“Diazo” not needed: The title reaction results in the rearrangement of oxonium ylides, which were prepared from readily available homopropargylic allylic ethers instead of diazo compounds, through two different mechanisms: a concerted 2,3‐sigmatropic rearrangement, or a stepwise 1,4‐allyl migration followed by a Claisen rearrangement (see scheme).
Highly Active Palladium Catalyst for the Sonogashira Coupling Reaction of Unreactive Aryl Chlorides
作者:Dong-Hwan Lee、Young-Jun Kwon、Myung-Jong Jin
DOI:10.1002/adsc.201100747
日期:2011.11
communication reports on the β-diketiminatophosphane palladium-catalyzed copper-free Sonogashira coupling of arylchlorides with alkynes. A catalyst loading of 0.5 mol% is sufficient to achieve high performance under relatively mild reaction conditions. Furthermore, dialkynylbenzenes are efficiently prepared by one-pot double Sonogashira couplings of aryl dichlorides.
Intermolecular vinylsilylation of the alkynes 1b–c, having an alkoxy group at the homopropargylic position, with the vinylsilane 2 proceeded in the presence of AlBr3 to give the corresponding dienylsilanes 3b–c in moderate to good yields. In contrast, no product was obtained in the reaction of 1-octyne. The AlBr3 mediated vinylsilylation of the phenylacetylene 9c, bearing methoxy group at the ortho position, also proceeded in good yield.
[(NHC)Ni
<sup>II</sup>
H]‐Catalyzed Cross‐Hydroalkenylation of Cyclopropenes with Alkynes: Cyclopentadiene Synthesis by [(NHC)Ni
<sup>II</sup>
]‐Assisted C−C Rearrangement
作者:Jian‐Qiang Huang、Chun‐Yu Ho
DOI:10.1002/anie.201901255
日期:2019.4.16
achieved for the first time by using new [(NHC)Ni(allyl)]BArF catalysts (NHC=N‐heterocyclic carbenes). By controlling the (NHC)NiIIH relative insertion reactivity with cyclopropene and alkyne, a broad scope of cyclopentadienes was obtained with highly selectively. The structural features of the new (NHC)NiII catalyst were important for the success of the reaction. The mild reaction conditions employed may
通过使用新的[(NHC)Ni(烯丙基)] BAr F催化剂(NHC = N杂环卡宾),首次使用环丙烯和炔烃作为底物对实现了交叉氢烯基化/重排级联反应(HARC )。通过控制(NHC)Ni II H与环丙烯和炔烃的相对插入反应性,可以高度选择性地获得宽范围的环戊二烯。新型(NHC)Ni II催化剂的结构特征对于反应成功至关重要。所采用的温和反应条件可以作为探索(NHC)Ni II辅助的乙烯基环丙烷重排反应性的入口。
Propargyl Alcohols as β-Oxocarbenoid Precursors for the Ruthenium-Catalyzed Cyclopropanation of Unactivated Olefins by Redox Isomerization
作者:Barry M. Trost、Alexander Breder、B. Michael O’Keefe、Meera Rao、Adam W. Franz
DOI:10.1021/ja200971v
日期:2011.4.6
An atom-economical method for the direct synthesis of [3.1.0]- and [4.1.0]-bicyclic frameworks via Ru-catalyzed redoxbicycloisomerization of enynols is reported. The presented results highlight the unique reactivity profile of propargyl alcohols, which function as β-oxocarbene precursors, in the presence of a ruthenium(II) complex. Furthermore, a rare case of a formal vinylic C-H insertion reaction
报道了一种通过 Ru 催化的烯醇氧化还原双环异构化直接合成 [3.1.0]-和 [4.1.0]-双环骨架的原子经济方法。所呈现的结果突出了炔丙醇在钌 (II) 络合物存在下充当 β-氧代卡宾前体的独特反应性特征。此外,还描述了一种罕见的正式乙烯基 CH 插入反应的情况。