铜(I)催化的甲硅烷基硼酸酯与α,β-不饱和醛,酮和酯的共轭加成反应是合成上公认的反应。首次分离并使用了中心反应性中间体以及烯醇硼作为主要反应产物,以便在实验基础上推导催化循环。使用NHC Cu I络合物作为模型催化剂,可以进行有效的催化转化以及分离和表征形成的烯醇铜络合物作为关键中间体。结果表明,对于该催化体系,该烯酸酯的性质-O-或C-烯酸酯-对于催化过程至关重要。对于α,β-不饱和醛和酮,O主要形成β-烯酸酯,而对于α,β-不饱和酯,C-烯酸酯是主要产物。催化转换仅适用于O-烯醇铜,因为它们在催化活性的Cu-Si物种和热力学上受青睐的硼酸酯的(重新)形成下与甲硅烷基硼酸酯有效反应。因此,C-烯醇铜的形成抑制了催化过程,并且仅在通过醇添加剂进行溶剂分解之后才可能进行有效的转换。通过执行由原位NMR光谱监测的逐步化学计量反应,可以追溯各个催化过程。
[(18-C-6)K][(N≡C)Cu<sup>I</sup>–SiMe<sub>2</sub>Ph], a Potassium Silylcyanocuprate as a Catalyst Model for Silylation Reactions with Silylboranes: Syntheses, Structures, and Catalytic Properties
作者:Jacqueline Plotzitzka、Christian Kleeberg
DOI:10.1021/acs.inorgchem.7b00749
日期:2017.6.5
extension allows the efficient silylation of ketones. In addition, a number of peculiarities of the catalytic reaction are readily rationalized on the basis of the mechanistic insight already established using [(NHC)Cu–SiMe2Ph] as a model catalyst. Analogously to the NHC model system, the reaction of 2 with the silylborane 1 furnishes the silylcyanocuprate [(18-C-6)K][NC–Cu–SiMe2Ph] (3) as a potential crucial
Cu I催化的甲硅烷基硼烷(特别是pinB–SiMe 2 Ph(1))作为甲硅烷基来源的甲硅烷基化反应最近受到了广泛的关注。CuCN / NaOMe是最有效,用途最多且最简单的催化剂体系之一。然而,对于催化相关的物种一无所知。使用基于NHC的模型催化剂,已确定类型[(NHC)Cu-SiMe 2 Ph]的铜甲硅烷基络合物是这些催化过程中的关键物种。定义明确且具有光谱学和结构特征的复合物[(18-C-6)K] [NC–Cu–O t Bu](2),作为催化系统的模型,CuCN / NaOMe对既定的示例性底物(醛,亚胺,α,β-不饱和羰基)表现出可比的催化活性,并且可以使酮有效地甲硅烷基化。另外,基于已经使用[(NHC)Cu-SiMe 2 Ph]作为模型催化剂建立的机理洞察力,很容易合理化催化反应的许多特殊性。与NHC模型系统类似,2与甲硅烷基硼烷1的反应提供了甲硅烷基氰基丙酸酯[(18-C-6)K]
Enantioselective Conjugate Silyl Additions to α,β-Unsaturated Aldehydes Catalyzed by Combination of Transition Metal and Chiral Amine Catalysts
We report that transition metal-catalyzed nucleophilic activation can be combined with chiral amine-catalyzed iminium activation as exemplified by the unprecedented enantioselectiveconjugateaddition of a dimethylsilanyl group to α,β-unsaturatedaldehydes. These reactions proceed with excellent 1,4-selectivity to afford the corresponding β-silyl aldehyde products 3 in high yields and up to 97:3 er
Copper-Catalyzed Conjugate Addition of a Bis(triorganosilyl) Zinc and a Methyl(triorganosilyl) Magnesium
作者:Martin Oestreich、Barbara Weiner
DOI:10.1055/s-2004-831331
日期:——
A practical copper-catalyzed conjugate silylation of α,β-unsaturated carbonyl compounds 4 utilizing bis(triorganosilyl) zinc reagent 3 is described. Moreover, mixed methyl(triorganosilyl) magnesium 7 also transfers its silyl ligand to simple enones 4 under copper catalysis.
Conjugate Additions of a Simple Monosilylcopper Reagent with Use of the CuI·DMS Complex: Stereoselectivities and a Dramatic Impact by DMS
作者:Jesse Dambacher、Mikael Bergdahl
DOI:10.1021/jo048269e
日期:2005.1.1
reagent with DMS as the solvent is very useful with stericallyhindered (β,β-disubstituted) enones, and provides very high yields of the β-silylated 1,4-addition products. Since there is no oligomerization problem associated with the simple monosilylcuprate reagent, this reagent should be considered as a very useful 1,4-silyl donor to enals, enones, and enoates in conjugate addition reactions.
Employing the simple monosilylcopper reagent, Li[PhMe<sub>2</sub>SiCuI], in 1,4-addition reactions
作者:Jesse Dambacher、Mikael Bergdahl
DOI:10.1039/b210792a
日期:——
Conjugate addition reactions using the simple Li[PhMe2SiCuI] reagent to a variety of α,β-unsaturated carbonyl compounds is described; dimethyl sulfide from the purification of CuI plays a key role for very high yields as well as high stereoselectivities in the formation of β-silyl carbonyl compounds.