Taming the Silylium Ion for Low-Temperature Diels-Alder Reactions
作者:Hendrik F. T. Klare、Klaus Bergander、Martin Oestreich
DOI:10.1002/anie.200904520
日期:2009.11.16
trivalent silicon cation stabilized by an electron‐rich transition metal as the “hot” Lewis acidic site catalyzes challenging Diels–Alderreactions at low temperatures with excellent reaction rates and selectivities (see scheme). In addition to the chemical stability of the silyliumion catalyst (in CH2Cl2), the potential of these reactive compounds is also discussed.
Silylium Ion-Catalyzed Challenging Diels–Alder Reactions: The Danger of Hidden Proton Catalysis with Strong Lewis Acids
作者:Ruth K. Schmidt、Kristine Müther、Christian Mück-Lichtenfeld、Stefan Grimme、Martin Oestreich
DOI:10.1021/ja211856m
日期:2012.3.7
Proton-catalyzed Diels-Alderreactions are not well-documented in the literature, and a representative survey employing TfOH is included here. The outcome of these catalyses is compared with our silylium ion-catalyzed Diels-Alderreactions, thereby clearly corroborating that hidden Brønsted acid catalysis is not operating with our Lewis acid. Several simple-looking but challenging Diels-Alderreactions with exceptionally
Strained to the Limit: When a Cyclobutyl Moiety Becomes a Thermodynamic Sink in a Protolytic Ring-Opening of Photogenerated Oxetanes
作者:Roman A. Valiulin、Teresa M. Arisco、Andrei G. Kutateladze
DOI:10.1021/ol101297b
日期:2010.8.6
Strained polycyclic oxetanes generated photochemically from the Diels−Alder adducts of cyclic dienes and enones undergo deep skeletalrearrangements under protolytic ring-opening conditions offering expeditious access to chlorohydrins and other products of unique skeletal topology.
作者:Ruth K. Schmidt、Hendrik F. T. Klare、Roland Fröhlich、Martin Oestreich
DOI:10.1002/chem.201504777
日期:2016.4.4
preparation of a series of planar chiral, ferrocenyl‐substituted hydrosilanes as precursors of ferrocene‐stabilized silicon cations is described. These molecules also feature stereogenicity at the silicon atom. The generation and 29Si NMR spectroscopic characterization of the corresponding silicon cations is reported, and problems arising from interactions of the electron‐deficient silicon atom and adjacent
描述了一系列平面手性二茂铁基取代的氢硅烷作为二茂铁稳定的硅阳离子的前体的制备。这些分子在硅原子上还具有立体性。报告了相应硅阳离子的生成和29 Si NMR光谱表征,以及由于缺电子的硅原子与相邻C(sp 3)-H键或芳族π供体进行了讨论。通过将硅原子上的另一个取代基束缚在二茂铁骨架上,可以解决这些问题。所得到的环状结构还赋予构象刚度和空间位阻,使得通过完全非对映控制设定硅原子上的中心手性。然后在困难的Diels-Alder反应中测试了这些手性Lewis酸催化剂,但没有发现对映体诱导作用。
Highly Selective Diels−Alder Reactions of Dienophiles with 1,3-Cyclohexadiene Mediated by Yb(OTf)<sub>3</sub>·2H<sub>2</sub>O and Ultrahigh Pressures
作者:Aaron C. Kinsman、Michael A. Kerr
DOI:10.1021/ol0065773
日期:2000.11.1
[GRAPHICS]Ultrahigh pressures and catalytic Yb(OTf)(3). 2H(2)O were found to mediate Diets-Alder reactions of various electron-deficient dienophiles with 1,3-cyclohexadiene to produce endo-bicyclo[2.2.2]oct-2-enes in moderate to excellent yield and selectivity. The proposed total synthesis of hapalindole Q based on bicyclo[2.2.2]oct-2-ene construction by Diels-Alder reaction and subsequent olefin cleavage is outlined, Preliminary results demonstrating the viability of this strategy are presented.