The Ru(dppbsa)-catalyzed reductive amination of ketones with nitroarenes and nitriles using H2 as the environmentally benign hydrogen surrogate is developed in this study. Cross-experiments demonstrated that both reactions are initiated by the reduction of nitroarenes or nitriles to the corresponding amines, followed by condensation with ketones to give imines and thereafter hydrogenation. However
本研究开发了使用 H 2作为环境友好型氢替代物的 Ru(dppbsa) 催化的酮与硝基芳烃和腈的还原胺化反应。交叉实验表明,这两个反应都是通过将硝基芳烃或腈还原成相应的胺,然后与酮缩合得到亚胺,然后氢化来引发的。然而,不能完全排除在硝基芳烃或腈还原过程中形成氨基连接的 Ru 络合物,然后进行原位亲核 C-N 偶联的途径。这种新开发的通用方法具有良好的官能团耐受性,为构建仲胺基序的均相催化剂提供了一个新颖的设计平台。
Taking the F out of FLP: Simple Lewis Acid–Base Pairs for Mild Reductions with Neutral Boranes via Borenium Ion Catalysis
作者:Patrick Eisenberger、Adrian M. Bailey、Cathleen M. Crudden
DOI:10.1021/ja307374j
日期:2012.10.24
Discrete three-coordinate borenium salts 1c and 1d are accessed by cooperative Lewis acid-base pair-mediated heterolytic splitting of the B-H bond in pinacolborane by B(C6F5)(3)center dot DABCO and Ph3C+/DABCO, respectively. The resulting salts are competent catalysts in the reduction of a broad range of imines and can be generated in situ. Moreover, a mechanistic framework for borenium catalysis based on experimental evidence is proposed. The reaction is suggested to proceed by borenium activation of the imine substrate followed by counterintuitive hydride delivery from HBPin (with the assistance of DABCO) rather than from the HB(C6F5)(3)(-) anion, contrary to typical mechanisms of reduction in FLP systems.
A Highly Enantioselective Organocatalytic Method for Reduction of Aromatic
<i>N</i>
‐Alkyl Ketimines
作者:Chao Wang、Xinjun Wu、Li Zhou、Jian Sun
DOI:10.1002/chem.200801479
日期:2008.10.10
Trading N and O. Part 3: Synthesis of 1,2,3,4-tetrahydroisoquinolines from α-hydroxy-β-amino esters
作者:Stephen G. Davies、Ai M. Fletcher、Aileen B. Frost、Matthew S. Kennedy、Paul M. Roberts、James E. Thomson
DOI:10.1016/j.tet.2016.03.008
日期:2016.4
A range of enantiopure 1,2,3,4-tetrahydroisoquinolines have been prepared directly from α-hydroxy-β-amino esters. Activation of the α-hydroxy group upon treatment with Tf2O and 2,6-di-tert-butyl-4-methylpyridine promotes aziridinium formation, which is then followed by rupture of the C(3)–N bond and Friedel–Crafts alkylation-type cyclisation of an N-benzyl moiety onto the resultant benzylic carbenium