Efficient Nickel-Catalyzed [2 + 2 + 2] Cycloaddition of CO2 and Diynes
摘要:
A mild and general route for preparing 2-pyrones from CO2 and diynes is described. Under only 1 atm of CO2, excellent yields of pyrone are obtained using catalytic amounts of Ni(COD)2 and imidazolylidene ligand, IPr. In addition, stoichiometric reactions between the isolated complex Ni(IPr)2, diynes, and CO2 suggest that the pathway involves initial reaction with CO2 as the key step.
successfully applied to the synthesis of terpyridine and quinquepyridine. This chemistry was extended to a new and efficient synthesis of oligoheteroarenes. Five aromatic or heteroaromatic rings were connected in a single operation. [Ir(cod)Cl](2)/chiral diphosphine catalyst can be applied to enantioselective synthesis. Kinetic resolution of the racemic secondary benzyl nitrile catalyzed by [Ir(cod)Cl](2)/SEGPHOS
[Ir(cod)Cl](2)/DPPF 或 BINAP 有效地催化 α,ω-二炔与腈的环加成反应生成吡啶。该反应可以适应范围很广的腈。脂肪族和芳香族腈均与 α,ω-二炔顺利反应生成吡啶。十当量的未活化脂族腈足以得到高产率的产物。带有缩醛或氨基部分的脂肪腈可用于该反应。实现了带有两个不同内部炔烃部分的不对称二炔的高度区域选择性环加成。考虑到环戊二烯中α-位的不同反应性,可以合理地解释观察到的区域选择性。区域选择性环加成成功地应用于三联吡啶和喹啉吡啶的合成。这种化学反应扩展到一种新的、有效的低聚杂芳烃合成方法。在一次操作中连接了五个芳环或杂芳环。[Ir(cod)Cl](2)/手性二膦催化剂可用于对映选择性合成。[Ir(cod)Cl](2)/SEGPHOS 催化的外消旋仲苄腈的动力学拆分得到了 80% ee 的中心碳手性吡啶。基于B3LYP水平的密度泛函计算分析了机理。
A Simple and Highly Efficient Iron Catalyst for a [2+2+2] Cycloaddition to Form Pyridines
作者:Chunxiang Wang、Xincheng Li、Fan Wu、Boshun Wan
DOI:10.1002/anie.201102001
日期:2011.7.25
Joined by iron: The ironcatalyst for the formation of pyridines at room temperature (see scheme), which was generated in situ from an inorganic iron salt and a diphosphine ligand, exhibited high reactivity and regioselectivity.
由铁连接:室温下由无机铁盐和二膦配体原位生成的用于形成吡啶的铁催化剂具有很高的反应性和区域选择性。
Iridium-Catalyzed [2+2+2] Cycloaddition of α,ω-Diynes with Isocyanates
作者:Gen Onodera、Mari Suto、Ryo Takeuchi
DOI:10.1021/jo202083z
日期:2012.1.20
This regioselectivity could be explained by the reaction of iridacyclopentadiene with a nitrogen–carbon double bond. The regioselectivity of the reaction of malonate-derived diyne was controlled by a steric effect, while that of the reaction of ester-tethered diyne was controlled by an electronic effect. [Ir(cod)Cl]2/chiral diphosphine catalyst could be used for the enantioselective synthesis of C–N
2-Acylpyridines were prepared by iridium-catalyzed [2 + 2 + 2] cycloaddition of α,ω-diynes with acyl cyanides. [Ir(cod)Cl]2/rac-BINAP or F-DPPE is an efficient catalyst for this reaction. The scope and limitations of this reaction have been disclosed.
作者:Michael M. McCormick、Hung A. Duong、Gang Zuo、Janis Louie
DOI:10.1021/ja0508931
日期:2005.4.1
A mild and general route for preparing pyridines from nitriles and diynes is described. Ni/imidazolyidene complexes were used to mediate cyclization alkynes and both aryl and alkyl nitriles at ambient temperature. In addition, the efficacy of this protocol allows for the preparation of a fused seven-membered pyridone and for intermolecular cyclizations. When an asymmetrical diyne was employed, cyclization