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Acta Chim. Sinica ›› 2019, Vol. 77 ›› Issue (5): 418-421.DOI: 10.6023/A19020061 Previous Articles     Next Articles

Communication

无金属催化的吡啶C2位碳-氢键胺甲酰化反应合成吡啶甲酰胺

王昱赟, 刘云云   

  1. 江西师范大学化学化工学院 南昌 330022
  • 投稿日期:2019-02-11 发布日期:2019-04-09
  • 通讯作者: 刘云云 E-mail:chemliuyunyun@jxnu.edu.cn
  • 基金资助:

    项目受国家自然科学基金（No.21562024）资助.

Metal-Free C2-H Aminocarbonylation of Pyridines for the Synthesis of Picolinamides

Wang Yuyun, Liu Yunyun   

  1. College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022
  • Received:2019-02-11 Published:2019-04-09
  • Contact: 10.6023/A19020061 E-mail:chemliuyunyun@jxnu.edu.cn
  • Supported by:

    Project supported by the National Natural Science Foundation of China (No. 21562024).

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Supporting Info.

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In this paper, a metal-free catalytic method for synthesis of 2-picolinamide derivatives is reported. Under the promotion of proton acid, simple pyridines react with isocyanides to provide 2-picolinamides by means of the aminocarbonylation of the aryl C-H bond in the C2 position of pyridines. The product formation involves in the electrophilic addition of isocyanide to pyridine ring, hydrolysis and the oxidative aromatization regenerating pyridine ring in the presence of Di-t-butyl peroxide (DTBP) and oxalic acid dihydrate. Control experiments in the optimization section disclose the fact that the proton acid and oxidant are both indispensable for this C-H bond aminocarbonylation reaction. Generally, the synthetic reactions run smoothly under air atmosphere by heating all the substrates and reagents in one-pot at 100℃. The pyridine substrates containing methyl, t-butyl, cyclic dialkyl, methoxyl, halogen substituents at different site of the pyridine ring have displayed fine tolerance to the synthesis of corresponding products with diverse substructures in the pyridine ring. On the other hand, both alkyl and aryl functionalized isocyanides have also been found applicable to this synthetic protocol to provide 2-picolinamides containing correspondingly various N-alkyl and N-aryl fragment. The primary results indicate that the stability of the isocyanide substrate evidently influence the reaction result. The reactions employing relatively more stable 2,6-dimethylphenyl isocyanide give corresponding products with higher yield than those ones using other isocyanides. Comparing with those reported methods employing transition metal catalyst such as silver or palladium salt to activate the C2-H bond in pyridines for the synthesis of analogous products, the present method benefits from the distinctive features of totally metal-free catalysis, broad substrate tolerance, specific regioselectivity in transforming C2-H bond, and high atom economy. Therefore, such a synthetic method will reasonably be a practical approach in complementing those already known strategies for the synthesis of structurally diverse and useful 2-picolinamide scaffolds.

Key words: metal-free, pyridines, C-H bond, aminocarbonylation, 2-picolinamides