Rh-catalysed [5 + 1] cycloaddition of allenylcyclopropanes and CO: reaction development and application to the formal synthesis of (−)-galanthamine
作者:Cheng-Hang Liu、Zhi-Xiang Yu
DOI:10.1039/c6ob00660d
日期:——
A Rh-catalysed [5 + 1] cycloaddition of allenylcyclopropanes and CO has been developed to synthesize functionalized 2-methylidene-3,4-cyclohexenones. The scope of this methodology has been investigated, showing that various functional groups can be tolerated. Both di- and tri-substituted allenylcyclopropanes can be applied to this cycloaddition and the [5 + 1] cycloadducts with the E configuration
A Ni‐catalyzed [2+2+2] cycloaddition reaction between allene‐ynes and various mono‐, di‐ and tri‐substituted allenes is described. This protocol effectively differentiates allenyl π components and shows broad substrate generality to give highly functionalized carbocycles. A DFT study played a key role in revealing a detailed reaction mechanism that controls site‐, regio‐ and stereoselectivity, which
Room Temperature Allenation of Terminal Alkynes with Aldehydes
作者:Junzhe Xiao、Yifan Cui、Can Li、Haibo Xu、Yizhan Zhai、Xue Zhang、Shengming Ma
DOI:10.1002/anie.202109879
日期:2021.12
Au(SIPr)NTf2 has been identified for the roomtemperature ATA reaction to afford diverse 1,3-disubstituted allenes with 1-methyl-1,2,3,4-tetrahydroisoquinoline as amine and aldehyde and TFE or HFIP as the mediator. A formal synthesis of (−)-centrolobine and synthetic transformations have been demonstrated.
Au(SIPr)NTf 2已被确定用于室温 ATA 反应,以提供不同的 1,3-二取代丙二烯,1-甲基-1,2,3,4-四氢异喹啉作为胺和醛,TFE 或 HFIP 作为介体。已经证明了 (-)-centrolobine 和合成转化的正式合成。
Ground-state dioxygen undergoes metal-free [3 + 2]-annulations with allenes and nitrosoarenes under ambient conditions
作者:Jinxian Liu、Manisha Skaria、Pankaj Sharma、Yun-Wei Chiang、Rai-Shung Liu
DOI:10.1039/c7sc01770g
日期:——
heavily on singlet-state 1O2, whereas ground state 3O2 is chemically inactive. Here we report novel [3 + 2]-annulations among ground-state 3O2 (1 bar), allenes, and nitrosoarenes at low temperatures, efficiently yielding dioxygen-containing oxacycles. With less hindered 1-arylallene derivatives, these dioxygen species undergo skeletalrearrangement to 3-hydroxy-1-ketonyl-2-imine oxides. These cycloadditions
具有中性π键基序的分子双氧的环加成反应严重依赖于单重态1 O 2,而基态3 O 2是化学惰性的。在这里,我们报告在低温下基态3 O 2(1 bar),烯和亚硝基芳烃之间的新颖[3 + 2]环,可有效产生含双氧的oxacycles。由于受阻较少的1-芳基丙二烯衍生物,这些双氧物种会发生骨架重排,生成3-羟基-1-酮基-2-亚胺氧化物。这些环加成代表有价值的一锅O,N,O烯的三官能化。我们的EPR实验证实了来自异戊烯/亚硝基芳烃混合物的1,4-双自由基中间体的存在,这表明亚硝基芳烃具有隐藏的双自由基性质。