The reaction of N-heteroaromatic compounds, such as 2-aryl-pyrrole, benzimidazole, imidazole, indole, and pyrazole derivatives, with alkynes in the presence of a catalytic amount of a nickel complex results in C–H/N–H oxidative annulation. The reaction shows a high functional group compatibility. While both Ni(0) and Ni(II) complexes show a high catalytic activity, Ni(0) is proposed as a key catalytic
N-杂芳族化合物(例如 2-芳基吡咯、苯并咪唑、咪唑、吲哚和吡唑衍生物)与炔烃在催化量的镍配合物存在下发生反应,导致 C-H/N-H 氧化成环。该反应表现出较高的官能团相容性。虽然Ni(0)和Ni( II )配合物均表现出高催化活性,但Ni(0)被认为是主催化循环中的关键催化物种。在 Ni( II ) 体系的情况下,反应的进行需要催化量的强碱(例如 KOBu t )的存在。与此形成鲜明对比的是,Ni(0) 系统不需要碱。所提出的机制得到了 DFT 研究的支持。
Combined Experimental and Computational Investigations of Rhodium- and Ruthenium-Catalyzed C–H Functionalization of Pyrazoles with Alkynes
作者:Andrés G. Algarra、Warren B. Cross、David L. Davies、Qudsia Khamker、Stuart A. Macgregor、Claire L. McMullin、Kuldip Singh
DOI:10.1021/jo402592z
日期:2014.3.7
which then undergoes C–H bond cleavage via proton transfer to acetate. For the reaction of 3-phenyl-5-methylpyrazole with 4-octyne kH/kD = 2.7 ± 0.5 indicating that C–H bond cleavage is rate limiting in this case. However, H/D exchangestudies, both with and without added alkyne, suggest that the migratory insertion transition state is close in energy to that for C–H bond cleavage. In order to model
关于炔烃与3-芳基吡唑在[Rh(MeCN)3 Cp *] [PF 6 ] 2和[RuCl 2(p- cymene)] 2催化剂上偶联机理的详细实验和计算研究已报道。密度泛函理论(DFT)的计算表明一种机制涉及连续的N–H和C–H键激活,HOAc /炔烃交换,迁移插入和C–N还原偶联。对于铑,C-H键活化是包括κ一个两步过程2 -κ 1个位移乙酸,得到agostic中间体,其然后通过质子转移到乙酸经历C-H键断裂。用于3-苯基-5-甲基吡唑与4-辛炔的反应k H / k D = 2.7±0.5,表明在这种情况下C–H键的裂解是限速的。但是,无论是否添加炔烃,H / D交换研究都表明,迁移插入过渡态的能量与C–H键断裂的能量接近。为了正确地对此结果建模,DFT计算必须采用完整的实验系统,并包括色散效应的处理。在Ru(p -cymene)}处计算出明显更高的整体催化势垒,其限速过程仍为CH活化。然而,这是现在对应于κ一个一步法2
Rhodium(III)-Catalyzed Oxidative Coupling of 5-Aryl-1<i>H</i>-pyrazoles with Alkynes and Acrylates
作者:Xingwei Li、Miao Zhao
DOI:10.1021/jo201530r
日期:2011.10.21
[RhCp*Cl2]2-catalyzed oxidative coupling of 5-aryl-1H-pyrazoles with alkynes and acrylates has been achieved using Cu(OAc)2 as an oxidant. Coupling with alkynes afforded six-membered azacycles as a result of C–C and C–N coupling. Coupling with acrylates followed a process of diolefination and a subsequent aza-Michael cyclization.
Synthesis of pyrazolo[5,1-a]isoquinolines via C–H/N–H annulation of pyrazoles and alkynes with ruthenium(II) catalysts
作者:Keisham Sarjit Singh、Ramila R. Goankar、Kushal Banerjee、Werner Kaminsky
DOI:10.1007/s00706-023-03104-0
日期:2023.8
ruthenium(II)-catalyzed annulation of pyrazole derivatives with alkynes in the presence of Cu(OAc)2‧H2O and AgSbF6 producing pyrazolo[5,1-a]isoquinolines. The reaction proceeded efficiently in water under nitrogen atmosphere leading to an excellent yield of the products. This annulation process can also be performed in alcohol at a lower temperature without Cu(OAc)2‧H2O and silversalt but in the presence of a carboxylate