- Synthesis method of 2-bromopyrimidine
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The invention discloses a synthesis method of 2-bromopyrimidine, the route of which is shown as follows: the synthesis method of 2-bromopyrimidine provided by the invention comprises the following steps: carrying out oxidative addition on carbon-chlorine bonds of 2-chloropyrimidine through a metal catalyst, and then carrying out halogen exchange and reduction elimination to obtain the product 2-bromopyrimidine, and the reaction has the advantages of high operability, environment friendliness, convenience in regulation and control and the like.
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Paragraph 0011; 0035-0043
(2021/10/30)
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- Electron-deficient heteroarenium salts: An organocatalytic tool for activation of hydrogen peroxide in oxidations
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A series of monosubstituted pyrimidinium and pyrazinium triflates and 3,5-disubstituted pyridinium triflates were prepared and tested as simple catalysts of oxidations with hydrogen peroxide, using sulfoxidation as a model reaction. Their catalytic efficiency strongly depends on the type of substituent and is remarkable for derivatives with an electron-withdrawing group, showing reactivity comparable to that of flavinium salts which are the prominent organocatalysts for oxygenations. Because of their high stability and good accessibility, 4-(trifluoromethyl)pyrimidinium and 3,5-dinitropyridinium triflates are the catalysts of choice and were shown to catalyze oxidation of aliphatic and aromatic sulfides to sulfoxides, giving quantitative conversions, high preparative yields and excellent chemoselectivity. The high efficiency of electron-poor heteroarenium salts is rationalized by their ability to readily form adducts with nucleophiles, as documented by low pKR+ values (pKR+ red > -0.5 V). Hydrogen peroxide adducts formed in situ during catalytic oxidation act as substrate oxidizing agents. The Gibbs free energies of oxygen transfer from these heterocyclic hydroperoxides to thioanisole, obtained by calculations at the B3LYP/6-311++g(d,p) level, showed that they are much stronger oxidizing agents than alkyl hydroperoxides and in some cases are almost comparable to derivatives of flavin hydroperoxide acting as oxidizing agents in monooxygenases.
- ?turala, Ji?í,Bohá?ová, Soňa,Chudoba, Josef,Metelková, Radka,Cibulka, Radek
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p. 2676 - 2699
(2015/03/18)
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- Silyl-mediated halogen/halogen displacement in pyridines and other heterocycles
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Heating with bromotrimethylsilane converts 2-chloropyridine into 2-bromopyridine and 2-chloro-6-methylpyridine into 2-bromo-6-methylpyridine. Both 2-chloropyridines and 2-bromopyridines give the corresponding iodo compound when treated with in situ generated iodotrimethylsilane. Although 3- and 4-chloropyridine are completely inert, 2,4-dichloropyridine undergoes the halogen/halogen exchange simultaneously at the 2- and 4-position. Halogen displacement takes place exclusively at the 2-position with 2,3-dichloropyridine and 2,5-dichloropyridine. In agreement with the intermediacy of N-trimethylsilylpyridinium salts as a prerequisite for the occurrence of halogen exchange, neither 2-fluoropyridine and 2-fluoro-6-methylpyridine nor any 2,6-dihalopyridine reacts. Finally, bromine/chlorine and iodine/chlorine substitution can also be accomplished with 2-or 4-chloroquinoline, 1-chloroisoquinoline, 2-chloropyrimidine, chloropyrazine and 2,3-dichloroquinoxaline as substrates. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2002).
- Schlosser, Manfred,Cottet, Fabrice
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p. 4181 - 4184
(2007/10/03)
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- The synthesis of substituted pyridylpyrimidine fungicides using palladium-catalysed cross-coupling reactions
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Various substituted phenyl, pyridyl and benzyl zinc chlorides have been generated from the corresponding lithium or magnesium organometallic reagents. These have been cross-coupled with 2-(6-bromo-2- pyridyl)pyrimidines in the presence of tetrakis(triphenylphosphine)palladium(0) to produce a series of substituted pyridylpyrimidine fungicides in 32-99% yields. (C) 2000 Elsevier Science Ltd.
- Hargreaves, Stephanie L.,Pilkington, Brian L.,Russell, Sally E.,Worthington, Paul A.
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p. 1653 - 1656
(2007/10/03)
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