109681-49-4Relevant academic research and scientific papers
Reaction of silylketenes with carbanions: Simple preparation of α- silylketones using organocerium reagents
Akai, Shuji,Kitagaki, Shinji,Matsuda, Satoshi,Tsuzuki, Yasunori,Naka, Tadaatsu,Kita, Yasuyuki
, p. 1135 - 1139 (1997)
Preparation of α-silylketones 1 by the reaction of three kinds of silylketenes 3a-c with various organometallic reagents 4 was studied. Although the use of n-BuLi, MeMgBr, Me2CuLi, Et3Al, and Et2Zn resulted in complicated reactions, organocerium reagents 4 (M=CeCl2) added selectively to the carbonyl carbon of 3 to generate enolate anions A, which were treated with aqueous NH4Cl or alkyl halides 5 to give 1. Seventeen α-silylketones 1a-q were prepared in 3199% yields from three components, 3, alkyl- or arylcerium reagents 4, and proton or alkyl halides 5. This method was applied to a regiocontrolled preparation of two isomeric α-silylketones 1r, s.
β-silylcarbenes from isolable diazosilanes
Creary, Xavier,Butchko, Mark A.
, p. 112 - 118 (2007/10/03)
Manganese dioxide oxidation of the hydrazone derivative of tert-butyldimethylsilyl acetophenone gave 2-tert-butyldimethylsilyl-1-phenyldiazoethane (17) an isolable diazocompound. Thermal and Rh(II)-catalyzed decomposition of diazosilane 17 in cyclohexane led to 1-tert-butyldimethylsilyl-1-phenylethylene (19) as the major product. The formation of alkene 19 presumably involves (tertbutyldimethylsilyl)methylphenylcarbene (21), which undergoes preferential 1,2-silyl migration as opposed to 1,2-hydrogen migration. Thermal decomposition of 17 in cyclohexane under oxygen gave substantial amounts of tert-butyldimethylsilyl acetophenone, presumably by reaction of the intermediate carbene with oxygen. Thermal decomposition of 17 in methanol led to alkene 19 and 2-tert-butyldimethylsilyl-1-methoxy-1-phenylethane (22) as major products, along with a significant amount of trans-1-tert-butyldimethylsilyl-2-phenylethylene (20). Kinetic studies indicate that these products are not derived from acid-catalyzed decomposition of the diazocompound 17. Formation of the methyl ether product 22 suggests the involvement of a β-silyl carbocation intermediate, and solvent isotope effect studies indicate that this cation is at least partially derived from protonation of diazocompound 17 by neutral methanol. Photochemical decomposition of 17 in methanol produced the alkene 19 (97%) along with a small amount (2.4%) of the methyl ether 22. Capture of a photochemically generated carbene 21 by methanol is the proposed origin of this minor product. Geometry optimization of trimethylsilylmethylphenylcarbene (8) and carbene 21 at the HF/6-31G* computational level led to a conformation consistent with a hyperconjugative interaction between the vacant p-orbital of these carbenes and the adjacent C-Si bond. Carbenes 8 and 21 are not energy minima at the B3LYP/6-31G* level, where they rearrange to alkenes without barrier via silyl migration. These theoretical findings contrast with the proposed trapping of carbene 21 by methanol and oxygen.
Stereospecific access to trisubstituted enol ethers from vinylsilanes
Barluenga, Jose,Alvarez-Garcia, Lorenzo J.,Romanelli, Gustavo P.,Gonzalez, Jose M.
, p. 6763 - 6766 (2007/10/03)
The reaction of RCH=CHSiMe3 (R: alkyl or aryl) with IPy2BF4/HBF4 and a set of representative alcohols affords the corresponding addition products as a single regio- and stereoisomers in good yield. Subsequent dehydroiodination with DBU furnishes silyl-substituted enol ethers.
THE SILAPINACOL REARRANGEMENT: CONVERSION OF α,β-DIHYDROXYSILANES INTO α-SILYL CARBONYL COMPOUNDS
Cunico, Robert F.
, p. 4269 - 4272 (2007/10/02)
Treatment of α,β-dihydroxysilanes with trifluoroacetic acid in chloroform results in a 1,2-migration of the silyl group to give α-silyl aldehydes and ketones.The t-butyl-dimethylsilyl compounds can be isolated in high yields.
