Enantioselective Preparation of 4-Substituted Cyclohexenes by Radical Fragmentation of Sulfoxides
摘要:
[GRAPHICS]Radical fragmentation of o-bromophenyl sulfoxides is reported. Starting from enantiomerically pure material, 4-substituted cyclohexene derivatives have been prepared with enantiomeric excesses between 70% and 86%, The key step of the process is a diastereoselective abstraction of a hydrogen atom by the initial aryl radical. The highest enantiomeric exesses have been obtained in the presence of aluminum Lewis acids.
A General Strategy for the Nickel-Catalyzed C−H Alkylation of Anilines
作者:Zhixiong Ruan、Sebastian Lackner、Lutz Ackermann
DOI:10.1002/anie.201510743
日期:2016.2.24
The C−H alkylation of aniline derivatives with both primary and secondary alkyl halides was achieved with a versatile nickel catalyst of a vicinal diamine ligand. Step‐economic access to functionalized 2‐pyrimidyl anilines, key structural motifs in anticancer drugs, is thus provided. The C−H functionalization proceeded through facile C−H activation and SET‐type C−X bond cleavage with the assistance
<i>N</i>-Acyl Amino Acid Ligands for Ruthenium(II)-Catalyzed <i>meta</i>-C–H <i>tert</i>-Alkylation with Removable Auxiliaries
作者:Jie Li、Svenja Warratz、Daniel Zell、Suman De Sarkar、Eloisa Eriko Ishikawa、Lutz Ackermann
DOI:10.1021/jacs.5b08435
日期:2015.11.4
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
酰化氨基酸配体使钌 (II) 催化的 CH 官能化具有出色的元选择性。源自单保护氨基酸 (MPAA) 的钌 (II) 配合物的出色催化活性为第一个具有可移除导向基团的钌催化元功能化奠定了基础。因此,可以使用间烷基化苯胺,这是很难通过其他直接苯胺官能化方法制备的。多功能钌 (II)-MPAA 的稳健性通过在苯胺衍生物以及吡啶基、嘧啶基和吡唑基取代的芳烃上用叔烷基卤化物进行远程 CH 转化具有挑战性来体现。详细的机理研究为最初的可逆 CH 钌化提供了强有力的支持,然后通过均裂键裂解激活 SET 型 C-Hal。动力学分析通过反应速率对钌催化剂浓度的不寻常的二阶依赖性证实了这一假设。总体而言,该报告强调了源自酰化氨基酸的钌配合物的卓越催化活性,这应该证明有助于超越远程功能化的 CH 活化化学。