Palladium(II)-Catalyzed Direct Ortho Arylation of 4-Methyl-N-phenylpyridin-2-amines via C鈥揌 Activation/C鈥揅 Coupling and Synthetic Applications

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• 作者：Jean-Ho Chu ; Hao-Ping Huang ; Wen-Ting Hsu ; Shih-Tien Chen ; Ming-Jung Wu
• 刊名：Organometallics
• 出版年：2014
• 出版时间：March 10, 2014
• 年：2014
• 卷：33
• 期：5
• 页码：1190-1204
• 全文大小：650K
• 年卷期：v.33,no.5(March 10, 2014)
• ISSN：1520-6041

文摘

The direct ortho arylation of 4-methyl-N-phenylpyridin-2-amines via palladium(II)-catalyzed C鈥揌 activation is described. Treatment of 4-methyl-N-phenylpyridin-2-amine with potassium aryltrifluoroborate using 10 mol % of palladium(II) acetate as the catalyst, 2 equiv of copper(II) acetate as the oxidant, and 1 equiv of p-benzoquinone in tert-butyl alcohol gave ortho-arylated products in modest to excellent yields. This reaction shows good functional group compatibility. A series of ¹H NMR titration experiments and controlled experiments elucidating the reaction mechanism were carried out. The key intermediate, 4-methyl-N-phenylpyridin-2-amine palladacycle, was isolated and characterized by X-ray crystallography. The advanced transformations of ortho-phenylated 4-methyl-N-phenylpyridin-2-amine to N-(4-methylpyridin-2-yl)-9H-carbazole, biphenyl-2-amine, and 3-methyl-6-phenylpyrido[1,2-a]benzimidazole were successfully demonstrated as potential synthetic applications.