13835-81-9Relevant academic research and scientific papers
Asymmetric Synthesis of Silicon-Stereogenic Silanes by Copper-Catalyzed Desymmetrizing Protoboration of Vinylsilanes
Li, Yanfei,Wang, Ying,Xiong, Tao,Zhang, Ge,Zhang, Qian
supporting information, p. 11927 - 11931 (2020/05/22)
The catalytic asymmetric creation of silanes with silicon stereocenters is a long-sought but underdeveloped topic, and only a handful of examples have been reported. Moreover, the construction of chiral silanes containing (more than) two stereocenters is a more arduous task and remains unexploited. We herein report an unprecedented copper-catalyzed desymmetrizing protoboration of divinyl-substituted silanes with bis(pinacolato)diboron (B2pin2). This method enables the facile preparation of an array of enantiomerically enriched boronate-substituted organosilanes bearing contiguous silicon and carbon stereocenters with exclusive regioselectivity and generally excellent diastereo- and enantioselectivity.
On the mechanism of the reductive metallation of asymmetrically substituted silyl chlorides
Oestreich, Martin,Auer, Gertrud,Keller, Manfred
, p. 184 - 195 (2007/10/03)
An investigation of the stereochemical course of the reductive metallation of silyl chlorides with silicon-centred chirality has revealed two major events which are detrimental to stereoselection during silyl anion formation: (1) chloride-induced racemisation of silyl chlorides and (2) nonstereoselective formal dimerisation during metallation providing the corresponding disilane. In control experiments, the stereochemical course of these processes has been independently verified for the reductive metallation of the enantioenriched cyclic silyl chloride (SiS)-7a (R = H, er ≥ 88:12). A screening of several related derivatives of (SiS)-7a led to the sterically encumbered silyl chloride (SiR)-7c (R = iPr, er ≥ 94:6) which displays some unique features. This structural modification prevents racemisation by lithium chloride (T -40 °C) as well as dimerisation (T -100 °C) thus allowing for the first generation of an asymmetrically substituted silyl anion (SiS)-8c (er = 74:26) by reductive metallation of a silyl chloride with silicon-centred chirality. Moreover, the enantiospecificity of the preparation of (SiA)-7c by chlorination [(SiS)-9c → (SiR)-7c] and its reduction with aluminium hydrides [(SiR)-7c → (SiR)-9c] have been unambiguously determined by X-ray crystallography as retention (≥99%) and inversion (≥99%), respectively. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).
Nickel-catalyzed cross-couplings of organosilicon reagents with unactivated secondary alkyl bromides
Powell, David A.,Fu, Gregory C.
, p. 7788 - 7789 (2007/10/03)
A metal-catalyzed cross-coupling of organosilicon compounds with alkyl halides has been developed. Noteworthy attributes of the method are its scope (secondary electrophiles), its high functional-group compatibility, and the air stability of the catalyst components. Copyright
Cross-coupling of triallyl(aryl)silanes with aryl bromides and chlorides: An alternative convenient biaryl synthesis
Sahoo, Akhila K.,Oda, Takuro,Nakao, Yoshiaki,Hiyama, Tamejiro
, p. 1715 - 1727 (2007/10/03)
Cross-coupling of a diverse range of aryl bromides with triallyl(aryl)silanes is effective in the presence of PdCl2/PCy 3 and tetrabutylammonium fluoride (TBAF) in DMSO-H2O to give various biaryls in good yields. It is worthwhile to note that the all-carbon-substituted arylsilanes, stable towards moisture, acid, and base and easily accessible, serve as a highly practical alternative to their aryl(halo)silane counterparts. A catalyst system consisting of [η3-C3H5)PdCl]2 and 2-[2,4,6-(i-Pr)3C6Ha]-C6H4PCy 2 and use of TBAF· 3 H2O in THF-H2O are effective especially for the cross-coupling with aryl chlorides. Both of the catalyst systems tolerate a broad spectrum of common functional groups. The high efficiency of reactions is presumably due to the ready cleavage of the allyl groups upon treatment with TBAF·3 H2O and an appropriate amount of water. Diallyl(diphenyl)silane also cross-couples with various aryl bromides and chlorides in good yields, whereas allyl(triphenyl)silane gives the cross-coupled products in only moderate yields. Through sequential cross-coupling of bromochlorobenzenes with different arylsilanes, a range of unsymmetrical terphenyls are accessible in good overall yields.
