Enantioselective synthesis of tunable chiral pyridine–aminophosphine ligands and their applications in asymmetric hydrogenation
作者:Youran Liu、Fei Chen、Yan-Mei He、Chenghao Li、Qing-Hua Fan
DOI:10.1039/c9ob00770a
日期:——
ligands were enantioselectively synthesized based on chiral 2-(pyridin-2-yl)-substituted 1,2,3,4-tetrahydroquinoline scaffolds, which were obtained in high yields and with excellent enantioselectivities via ruthenium-catalyzed asymmetric hydrogenation of 2-(pyridin-2-yl)quinolines. The protocol features a wide substrate scope and mild reaction conditions, enabling scalable synthesis. These chiral
基于手性2-(吡啶-2-基)-取代的1,2,3,4-四氢喹啉骨架,对映选择性地合成了一个可调谐的手性吡啶-氨基膦配体的小型文库,该文库以高收率和优异的对映选择性通过钌催化的2-(吡啶-2-基)喹啉不对称氢化。该方案具有广泛的底物范围和温和的反应条件,可实现可扩展的合成。这些手性P,N配体已成功应用于Ir催化的基准烯烃和具有挑战性的七元环亚胺(包括苯并ze庚因和苯并二氮杂卓)的不对称加氢反应。在2,4-二芳基-3 H-苯并[ b ]氮杂和2,4-不对称氢化反应中,具有出色的对映和非对映选择性(高达99%ee和> 20:1 dr)和/或前所未有的化学选择性。二芳基-3 H-苯并[ b ] [1,4]二氮杂pine。
Visible-Light-Induced C2 Alkylation of Pyridine <i>N</i>-Oxides
作者:Wen-Man Zhang、Jian-Jun Dai、Jun Xu、Hua-Jian Xu
DOI:10.1021/acs.joc.6b02891
日期:2017.2.17
A photoredox catalytic method has been developed for the direct C2 alkylation of pyridineN-oxides. This reaction is compatible with a range of synthetically relevant functional groups for providing efficient synthesis of a variety of C2-alkylated pyridineN-oxides under mild conditions. Mechanistic studies are consistent with the generation of a radical intermediate along the reaction pathway.
The microwave-assisted ortho-alkylation of azine N-oxides with N-tosylhydrazones catalyzed by copper(<scp>i</scp>) iodide
作者:Abadh Kishor Jha、Nidhi Jain
DOI:10.1039/c5cc07833d
日期:——
A regioselective direct ortho-alkylation of azine N-oxides has been achieved under ligand-free conditions using copper(i) iodide and microwave conditions.
Copper-catalyzed cross-dehydrogenative coupling of pyridine N-oxides with cyclic ethers
作者:Ebrahim Kianmehr、Nasser Faghih、Saeed Karaji、Yousef Amiri Lomedasht、Khalid Mohammed Khan
DOI:10.1016/j.jorganchem.2015.10.010
日期:2016.1
Highly chemo- and regioselective synthesis of 2-alkylpyridine N-oxides from pyridine N-oxides and cyclic ethers has been developed through copper-catalyzed CDC reactions using CuO as the catalyst under mild reaction conditions. Optimization study showed that, K2S2O8 is the best oxidant for the reaction and the mechanistic study proved the radical pathway for this transformation. It was found that the
通过铜催化的CDC反应,使用CuO作为催化剂,在温和的反应条件下,由吡啶的N-氧化物和环状醚开发了高度化学和区域选择性的2-烷基吡啶N-氧化物的合成方法。优化研究表明,K 2 S 2 O 8是反应的最佳氧化剂,机理研究证明了该转化的自由基途径。发现具有给电子或吸电子基团的底物可以平滑地反应以提供所需的产物。
Palladium-Catalyzed C–H Activation/Cross-Coupling of Pyridine <i>N</i>-Oxides with Nonactivated Secondary Alkyl Bromides
作者:Bin Xiao、Zhao-Jing Liu、Lei Liu、Yao Fu
DOI:10.1021/ja3113752
日期:2013.1.16
activation/C-C cross-coupling reaction has been found to occur between pyridine N-oxides and general nonactivated secondary and even tertiary alkylbromides. It provides a practically useful approach for the synthesis of alkylated pyridine derivatives. Experimental observations indicated that the C-Br cleavage step involves a radical-type process. Thus, the title reaction provides a rather extraordinary