1124-33-0Relevant articles and documents
Single component N-O chelated arylnickel(II) complexes as ethene polymerisation and CO/ethene copolymerisation catalysts. Examples of ligand induced changes to the reaction pathway
Desjardins, Sylvie Y.,Cavell, Kingsley J.,Hoare, Jason L.,Skelton, Brian W.,Sobolev, Alexander N.,White, Allan H.,Keim, Wilhelm
, p. 163 - 174 (1997)
Arylnickel(II) phosphine complexes containing substituted N-O bidentate ligands, of the type [NiR(N-O)L] [N-O = 4-nitropyridine-2-carboxylate (4-NO2-pyca), R = 0-tolyl, L = PPh3; N-O = 2-pyrazinecarboxylate (pyzca), R = 0-tolyl, L = PPh3; and N-O = 4-methoxypyridine-2-carboxylate (4-MeO-pyca), R = 0-tolyl, L = PPh3] have been prepared and characterised. Single crystal X-ray studies of the complexes [Ni(0-tolyl)(pyca)PPh3], 1, and the isomorphous analogue [Ni(0-tolyl)(4-NO2-pyca)PPh3], 3, show the expected square planar coordination about the nickel centres, with the pyridine nitrogens being trans to the phosphine ligand for both compounds. The coordination spheres of the two complexes are very similar, no elongation of the Ni-N bond for complex 3, which contains the 4-NO2-pyca ligand, being evident. In complex 3 the 0-tolyl ligand is disordered over two sites indicating the presence, in the solid state, of two conformers in which the 0-methyl groups of 0-tolyl are located to either side of the coordination plane. The complexes with substituted pyca ligands form single component catalysts for the conversion of ethene to high molecular weight polyethene and for the copolymerisation of ethene and carbon monoxide to polyketone under mild conditions. The nature of the product, whether predominantly high molecular weight polymer or a mixture of polymer and lower oligomer, is dependent on the basicity of the N-O chelate ligand. From an NMR study of the effect of added ethene on the complex [Ni(0-tolyl)(4-NO2-pyca)PPh3], a mechanism involving alkene promoted ligand dissociation is suggested.
Solvent- and halide-free synthesis of pyridine-2-yl substituted ureas through facile C-H functionalization of pyridine: N -oxides
Rassadin, Valentin A.,Zimin, Dmitry P.,Raskil'dina, Gulnara Z.,Ivanov, Alexander Yu.,Boyarskiy, Vadim P.,Zlotskii, Semen S.,Kukushkin, Vadim Yu.
supporting information, p. 6630 - 6636 (2018/03/01)
A novel solvent- and halide-free atom-economical synthesis of practically useful pyridine-2-yl substituted ureas utilizes easily accessible or commercially available pyridine N-oxides (PyO) and dialkylcyanamides. The observed C-H functionalization of PyO is suitable for the good-to-high yielding synthesis of a wide range of pyridine-2-yl substituted ureas featuring electron donating and electron withdrawing, sensitive, or even fugitive functional groups at any position of the pyridine ring (63-92%; 19 examples). In the cases of 3-substituted PyO, the C-H functionalization occurs regioselectively providing a route for facile generation of ureas bearing a 5-substituted pyridine-2-yl moiety.
A two-step continuous flow synthesis of 4-nitropyridine
Wan, Zhidong,Fang, Zheng,Yang, Zhao,Liu, Chengkou,Gu, Jiajia,Guo, Kai
, p. 209 - 212 (2015/06/02)
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.
PROCESS FOR THE PREPARATION OF FAMPRIDINE
-
Page/Page column 13, (2011/10/03)
The present invention relates to a process for the preparation of substantially pure fampridine compound of structural formula (I), (II), (III) comprising nitrifying pyridine-N-oxide hydrochloride with suitable nitrating agent; reducing with suitable reducing agent and purifying by recrystallizing in water followed by treating with an alkyl acetate solvent.
