- Rhodium-catalyzed carbonylative synthesis of silyl-substituted indenones
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A novel and efficient rhodium-catalyzed procedure for the preparation of silyl-substituted indenones has been developed. Using silanes and internal alkynes as the substrates, in the presence of CO, good to excellent yields of the desired indenones were isolated. A wide range of functional groups, encompassing esters, amines, nitriles and halides, is compatible in this system.
- Zhu, Fengxiang,Spannenberg, Anke,Wu, Xiao-Feng
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supporting information
p. 13149 - 13152
(2017/12/26)
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- Cross-coupling reactions of aromatic and heteroaromatic silanolates with aromatic and heteroaromatic halides
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The alkali-metal salts (potassium and sodium) of a large number of aryl- and heteroarylsilanols undergo efficient cross-coupling with a wide range of aromatic bromides and chlorides under mild conditions to form polysubstituted biaryls. The critical feature for the success of these coupling reactions and their considerable scope is the use of bis(tri-tert-butylphosphine)palladium. Under the optimized conditions, electron-rich, electron-poor, and sterically hindered arylsilanolates afford cross-coupling products in good yields. Many functional groups are compatible with the coupling conditions such as esters, ketones, acetals, ethers, silyl ethers, and dimethylamino groups. Two particularly challenging substrates, (2-benzofuranyl)dimethylsilanolate and (2,6-dichlorophenyl)dimethylsilanolate prepared as their sodium salts showed excellent activity in the coupling reactions, in the former case also with aromatic chlorides. General methods for the efficient synthesis of a wide range of aromatic silanols are also described.
- Denmark, Scott E.,Smith, Russell C.,Chang, Wen-Tau T.,Muhuhi, Joseck M.
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scheme or table
p. 3104 - 3118
(2009/08/07)
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- Electrochemical method for the production of organofunctional silanes
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Organofunctional silanes are prepared in high yield by electrochemically reacting a silane bearing a halo or alkoxy group with a hydrocarbon bearing a halo or alkoxy group in an undivided electrolysis cell with no or minimal complexing agent present.
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Page/Page column 3
(2008/06/13)
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- Kinetic Control in the Cleavage of Unsymmetrical Disilanes
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A series of 12 phenyl-substituted arylpentamethyldisilanes 1a-1 have been synthesized in order to examine the regioselectivity of their nucleophilic Si,Si bond cleavage reactions under Still's conditions (MeLi/HMPA/0°C). It has been found that the sensitivity of these reactions to the electronic effects of the substituents in the phenyl ring could be described by the Hammett-type equation log(kA/kB) = 0.4334 + 2.421(Σσ); (correlation coefficient R = 0.983). The kA/kB ratio represents the relative rate of attack at silicon atom A (linked to the aryl ring) or at silicon atom B (away from the aryl ring) of the unsymmetrical disilanes. Thus, the present investigation shows that the earlier belief according to which the nucleophilic cleavage of unsymmetrical disilanes always produces the more stable silyl anionic species (thermodynamic control) should be abandoned, or at least seriously amended: kinetic factors appear to exert a primary influence on the regioselectivity of such reactions. Since the two major kinetic factors (i.e., electrophilic character of and steric hindrance at a given silicon atom) have opposite effects on the orientation of the reaction, it may happen that kinetic and thermodynamic control lead to the same result. For some of the unsymmetrical disilanes studied, the major reaction path was not the Si,Si bond cleavage; instead, Si-aryl bond breaking occurred, producing the corresponding aryl anions.
- Hevesi, Laszlo,Dehon, Michael,Crutzen, Raphael,Lazarescu-Grigore, Adriana
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p. 2011 - 2017
(2007/10/03)
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