Synthesis of Silacyclohexanones from Divinylsilanes and Allylamines by a Rh-Catalyzed Cyclization
作者:Jiawei Guo、Song Liu、Qinjiao Pang、Hongyun Zhang、Lu Gao、Li Chen、Zhenlei Song
DOI:10.1021/acs.orglett.1c04183
日期:2022.1.21
An efficient synthesis of silacyclohexanones bearing a variety of silyl substituents has been developed by a [Rh(coe)2Cl]2/PCy3-catalyzed cyclization of divinylsilanes with Jun’s allylamine. The silacyclohexanones can be oxidized with DDQ to give the corresponding silacyclohexadienones, which are further transformed into silicon analog of 2-deoxystreptamine or exo-alkylidenesilacyclohexadienes.
We have synthesized and separated the enantiomer pair of chiral cyclotrisiloxanes for the first time. Three-blade propeller-like alignment of three phenyl groups in tri(2-butyl)triphenylcyclotrisiloxane induced a positive Cotton effect with (R)-2-butyl group, and a negative effect with (S)-2-butyl substituent.
Nickel‐Catalyzed Reductive C(sp
<sup>2</sup>
)−Si Coupling of Chlorohydrosilanes via Si−Cl Cleavage
作者:Zhen‐Zhen Zhao、Xiaobo Pang、Xiao‐Xue Wei、Xue‐Yuan Liu、Xing‐Zhong Shu
DOI:10.1002/anie.202200215
日期:2022.5.16
C−Si bond-forming reaction between R−X and Cl−Si(H)R2 was achieved using reductive nickel catalysis. This method offers access to structurally diverse aryl- and alkenylhydrosilanes from phenol and ketonederivatives. The reaction can be conducted on gram scale and allows for incorporating a hydrosilane moiety into biologically active molecules.
The enantioselective construction of silicon-stereocenter by asymmetric enamine catalysis is reported. The reaction proceeds via an unprecedented desymmetric intramolecular aldolization of prochiral siladials for the diverse synthesis of multifunctional silicon-stereogenic silacycles.
The transient absorption of radical cations of a variety of substituted polysilanes is discussed quantitatively in terms of the molar extinction coefficient and oscillator strength by nanosecond pulse radiolysis. Oxygen -saturated polysilane solutions in benzene exhibit a strong transient absorption band ascribed to the polysilane radical cation. The transient species react with N,N,N,N-tetramethyl-p-phenylenediamine (TMPD) to produce TMPD radical cations. On the basis of the molar extinction coefficient of the TMPD radical cation, the molar extinction coefficients for the radical cations of polysilanes are found to increase in the range 3.3 x 10(4) to 2.0 x 10(5) M(-1) cm(-1) with increasing polymer segment length. The stepwise increase in the total oscillator strength with an increase in the number of phenyl rings directly bonded to the Si skeleton suggests the delocalization of the positive polaron state and/or the SOMO state over the phenyl rings, indicating the importance of phenyl rings in intermolecular hole transfer processes.