136551-57-0Relevant articles and documents
Isotope effects and the mechanism of chlorotrimethylsilane-mediated addition of cuprates to enones
Frantz, Doug E.,Singleton, Daniel A.
, p. 3288 - 3295 (2007/10/03)
Kinetic isotope effects were determined for the chlorotrimethylsilane- mediated reactions of cyclohexenone with lithium dibutylcuprate in tetrahydrofuran and with lithium butyl(tert-butylethynyl)cuprate in ether. For the reaction in tetrahydrofuran, the observation of a significant carbonyl oxygen isotope effect (16k/17k = 1.018-1.019) and small olefinic carbon isotope effects (12k/13k = 1.003-1.008) is consistent with rate- limiting silylation of an intermediate π-complex. Theoretically predicted isotope effects for model reactions support this conclusion. Rate-limiting silylation is also supported by relative reactivity studies of chlorotrimethylsilane versus chlorodimethylphenylsilane. The absence of a significant butyl-group carbon isotope effect on product formation indicates that the cuprate butyl groups are nonequivalent in the intermediate leading to the product-determining step. In diethyl ether the isotope effects revert to values similar to those found previously in reactions of cyclohexenone with lithium dibutylcuprate in the absence of chlorotrimethylsilane, consistent with no change in the overall mechanism in this solvent. A mechanistic hypothesis for the differing effects of TMSCl with changes in solvent and substrate is presented.
PHOTOCLEAVAGE OF CARBON-TIN BOND ACTIVATED BY NEIGHBORING
Sato, Tadashi,Takezoe, Kohji
, p. 4003 - 4006 (2007/10/02)
β-Stannyl ketones underwent various types of reaction upon UV-irradiation, depending upon the substitution pattern of the substrate, and upon the solvent used.
Lewis Acid Mediated Reactions of Organocopper Reagents. Entrainment in the Conjugate Addition to α,β-Unsaturated Ketones, Esters, and Acids via the RCu*BF3 System
Yamamoto, Yoshinori,Yamamoto, Sinichi,Yatagai, Hidetaka,Ishihara, Yuji,Maruyama, Kazuhiro
, p. 119 - 126 (2007/10/02)
Lewis acid mediated reactions of organocopper reagents with various kinds of α,β-unsaturated carbonyl derivatives are described.RCu*BF3, as well as RCu-other Lewis acid systems, is useful for the conjugate addition to the α,β-unsaturated ketones and esters, whose double bonds are sterically crowded.Certain α,β-unsaturated carboxylic acids also undergo a 1,4-addition through this reagent.Methyl sorbate undergos a 1,4-addition via BuCu*BF3, while undergoing a 1,6-α,δ-addition via Bu2CuLi.BuCu*BF3 reacts more readily with an aldehyde than with a ketone; the degree of chemoselectivity is greater than that of Bu2CuLi, BuLi, or BuMgBr.The R2CuLi-BF3 system is useful for the double alkylation of α,β-unsaturated esters at the β-position and the carbonyl center.Stereochemical aspects of these new copper reagents are also reported.