Devi Prarthana, Barry Sarah M, Houlihan Kate M, Murphy Michael J, Turner Peter, Jensen Paul, Rutledge Peter J
School of Chemistry F11, The University of Sydney, NSW 2006, Australia.
Sci Rep. 2015 May 8;5:9950. doi: 10.1038/srep09950.
Coupling picolinic acid (pyridine-2-carboxylic acid) and pyridine-2,6-dicarboxylic acid with N-alkylanilines affords a range of mono- and bis-amides in good to moderate yields. These amides are of interest for potential applications in catalysis, coordination chemistry and molecular devices. The reaction of picolinic acid with thionyl chloride to generate the acid chloride in situ leads not only to the N-alkyl-N-phenylpicolinamides as expected but also the corresponding 4-chloro-N-alkyl-N-phenylpicolinamides in the one pot. The two products are readily separated by column chromatography. Chlorinated products are not observed from the corresponding reactions of pyridine-2,6-dicarboxylic acid. X-Ray crystal structures for six of these compounds are described. These structures reveal a general preference for cis amide geometry in which the aromatic groups (N-phenyl and pyridyl) are cis to each other and the pyridine nitrogen anti to the carbonyl oxygen. Variable temperature 1H NMR experiments provide a window on amide bond isomerisation in solution.
将吡啶甲酸(吡啶 - 2 - 羧酸)和吡啶 - 2,6 - 二羧酸与N - 烷基苯胺偶联可得到一系列单酰胺和双酰胺,产率良好至中等。这些酰胺对于催化、配位化学和分子器件中的潜在应用具有重要意义。吡啶甲酸与亚硫酰氯反应原位生成酰氯,不仅按预期生成了N - 烷基 - N - 苯基吡啶甲酰胺,还在一锅反应中生成了相应的4 - 氯 - N - 烷基 - N - 苯基吡啶甲酰胺。这两种产物可通过柱色谱轻松分离。从吡啶 - 2,6 - 二羧酸的相应反应中未观察到氯化产物。描述了其中六种化合物的X射线晶体结构。这些结构揭示了顺式酰胺几何构型的普遍偏好,其中芳族基团(N - 苯基和吡啶基)彼此顺式排列,吡啶氮与羰基氧反式排列。变温1H NMR实验为溶液中的酰胺键异构化提供了一个窗口。