm at room temperature. In accord with predictions based on frontier orbital considerations, the complexes were observed to have emission properties that are dependent on the electronic nature of substituents at the C-4 position of the pyridine moiety of the ancillary ligand. Importantly, placement of an electron-donating methyl group at C-4′ of the pyridine ring of the 5-(pyridine-2′-yl)-3-trifluoromethyl-1,2,4-triazole ancillary ligand leads to an iridium(III) complex that displays a deep blue phosphorescence emission maximum at 448 nm in both the liquid and film states at room temperature. Finally, an OLED device, constructed using an Ir-complex containing the optimized ancillary ligand as the dopant, was found to emit deep blue color with a CIE of 0.15, 0.18, which is close to the perfect goal of 0.15, 0.15.
Synthese regioselective par voie organometallique de pyridines, 4-picolines et 3,5-lutidines substituees en 2 par un groupe insature et/ou fonctionnel
Al-Arnaout, A.,Courtois, G.,Miginiac, L.
, p. 139 - 154 (1987)
A regioselective one-pot synthesis of 2-substituted pyridine derivatives from N-alkoxycarboxylpyridinium salts and α-unsaturated organozinc compounds is described.Similarly, functional alkynyl organomagnesium compounds lead to 2-alkynyl-ω-functional pyridines, from which (E)-2-alkenyl or 2-alkyl-ω-functional pyridines can be obtained by partial or complete reduction.
Reaction of Pyridine-N-Oxides with Tertiary sp2-N-Nucleophiles: An Efficient Synthesis of Precursors for N-(Pyrid-2-yl)-Substituted N-Heterocyclic Carbenes
Bugaenko, Dmitry I.,Karchava, Alexander V.,Yurovskaya, Marina A.
, p. 5777 - 5782 (2020)
N-(Pyrid-2-yl)-substituted azolium and pyridinium salts, precursors for hybrid NHC-containing ligands, were obtained with excellent regioselectivity, employing a deoxygenative CH-functionalization of pyridine-N-oxides with substituted imidazoles, thiazoles, and pyridine. Unlike the traditional SNAr-based methods, this approach provides high yields for substrates bearing substituents of different electronic nature. The utility of azolium and pyridinium salts thus prepared was also highlighted by the synthesis of pyridyl-substituted imidazolyl-2-thione, benzodiazepine as well as 2-aminopyridines.
Ruthenium catalyzed oxidation of tertiary nitrogen compounds with molecular oxygen: An easy access to N-oxides under mild conditions
Jain, Suman L.,Sain, Bir
, p. 1040 - 1041 (2002)
A variety of tertiary nitrogen compounds have been efficiently oxidized to their corresponding N-oxides in excellent yields with molecular oxygen as a sole oxidant and ruthenium trichloride as catalyst.
Bromamine-T/RuCl3 as an efficient system for the oxidation of tertiary amines to N-oxides
Sharma, Vishal B.,Jain, Suman L.,Sain, Bir
, p. 4281 - 4283 (2004)
A variety of tertiary amines were efficiently and selectively oxidized to the corresponding N-oxides by bromamine-T using ruthenium trichloride as catalyst in alkaline (pH8.4) acetonitrile/water (1:1) at 80°C.
Preparation, characterization, and aquation kinetics of pyridine N-oxide complexes of chromium(III)
Kotowski, Mirjana,Marcec, Radovan,Butkovic, Vjera,Bakac, Andreja,Orhanovic, Matko
, p. 2894 - 2899 (2006)
A series of (H2O)5Cr(X-pyO)3+ ions (pyO = pyridine N-oxide, X = H, 3-CH3, 4-CH3, 4-OCH3, 4-NO2) were prepared by the reduction of the corresponding pyridine N-oxide adducts of diperoxochromium(VI) species with acidic ferrous perchlorate. The (H2O)5Cr(X-pyO)3+ complexes undergo aquation to yield Cr(H2O)63+ and X-pyO according to the rate law kobs = ko + k -1[H+]-1. The values of the rate constants extrapolated to 298 K at 1.0 M ionic strength are: k0 = 2.80 × 10-6 s-1, k-1 = 1.86 × 10-8 M s-1 (X = 4-NO2); 7.80 × 10-8, 6.27 × 10-10 (H); 4.80 × 10-8, 3.20 × 10 -10 (3-CH3); 3.05 × 10-8, 1.60 × 10-10 (4-CH3); and 2.37 × 10-9, 4.76 × 10-11 (4-OCH3). The reaction of the 4-OCH 3 complex exhibits two additional terms in the rate law, k 1[H+] + k-2[H+]-2. The binding of 4-OCH3-pyO to chromium is suggested to take place through the methoxy group. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
