Silver-Mediated C–H Activation: Oxidative Coupling/Cyclization of N-Arylimines and Alkynes for the Synthesis of Quinolines
摘要:
A silver-mediated tandem protocol for the synthesis of quinolines involving the oxidative coupling/cyclization of N-arylimines and alkynes has been developed. We demonstrated that scenario-dependent metalation could occur either at the ortho C-H bond of an N-arylimine through protonation-driven enhancement of acidity or at the terminal C-H bond of an alkyne by virtue of the carbophilic pi-acidity of silver. The diverse set of mechanistic manifolds implemented with a single type of experimental protocol points toward the importance of stringent reactivity analysis of each individual potentially reactive molecular site. Importantly, the direct arene C H bond activation provides a unique and distinct mechanistic handle for the expansion of reactivity paradigms for silver. As expected, the protocol allows for the incorporation of both internal and terminal alkynes into the products, and in addition, both electron-withdrawing and -donating groups are tolerated on N-arylimines, thus enabling the vast expansion of substituent architectures on quinoline framework. Further, an intriguing phenomenon of structural isomerization and chemical bond cleavage has been observed for aliphatic internal alkynes.
One-Pot Catalytic Approach for the Selective Aerobic Synthesis of Imines from Alcohols and Amines Using Efficient Arene Diruthenium(II) Catalysts under Mild Conditions
作者:Sundar Saranya、Rengan Ramesh、Jan Grzegorz Małecki
DOI:10.1002/ejoc.201701408
日期:2017.12.8
A green and efficient catalytic approach for the selective synthesis of imines in air at room temperature was achieved with the aid of newly synthesised diruthenium(II) complexes [(η6-p-cymene)2Ru2Cl2(µ-L)] containing substituted 1,2-diacylhydrazine ligands. All the new complexes were fully characterised by analytical and spectroscopic techniques. The solid-state structure of a representative complex
借助新合成的含有取代 1,2 的二钌 (II) 配合物 [(η6-p-cymene)2Ru2Cl2(μ-L)],实现了一种绿色高效的室温下在空气中选择性合成亚胺的催化方法-二酰基肼配体。通过分析和光谱技术对所有新复合物进行了充分表征。通过单晶 X 射线衍射分析解决了代表性复合物的固态结构。二钌 (II) 配合物还可将醇选择性有氧氧化为醛。催化反应在作为绿色廉价氧化剂的空气存在下进行,并释放出作为唯一副产物的水。提出了亚胺形成的合理机制,据信这是通过醛中间体进行的。
Phosphine ligand-free RuCl3-catalyzed reductive N-alkylation of aryl nitro compounds
作者:Da-Wei Tan、Hong-Xi Li、David James Young、Jian-Ping Lang
DOI:10.1016/j.tet.2016.05.036
日期:2016.7
efficiently catalyses the reductive N-alkylation of aryl nitrocompounds with alcohols using bio-based glycerol as the hydrogen source and without the need for any added solvents. The reaction can be easily manipulated to produce either imines or secondary amines in high yields. RuCl3-catalyzed reductive N-alkylation of nitroarenes with alcohols affords the corresponding imine products in good to excellent
Abstract A simple and efficient method for preparation of imines by the oxidative coupling of benzyl alcohols with aromatic amines or aliphatic amines was developed. The reaction was catalyzed by 9-azabicyclo[3.3.1]nonan-N-oxyl (ABNO)/KOH with air as the economic and green oxidant. Under the optimal reaction conditions, a variety of imines were obtained in 80%-96% isolated yields.
A new Mn(II) metal–organicframework (MOF) 1 was synthesized by the combination of 4,4,4-trifluoro-1-(4-(pyridin-4-yl)phenyl)butane-1,3-dione (L) and Mn(OAc)2 in solution. 1 features a threefold-interpenetrating NbO net containing honeycomb-like channels, in which the opposite Mn(II)···Mn(II) distance is 23.5075(10) Å. Furthermore, 1 can be an idealplatform to support Pd–Au bimetallic alloy nanoparticles
core/shell quantum dots (QDs) can be used as stable and highly active photoredoxcatalysts for efficient transferhydrogenation of imines to amines with thiophenol as a hydrogen atom donor. This reaction proceeds via a proton-coupled electron transfer (PCET) from the QDs conduction band to the protonated imine followed by hydrogen atom transfer from the thiophenol to the α-aminoalkyl radical. This precious