1122-61-8Relevant articles and documents
C-Nitration of pyridine by the kyodai-nitration modified by the Bakke procedure. A simple route to 3-nitropyridine and mechanistic aspect of its formation
Suzuki, Hitomi,Iwaya, Masao,Mori, Tadashi
, p. 5647 - 5650 (1997)
N-Nitropyridinium nitrate was generated in situ from pyridine, nitrogen dioxide and ozone in an inert organic solvent and subsequently treated with aqueous sodium hydrogen sulfite to afford 3-nitropyridine in good yield, together with sodium pyridine-4-sulfonate as a water-soluble by-product.
2-, 3- and 4-[18F]fluoropyridine by no-carrier-added nucleophilic aromatic substitution with K[18F]F-K222 - A comparative study
Karramkam,Hinnen,Vaufrey,Dolle
, p. 979 - 992 (2003)
Compared to homoaromatic and aliphatic nucleophilic radiofluorinations, only few references can be found in the literature describing nucleophilic substitutions with [18F]fluoride ion of heteroaromatic compounds such as pyridines and only reactions involving fluorination processes at the ortho-position (2-position) have been more intensively studied. In the present paper, the scope of the nucleophilic aromatic fluorinations at the meta- and paraposition of the pyridine ring with no-carrier-added [18F] fluoride ion as its activated K [18F]F-K222 complex has been evaluated and compared to the nucleophilic aromatic fluorinations at the ortho-position in this pyridine series. The syntheses of 3- and 4- [ 18F]fluoropyridines were chosen as model reactions and compared to the radiosynthesis of 2-[18F]fluoropyridine. The parameters studied include the influence of the position of the leaving group at the pyridine ring, as well as the quantity of the precursor used, the type of activation (conventional heating, microwave irradiation), the solvent, the temperature and the reaction time. Using the corresponding nitro precursor, high yields were obtained at the 2-position (94% yield) using microwaves (100 W) for 2 min in DMSO. Good yields (up to 72%) were observed at the 4-position using the same conditions while practically no reaction was observed at the 3-position. About 60% yield was also obtained at both the 2- and 4-position using the corresponding nitro precursor at 145°C for 10 min in DMSO. Copyright
A two-step continuous flow synthesis of 4-nitropyridine
Wan, Zhidong,Fang, Zheng,Yang, Zhao,Liu, Chengkou,Gu, Jiajia,Guo, Kai
, p. 209 - 212 (2015)
4-Nitropyridine, a key intermediate in medicinal products, was successfully prepared from pyridine N-oxide in a two-step -approach. Pyridine N-oxide was nitrated with HNO3 and H2SO4 to give 4-nitropyridine N-oxide, followed by reaction with PCl3 to give the final product. The continuous flow methodology was used to minimise accumulation of the highly energetic and potentially explosive nitration product to enable the safe scale-up of 4-nitropyridine with no 2-nitropyridine by-product. By employing continuous extraction in the nitration step and applying the optimised conditions, a throughput of 0.716 kg 4-nitropyridine product per day from pyridine N-oxide with 83% yield and high selectivity in a continuous flow system was achieved.
A computational approach to tuning the photochemistry of platinum(IV) anticancer agents
Tai, Hui-Chung,Zhao, Yao,Farrer, Nicola J.,Anastasi, Anna E.,Clarkson, Guy,Sadler, Peter J.,Deeth, Robert J.
, p. 10630 - 10642,13 (2012)
Diazido PtIV complexes are inert stable prodrugs that can be photoactivated to produce PtII species with promising anticancer activity. Our studies of the photochemistry of PtIV complexes, [Pt(X)2(Y)2(Z)2]0/-1 (X=N-ligands (NH3, pyridine, etc.)/S(CH3)2/H-, Y=(pseudo)halogen (N3-, I-), Z=OR-, R=H, Ac) by time-dependent density functional theory (TDDFT) show close agreement with spectroscopic data. Broad exploration of cis/trans geometries, trans influences, the nature of the OR- and (pseudo)halogen ligands, electron-withdrawing/donating/delocalising substituents on the N-ligands, and intramolecular H bonds shows that: 1) the design of platinum(IV) complexes with intense bands shifted towards longer wavelengths (from 289 to ～330 nm) can be achieved by introducing intramolecular H bonds involving the OH ligands and 2-hydroxyquinoline or by iodido ligands; 2) mesomeric electron-withdrawing substituents on pyridine result in low-energy absorption with significant intensity in the visible region; and 3) the distinct makeup of the molecular orbitals involved in the electronic transitions for cis/trans-{Pt(N 3)2} isomers results in different photoproducts. In general, the comparison of the optimised geometries shows that PtIV complexes with longer Pt-L bonds are more likely to undergo photoreduction with longer-wavelength light. The novel complex trans,trans,trans-[Pt(N 3)2(OH)2(NH3)(4-nitropyridine)] with predicted absorption in the visible region has been synthesised. The experimental UV/Vis spectrum in aqueous solution correlates well with the intense band in the computed spectrum, whereas the overlay in the low-energy region can be improved by a solvent model. This combined computational and experimental study shows that TDDFT can be used to tune the coordination environment for optimising photoactive PtIV compounds as anticancer agents. Computer-aided design: Platinum(IV) complexes are inert stable prodrugs that can be photoactivated to produce species with promising anticancer activity. Here a combined computational and experimental study was carried out to show that TDDFT can aid the design of the coordination environment of Pt IV complexes to allow optimisation of the photoactivity of these PtIV anticancer agents (see figure). Copyright
Kinetics and mechanistic study on deoxygenation of pyridine oxide catalyzed by {MeReVO(pdt)} 2 dimer
Ibdah, Abdellatif,Alduwikat, Salwa
supporting information, p. 9 - 20 (2017/05/19)
The oxorhenium(V) dimer {MeReO(pdt)}2 (where pdt?=?1,2-propanedithiolate) catalyze the oxygen atom transfer (OAT) reaction from the pyridine oxide to triphenylarsine (Ph3As). The rate law is given by ν?=?k[Re-dimer][PyNO] and zero order dependence on Ph3As. The value of k at 25?°C in CHCl3 is 139?±?3?L?mol?1?s?1. The activation parameters are ΔH??=?12.2?±?1.0?kcal?mol?1 and ΔS??=??7.9?±?3.24?cal?K?1?mol?1. According to the proposed mechanism, the rate determining step is the oxidation of ReVO to ReVIIO2 and the pyridine release. The triphenylarsine enters the catalytic cycle after the rate determining step. The reaction constant ρ?=??1.4 obtained from Hammett correlation with σ for different substituted pyridine N-oxide. The computational study indicates that the oxidation of ReV to ReVII and release of the pyridine step is insensitive to the nature of the substituent on the pyridine with the average estimated activation barrier ≈11.5?kcal/mol from six different substituted pyridine oxide. It is proposed that electron donor substituent enrich the equilibrium of the first step of the proposed mechanism which is the coordination of the pyridine oxide with one rhenium atom to form I1 (Scheme 2). The electron donor substituent on the pyridine increase the concentration of I1 which will increase the rate of the reaction as the ν?=?k2[I1].
Synthetic method of 4-pyridylaldehyde
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Paragraph 0032; 0033; 0038; 0043, (2017/11/18)
The invention relates to the field of organic chemistry, in particular to a synthetic method of 4-pyridylaldehyde. The synthetic method comprises the following steps: 1, taking 4-methyl pyridine as a raw material and obtaining 4-pyridine nitrogen oxide through oxidation reaction under an acidic condition; 2, synthesizing the 4-pyridine nitrogen oxide into acetic acid-4-pyridine methyl ester through acetic anhydride rearrangement; 3, hydrolyzing the acetic acid-4-pyridine methyl ester to obtain 4-pyridine methanol; 4, performing oxidation reaction on the 4-pyridine methanol to obtain the 4-pyridylaldehyde. After the synthetic method is adopted, the 4-methyl pyridine is used as the raw material, and the 4-pyridine methanol is obtained through N-oxidation, rearrangement and hydrolyzation and is further oxidized to obtain the 4-pyridylaldehyde. The synthetic method provided by the invention is high in total yield, low in raw material price, short in reaction time, mild in condition, and simple in process operation.
Catalytic deoxygenation of pyridine N-oxides with N-fused porphyrin rhenium complexes
Toganoh, Motoki,Fujino, Keitaro,Ikeda, Shinya,Furuta, Hiroyuki
, p. 1488 - 1491 (2008/09/18)
Deoxygenation reactions of pyridine N-oxide derivatives catalyzed by N-fused porphyrin rhenium(VII) trioxo complexes are developed, affording the corresponding pyridine derivatives in quantitative yields with excellent turnover numbers up to 340,000.
Deoxygenation of pyridine N-oxides by palladium-catalysed transfer oxidation of trialkylamines
Fuentes, José A.,Clarke, Matthew L.
scheme or table, p. 2579 - 2582 (2009/04/16)
A convenient and chemoselective method for deoxygenation of pyridine TV-oxide derivatives by transfer oxidation of triethylamine-catalysed by [Pd(OAc)2]/dppf is described.
Deoxygenation of N-oxides with triphenylphosphine, catalyzed by dichlorodioxomolybdenum(VI)
Sanz, Roberto,Escribano, Jaime,Fernández, Yolanda,Aguado, Rafael,Pedrosa, María R.,Arnáiz, Francisco J.
, p. 1389 - 1392 (2007/10/03)
Chemoselective deoxygenation of N-oxides was carried out under mild conditions with common phosphines in the presence of dichlorodioxomolybdenum(VI) . Georg Thieme Verlag Stuttgart.
A comparison of the thermal decomposition of nitramines and difluoramines
Oxley,Smith,Zhang,Bedford
, p. 579 - 590 (2007/10/03)
The decomposition rates and product distributions of a number of nitro- and difluoramino-substituted six-membered rings were compared: nitrocyclohexane (I); 1,1-dinitro-cyclohexane (II); 1,1,4,4-tetranitrocyclohexane (III), 1,1,4,4-tetrakis(difluoramino)cyclohexane (IV); 1,4-dinitropiperazine (V); 1,4,4-trinitropiperidine (VI), and 4,4-bis(difluoramino)-1-nitropiperidine (VII). The study suggested the following order for susceptibility to decomposition: N-NO2 > C-(NO2)2 > C-(NF2)2 The difference in bond energies among the compounds is small. Geminal bis(difluoramino) compounds appeared to be somewhat more stable than the corresponding gem-dinitro compounds though they released more heat during decomposition. Where a nitramine functionality was present, the nitroso analogue was observed as a major decomposition product. The decomposition of gem-bis(difluoramino) and gem-dinitro compounds exhibited similarities. Both experienced loss of one geminal NX2 group followed by the rearrangement of the remaining NX2. Where X was oxygen, loss of the initial nitro by homolysis was favored; rearrangement of the remaining nitro followed by homolysis of NO resulted in a C=O bond. Where X was fluorine, the initial difluoramino may have been lost as HNF2. The remaining difluoramino reacted by losing fluorine, leaving C=NF or by losing HNF, resulting in =C-F; the latter was mainly observed.
