Microwave-assisted palladium-catalyzed C-C coupling versus nucleophilic aromatic substitution of hydrogen (S_N^H) in 5-bromopyrimidine by action of bithiophene and its analogues

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• 作者：Egor V. Verbitskiy^a ; ^{Verbitsky@ios.uran.ru} ; Ekaterina M. Cheprakova^a ; Ekaterina F. Zhilina^a ; Mikhail I. Kodess^a ; Marina A. Ezhikova^a ; Marina G. Pervova^a ; Pavel A. Slepukhin^a ; Julia O. Subbotina^a ; ^b ; Aleksandr V. Schepochkin^a ; Gennady L. Rusinov^a ; ^b ; Oleg N. Chupakhin^a ; ^b ; Valery N. Charushin^a ; ^b
• 关键词：C&ndash ; H bond activations ; Nucleophilic aromatic substitution of hydrogen ; Pyrimidines ; Palladium ; Microwave-assisted synthesis
• 刊名：Tetrahedron
• 出版年：2013
• 出版时间：24 June, 2013
• 年：2013
• 卷：69
• 期：25
• 页码：5164-5172
• 全文大小：2493 K

文摘

5-Bromopyrimidine reacts with 2,2¡ä-bithiophene, [2,2¡ä:5¡ä,2¡å]terthiophene and 2-phenylthiophene in the presence of a palladium catalyst to give 5-(het)aryl substituted pyrimidines due to the palladium-catalyzed aryl-aryl C-C coupling. However 5-bromo-4-(het)aryl-pyrimidines have been prepared from the same starting materials through the S_N^H-reaction catalyzed by a Lewis acid. Conditions for both types of reactions were optimized. All components of the reaction mixtures, including by-products, have been elucidated by gas-liquid chromatography/mass-spectrometry. Evidence for the structure of 4- and 5-bithiophenyl-substituted pyrimidines has first been obtained by means of X-ray crystallography analysis. Molecular orbital calculations (TDDFT), as well as the redox and optical measurements for all new compounds have also been performed.