ChemInform Abstract: Synthesis of Aryl‐Substituted Pyridines by Liquid‐Phase Condensation of Aldehydes with Urea Catalyzed by Transition Metal Complexes.

Джемилев, У. М.; Selimov, F. A.; Akhmetov, A. Zh.; Фатыхов, А. А.

doi:10.1002/chin.198922197

Cited by 2 publications

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“…Thus, a liquid-phase condensation of benzaldehyde with alkylaldehydes and urea in the presence of twocomponent catalyst Co(2-ethylhexanoate) 2 -AlR 3 at 200 °C for 4 h leads to a mixture of 2,3,5-trisubstituted pyridines in total 80-95% yield. 100 The authors accentuate the target products 74 and 75 may be produced in a joint condensation of benzaldehyde with alkylaldehydes. A formation of arylpyridines in condensation of benzaldehyde with urea under the set conditions is not observed.…”

Section: Pyridine Synthesis By Liquid-phase Condensation Of Aldehydesmentioning

confidence: 99%

Metal complex catalysis in a synthesis of pyridine bases

Джемилев¹,

Selimov²,

Толстиков³

2002

Arkivoc

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The review systematizes for the first time literature data of the last 15 years on a synthesis of pyridine bases including those of natural structure with the use of metal complex catalysts. The catalyzed by complexes of transition metals (Co, Ni, Pd, Zr) and rare-earth elements reactions of heterocyclization of acetylenes with nitriles, liquid phase condensation of aldehydes with amines, linear and cyclic oligomerization of vinylpyridines with 1,3-dienes and condensation of carbonic acid chloroanhydrides with olefins, acetylenes, tertiary alcohols to give substituted pyridines, quinolines and phenanthrolines of a set structure are considered. The mechanisms of molecule generation of pyridine bases in the presence of metal complex catalysts are discussed, and data on an effect of transition metal nature, initial monomer structure and reaction conditions on a reaction direction of a formation of six-membered nitrogen heterocycles are listed.

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Section: Pyridine Synthesis By Liquid-phase Condensation Of Aldehydesmentioning

confidence: 99%

Metal complex catalysis in a synthesis of pyridine bases

Джемилев¹,

Selimov²,

Толстиков³

2002

Arkivoc

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“…Also, they are prepared by condensation of alcohols, aldehydes, and ammonia in the presence of Lewis acids as catalysts and by the reaction of aldehydes with amines in the presence of heterogeneous catalysts such as cobalt catalysts. , Since preparation from alkynes and nitriles catalyzed by CpCo(PPh 3 ) 2 had been reported, pyridine derivatives were prepared in the presence of different transition metal catalysts such as Ti, Zr, Co, Rh, Pd, Ru, and Ta catalysts. ,− Of these transition metal catalysts, cobalt catalysts are extensively used as highly regioselective and active catalysts . For example, CoCl 2 ·6H 2 O, Cp 2 Co, CpCo(COD), cobalt vapor, and CpCoL 2 (Cp = cyclopentadienyl, COD = cyclooctadiene, L = CO, olefin, PR 3 ) are used for the preparation of pyridine derivatives from substituted alkynes and nitriles. − Using CpCo(PPh 3 ) 2 , pyridine derivatives were synthesized from substituted alkynes and nitriles as well as alkynes and isocyanates. , Vollhardt et al prepared annulated pyridines by cocyclotrimerization of diacetylenes with nitrile molecules catalyzed by CpCo(CO) 2 . Using the same catalyst, Saá et al synthesized 3-substituted bipyridines and symmetric 3,3′′-substituted terpyridines, which are important building blocks for supramolecular coordination compounds…”

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confidence: 99%

Theoretical Study on the Reaction Mechanism for the Formation of 2-Methylpyridine Cobalt(I) Complex from Cobaltacyclopentadiene and Acetonitrile

2009

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Isomerization from η 4 -pyridine complex, 5aS to the more stable one, 5bS.As shown in Figure 1, the acetonitrile molecule keeps the interaction with the coordinatively unsaturated cobaltacyclopentadiene to lead to 5aS, in which the C5 and N are the center of the coordination. However, there is more stable isomer of η 4 -pyridine complex 5bS. Thus, we investigated the isomerization of 5aS to 5bS. There are three sound paths for this isomerization. (i) The first path of isomerization.The optimized structures in this path and their ZPE-corrected energies relative to 2S and free acetonitrile are shown in Figure S1.As shown in Figure S1, 5aS isomerizes to another η 4 -pyridine complex 5cS via TS4a, with the activation barrier of 16.3 kcal/mol. TS4a can be considered as an η 2 -pyridine complex and pyridine ring has almost planar structure. The vibration mode with the imaginary frequency in TS4a is for pyridine ring rotation. Starting from TS4a, the IRC calculations, followed by optimization in the reactant and product directions lead to the two η 4 -pyridine complexes 5aS and 5cS with the four atoms of the pyridine ring coordinating to the cobalt atom (N, C1, C4 and C5 4 Figure S1. Profile for the first path of isomerization of 5aS to the most stable isomer η 4 -pyrdine Co(I) complex 5aS. All energies are ZPE-corrected and relative to 2S + CH 3 CN. All bond lengths are in Å.

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ChemInform Abstract: Synthesis of Aryl‐Substituted Pyridines by Liquid‐Phase Condensation of Aldehydes with Urea Catalyzed by Transition Metal Complexes.

Abstract: Cocondensation of the (het)aromatic aldehydes (I) with butyraldehyde (II) in the presence of urea (III) and a Co(II)/triethylaluminum catalytic system gives the (het)arylpyridines (IV), together with the diethylpropylpyridine (V).

Cited by 2 publications

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Metal complex catalysis in a synthesis of pyridine bases

Metal complex catalysis in a synthesis of pyridine bases

Theoretical Study on the Reaction Mechanism for the Formation of 2-Methylpyridine Cobalt(I) Complex from Cobaltacyclopentadiene and Acetonitrile

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