The reactions of R2SiCH2 (R = Me, Et, or Ph), generated by thermolysis of the corresponding 1,1-disubstituted silacyclobutane at 611°, with a variety of ketones and aldehydes, are described. Two major reaction pathways were observed: olefin formation, postulated to occur via a pseudo Wittig reaction; and silyl enol ether formation. Olefin formation predominated in reactions involving aromatic carbonyls
描述了通过相应的1,1-二取代的硅环丁烷在611°下热解而生成的R 2 Si = CH 2(R = Me,Et或Ph)与各种酮和醛的反应。观察到两个主要的反应途径:烯烃的形成,推测是通过假Wittig反应发生的。与甲硅烷基烯醇醚形成。与涉及以甲硅烷基烯醇醚为主要产物的脂肪族酮的反应相反,在涉及芳族羰基的反应中主要形成烯烃。庚醛反应可得到每种产品可比的产率。
Intermolecular σ‐Bond Cross‐Exchange Reaction between Cyclopropenones and (Benzo)silacyclobutanes: Straightforward Access towards Sila(benzo)cycloheptenones
作者:Wen‐Tao Zhao、Fang Gao、Dongbing Zhao
DOI:10.1002/anie.201803156
日期:2018.5.22
exchange reaction between the C−C bond of cyclopropenones and C−Si bond of (benzo)silacyclobutanes and it proceeds smoothly by treatment with either 1 mol % of a palladium or 2 mol % of a nickel catalyst. This reaction constitutes an unprecedented route for the synthesis of various sila(benzo)suberones. And it is also the first example of a σ‐bond exchange reaction involving cyclopropenones.
Palladium-Catalyzed (4 + 4) Annulation of Silacyclobutanes and 2-Iodobiarenes to Eight-Membered Silacycles via C–H and C–Si Bond Activation
作者:Ming-Hui Zhu、Xiao-Wen Zhang、Muhammad Usman、Hengjiang Cong、Wen-Bo Liu
DOI:10.1021/acscatal.1c00975
日期:2021.5.7
eight-membered silacycles via Pd-catalyzed (4 + 4) annulation of silacyclobutanes and 2-iodobiphenyl derivatives is described. This strategy involves direct C–H and C–Si bond activation followed by a ring annulation and features low catalyst loading, ligand-free conditions, and readily available starting materials. Mechanistic studies revealed the involvement of five-membered palladacycle species in the
Described herein, the chemo- and regio-selective ring expansion of silacyclobutanes to sila-8-membered ringfused biaryl skeletons, enabled by Pd-catalytic conditions. This strategy involves C−C bond cleavage or C(sp2/sp3)−H bond activation and C−Si bond cleavage followed by a double reductive elimination process. DFT calculations indicate that the C−H bond activation or C−C bond cleavage to form palladacycle
benzocyclobutenone and silacyclobutane to merge them into an eight-membered ring skeleton. The present reaction provides a unique example of an intermolecular cross metathesis-type reaction between covalent σ-bonds of low polarity.