74970-67-5Relevant academic research and scientific papers
B(C6F5)3 catalyzed hydrosilation of enones and silyl enol ethers
Blackwell, James M,Morrison, Darryl J,Piers, Warren E
, p. 8247 - 8254 (2007/10/03)
The 1,4 hydrosilation of a variety of simple α,β-unsaturated enones as catalyzed by B(C6F5)3 (1-2%) is described. For substrates with no steric hindrance near the β-carbon, 1,4 addition of silane is very clean; in other instances, 1,2 hydrosilation is competitive. The reaction is facile with five commercially available silane reagents. For two examples, a novel hydrosilation of the resulting silylenol ethers was also observed. The net trans stereochemistry of H-Si addition to the silylenol ether C=C bond was established and points to a stepwise mechanism for this reaction. This was supported by the observation and full spectroscopic characterization of a silylcarboxonium ion intermediate with an [HB(C6F5)3]- counteranion in the hydrosilation of the silylenol ether derived from 4,4-dimethyl-2-cyclohexen-1-one and PhMe2SiH.
The application of intramolecular radical cyclizations of acylsilanes in the regiospecific formation of cyclic silyl enol ethers
Huang,Chang,Wang,Tsai
, p. 8983 - 8991 (2007/10/03)
Acylsilanes with terminal α-stannyl bromide or xanthate functionalities are prepared, α-Stannyl radicals generated from these acylsilanes undergo intramolecular cyclizations to give cyclic silyl enol ethers regiospecifically. The radical processes involve radical cyclization, Brook rearrangement, and β-fragmentation in sequence. A tributylstannyl group serves as the radical leaving group. The newly formed σ-bond and π-bond are located between the same two carbon atoms. This approach is limited to the formation of five-membered rings. In another route, ω-bromo-α-phenylsulfonylacylsilanes are synthesized. The radical cyclizations of these α-sulfonylacylsilanes also give cyclic silyl enol ethers. The phenylsulfonyl moiety is the radical leaving group in this system. Furthermore, the newly formed σ-bond and π-bond are located at adjacent positions sharing a single carbon atom. The latter approach is effective for both five- and six-membered ring formation.
The Scope and Limitations of Intramolecular Radical Cyclizations of Acylsilanes with Alkyl, Aryl, and Vinyl Radicals
Chang, Sheng-Yueh,Jiaang, Weir-Torn,Cherng, Chaur-Donp,Tang, Kuo-Hsiang,Huang, Chih-Hao,Tsai, Yeun-Min
, p. 9089 - 9098 (2007/10/03)
5-Exo cyclizations of primary and secondary radicals with acylsilanes successfully give cyclopentyl silyl ethers. The corresponding 6-exo cyclizations are sensitive to changes of the size of silyl groups. Secondary radicals undergo 6-exo cyclizations with
