Synthesis of Aminopyridines and Aminopyridones by Cobalt-Catalyzed [2+2+2] Cycloadditions Involving Yne-Ynamides: Scope, Limitations, and Mechanistic Insights
Synthesis of Aminopyridines and Aminopyridones by Cobalt-Catalyzed [2+2+2] Cycloadditions Involving Yne-Ynamides: Scope, Limitations, and Mechanistic Insights
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DOI：
10.1002/chem.201103906
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发表时间：
2012-04-01
影响因子：
4.3
通讯作者：
Gandon, Vincent
中科院分区：
文献类型：
--
作者：
Garcia, Pierre;Evanno, Yannick;Gandon, Vincent
对钴催化的炔酰胺和腈之间的[2+2+2]环加成反应生成氨基吡啶进行了深入研究。大约 30 种具有广泛空间需求和电子特性的腈已被评估，其中一些为金属催化芳烃形成开辟了新的前景。特别是，使用[CpCo(CO)(dmfu)]（dmfu=富马酸二甲酯）作为预催化剂使得将缺电子腈掺入吡啶核成为可能。炔-炔酰胺处取代模式的修饰允许区域选择性转向3-或4-氨基吡啶。还简要研究了这种合成方法在使用炔酰胺和异氰酸酯构建氨基吡啶酮骨架中的应用。 DFT 计算表明，3-氨基吡啶是通过腈和中间体钴环戊二烯之间的正式[4+2]环加成形成的，而4-氨基吡啶则来自插入途径。
An in-depth study of the cobalt-catalyzed [2+2+2] cycloaddition between yne-ynamides and nitriles to afford aminopyridines has been carried out. About 30 nitriles exhibiting a broad range of steric demand and electronic properties have been evaluated, some of which open new perspectives in metal-catalyzed arene formation. In particular, the use of [CpCo(CO)(dmfu)] (dmfu=dimethyl fumarate) as a precatalyst made possible the incorporation of electron-deficient nitriles into the pyridine core. Modification of the substitution pattern at the yne-ynamide allows the regioselectivity to be switched toward 3- or 4-aminopyridines. Application of this synthetic methodology to the construction of the aminopyridone framework using a yne-ynamide and an isocyanate was also briefly examined. DFT computations suggest that 3-aminopyridines are formed by formal [4+2] cycloaddition between the nitrile and the intermediate cobaltacyclopentadiene, whereas 4-aminopyridines arise from an insertion pathway.