N-Acyl Amino Acid Ligands for Ruthenium(II)-Catalyzed meta-C-H tert-Alkylation with Removable Auxiliaries
N-Acyl Amino Acid Ligands for Ruthenium(II)-Catalyzed meta-C-H tert-Alkylation with Removable Auxiliaries
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DOI：
10.1021/jacs.5b08435
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发表时间：
2015-11-04
影响因子：
15
通讯作者：
Ackermann, Lutz
中科院分区：
文献类型：
--
作者：
Li, Jie;Warratz, Svenja;Ackermann, Lutz
酰化的氨基酸配体使得钌（II）催化的C-H官能化具有优异的间位选择性水平。来自单保护氨基酸（MPAA）的钌（II）络合物的突出催化活性为第一个具有可移除导向基团的钌催化的间位官能化设置了阶段。因此，可以获得间烷基化苯胺，这是难以通过其他方式的直接苯胺官能化制备。多功能钌（II）MPAA的强大的性质反映了挑战性的远程C-H转换与叔烷基卤苯胺衍生物以及吡啶基，嘧啶基，和吡唑基取代的芳烃。详细的机制研究提供了强有力的支持，最初的可逆C-H双烯化，然后通过SET型的C-Hal活化，通过均裂键裂解。动力学分析证实了这一假设，通过一个不寻常的二阶依赖的钌催化剂浓度的反应速率。总的来说，这份报告强调了特殊的催化活性的钌络合物来自酰化的氨基酸，这应该证明有助于C-H活化化学超越远程功能化。
Acylated amino acid ligands enabled ruthenium(II)-catalyzed C-H functionalizations with excellent levels of meta-selectivity. The outstanding catalytic activity of the ruthenium(II) complexes derived from monoprotected amino acids (MPAA) set the stage for the first ruthenium-catalyzed meta-functionalizations with removable directing groups. Thereby, meta-alkylated anilines could be accessed, which are difficult to prepare by other means of direct aniline functionalizations. The robust nature of the versatile ruthenium(II) MPAA was reflected by challenging remote C-H transformations with tertiary alkyl halides on aniline derivatives as well as on pyridyl-, pyrimidyl-, and pyrazolyl-substituted arenes. Detailed mechanistic studies provided strong support for an initial reversible C-H ruthenation, followed by a SET-type C-Hal activation through homolytic bond cleavage. Kinetic analyses confirmed this hypothesis through an unusual second-order dependence of the reaction rate on the ruthenium catalyst concentration. Overall, this report highlights the exceptional catalytic activity of ruthenium complexes derived from acylated amino acids, which should prove instrumental for C-H activation chemistry beyond remote functionalization.