Cationic Rhodium(I)/Segphos-Catalyzed Cycloisomerization of 1,6- and 1,7-Diynes in the Presence of 1,2-Cyclohexanedione
摘要:
We have developed the first catalytic cycloisomerization of 1,6- and 1,7-diynes leading to trienes and vinylpyrroles by using a cationic rhodium(I)/Segphos complex (2.5-10 mol %) and 1,2-cyclohexanedione (100 mol %). 1,2-Cyclohexanedione may effectively occupy vacant coordination sites and thus promote the present cycloisomerization.
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。
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
We found that the combination of [Ir(cod)Cl]2 and rac-BINAP served as an efficient catalyst for the [2+2+2] cycloaddition of 2,7-nonadiyne derivatives and related compounds with alkynyl ketones and alkynyl esters. The corresponding products were obtained in high yields under mild reaction conditions.
Bridging a gap: A cationic rhodium(I)/ligand complex catalyzes the title reaction of alkynes and amide‐linked 1,5‐dienes, leading to bridged multicyclic compounds, with high chemo‐, regio‐, and enantioselectivity (see scheme; Bn=benzyl).
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.