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。
Cationic Rhodium(I)/H<sub>8</sub>-binap Complex Catalyzed [2+2+2] Cycloadditions of 1,6- and 1,7-Diynes with Carbonyl Compounds
作者:Yousuke Otake、Rie Tanaka、Ken Tanaka
DOI:10.1002/ejoc.200900185
日期:2009.6
catalyzes [2+2+2] cycloadditions of a variety of 1,6- and 1,7-diynes with both electron-deficient and electron-rich carbonyl compounds, leading to dienones in high yield under mild reaction conditions. In the reactions with acyl phosphonates, the reactivity of 1,6- and 1,7-diynes was highly dependent on their own structures. The addition of chelating diethyl oxalate effectively promoted the [2+2+2] cycloadditions
Cyclobutanones underwent a formal [4 + 2 + 2] annulation reaction with 1,6- and 1,7-diynes in the presence of nickel(0) catalysts to provide bicyclic eight-membered ring ketones. The annulation reaction proceeds through a ring-expansion of oxanickelacycloheptadiene via beta-carbon elimination to form a nine-membered nickelacycle. This reaction employing cyclobutanones as a C4 unit constructs cyclooctadienone
An Expeditious Route to Eight‐Membered Heterocycles By Nickel‐Catalyzed Cycloaddition: Low‐Temperature CC Bond Cleavage
作者:Puneet Kumar、Kainan Zhang、Janis Louie
DOI:10.1002/anie.201203521
日期:2012.8.20
diynes undergo a cycloaddition reaction catalyzed by Ni/IPr to give dihydroazocine compounds (see scheme; IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazolidene). The reaction involves a challenging CC bond cleavage step, yet, surprisingly, proceeds at low temperature.
Nickel-Catalyzed [4+2+2]-Type Annulation Reaction of Cyclobutanones with Diynes and Enynes
作者:Shinji Ashida、Masahiro Murakami
DOI:10.1246/bcsj.81.885
日期:2008.7.15
In the presence of a nickel(0) catalyst, cyclobutanones reacted with diynes to produce bicyclic eight-membered ring ketones. Cyclobutanones acted as a C4 unit in the formal [4+2+2]-type annulation reaction, which proceeded through a ring-expansion of a spirocyclic seven-membered oxanickelacycle to a nine-membered nickelacycle via β-carbon elimination. A similar annulation reaction was also examined with enynes.