- Catalytic Enantioselective Dehydrogenative Si-O Coupling to Access Chiroptical Silicon-Stereogenic Siloxanes and Alkoxysilanes
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A rhodium-catalyzed enantioselective construction of triorgano-substituted silicon-stereogenic siloxanes and alkoxysilanes is developed. This process undergoes a direct intermolecular dehydrogenative Si-O coupling between dihydrosilanes with silanols or alocohols, giving access to a variety of highly functionalized chiral siloxanes and alkoxysilanes in decent yields with excellent stereocontrol, that significantly expand the chemical space of the silicon-centered chiral molecules. Further utility of this process was illustrated by the construction of CPL-active (circularly polarized luminescence) silicon-stereogenic alkoxysilane small organic molecules. Optically pure bis-alkoxysilane containing two silicon-stereogenic centers and three pyrene groups displayed a remarkable glum value with a high fluorescence quantum efficiency (glum = 0.011, φF = 0.55), which could have great potential application prospects in chiral organic optoelectronic materials.
- Zhu, Jiefeng,Chen, Shuyou,He, Chuan
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- Selective Electrochemical Hydrolysis of Hydrosilanes to Silanols via Anodically Generated Silyl Cations
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The first electrochemical hydrolysis of hydrosilanes to silanols under mild and neutral reaction conditions is reported. The practical protocol employs commercially available and cheap NHPI as a hydrogen-atom transfer (HAT) mediator and operates at room temperature with high selectivity, leading to various valuable silanols in moderate to good yields. Notably, this electrochemical method exhibits a broad substrate scope and high functional-group compatibility, and it is applicable to late-stage functionalization of complex molecules. Preliminary mechanistic studies suggest that the reaction appears to proceed through a nucleophilic substitution reaction of an electrogenerated silyl cation with H2O.
- Liang, Hao,Wang, Lu-Jun,Ji, Yun-Xing,Wang, Han,Zhang, Bo
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supporting information
p. 1839 - 1844
(2020/12/01)
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- Metal-free hydrogen evolution cross-coupling enabled by synergistic photoredox and polarity reversal catalysis
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A synergistic combination of photoredox and polarity reversal catalysis enabled a hydrogen evolution cross-coupling of silanes with H2O, alcohols, phenols, and silanols, which afforded the corresponding silanols, monosilyl ethers, and disilyl ethers, respectively, in moderate to excellent yields. The dehydrogenative cross-coupling of Si-H and O-H proceeded smoothly with broad substrate scope and good functional group compatibility in the presence of only an organophotocatalyst 4-CzIPN and a thiol HAT catalyst, without the requirement of any metals, external oxidants and proton reductants, which is distinct from the previously reported photocatalytic hydrogen evolution cross-coupling reactions where a proton reduction cocatalyst such as a cobalt complex is generally required. Mechanistically, a silyl cation intermediate is generated to facilitate the cross-coupling reaction, which therefore represents an unprecedented approach for the generation of silyl cationviavisible-light photoredox catalysis.
- Cao, Jilei,Lu, Kanghui,Ma, Lishuang,Yang, Xiaona,Zhou, Rong
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supporting information
p. 8988 - 8994
(2021/11/23)
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- Selective Manganese-Catalyzed Oxidation of Hydrosilanes to Silanols under Neutral Reaction Conditions
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The first manganese-catalyzed oxidation of organosilanes to silanols with H2O2 under neutral reaction conditions has been accomplished. A variety of organosilanes with alkyl, aryl, alknyl, and heterocyclic substituents were tolerated, as well as sterically hindered organosilanes. The oxidation appears to proceed by a concerted process involving a manganese hydroperoxide species. Featuring mild reaction conditions, fast oxidation, and no waste byproducts, the protocol allows a low-cost, eco-benign synthesis of both silanols and silanediols.
- Wang, Kaikai,Zhou, Jimei,Jiang, Yuting,Zhang, Miaomiao,Wang, Chao,Xue, Dong,Tang, Weijun,Sun, Huamin,Xiao, Jianliang,Li, Chaoqun
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supporting information
p. 6380 - 6384
(2019/05/06)
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- Heme Protein Catalysts for Carbon-Silicon Bond Formation In Vitro and In Vivo
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The present invention provides compositions and methods for catalyzing the formation of carbon-silicon bonds using heme proteins. In certain aspects, the present invention provides heme proteins, including variants and fragments thereof, that are capable of carrying out in vitro and in vivo carbene insertion reactions for the formation of carbon-silicon bonds. In other aspects, the present invention provides methods for producing an organosilicon product, the method comprising providing a silicon-containing reagent, a carbene precursor, and a heme protein; and combining the components under conditions sufficient to produce an organosilicon product. Host cells expressing the heme proteins are also provided by the present invention.
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Paragraph 0243; 0244
(2017/08/26)
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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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- Peculiarities in the cleavage by methyllithium of unsymmetrical disilanes
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The title reactions did not produce the more stable silyl anions from the disilanes studied, they either occurred by attack at the more electrophilic silicon atom, or led to unexpected products.
- Hevesi,Dehon
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p. 8031 - 8032
(2007/10/02)
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- Dimethylsilyl-substituted benzoyl chlorides and a process for preparing the same
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The invention relates to dimethylsilyl-substituted benzoyl chlorides and a process for preparing the same, which comprises reacting a dihaloaromatic compound with dimethylchlorosilane and magnesium by the Grignard method to form halophenyldimethylsilanes,
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