在内部基因的分子间水化中,基控制的显著区域和立体分歧:实验和理论研究
Shengtao Ding1, Li-Juan Song, Lung Wa Chung
1Department of Chemistry, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong SAR, China.
Journal of the American Chemical Society
|August 27, 2013
概括
催化剂可实现基因的联体控制的水化,产生各种维尼尔迪西兰. 在这种高效的合成方法中,体和催化剂配体决定了相反的区域和立体选择性.
科学领域:
- 有机金属化学 有机金属化学
- 催化剂是一种催化剂.
- 合成有机化学 合成有机化学
背景情况:
- 内部基的分子间水化是关键的合成转化.
- 在这些反应中实现高区域和立体选择性仍然是一个挑战.
- 干设计是控制催化结果的关键.
研究的目的:
- 揭示第一个高效的联体受控区域和立体分离的内部基因的分子间水化.
- 探索阴阳复合物的催化活性,特别是[Cp*Ru(MeCN) 3) +和[CpRu(MeCN) 3) +.
- 研究基和催化剂连接体在控制选择性的作用.
主要方法:
- 使用阴阳复合物的催化 ([Cp*Ru(MeCN) 3+和[CpRu(MeCN) 3+).
- 基基因的分子间水化.
- 密度函数理论 (DFT) 计算以阐明反应机制.
- 理论预测的实验验证.
主要成果:
- 发现了内部基因的联体受控,区域和立体分离的分子间水化.
- 形成具有优良和相反的区域和立体选择性 (α抗与β合成添加) 的乙烯基迪西兰,取决于催化剂配体 (Cp*与Cp).
- 证明基掩盖组为选择性提供了硬质散体,并使多功能产品衍生成为可能.
- DFT计算揭示了一种涉及氧化水合金化,异构化和还原性丝迁移的机制.
结论:
- 连接体和基替代物的固体效应对区域和立体选择性产生了关键的影响.
- 基和催化剂连接体上的基组之间的相互作用决定了观察到的立体差异.
- 这项工作提供了一个多功能平台,可以通过受控的水化合成有价值的构件.
相关概念视频
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
Introduction
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
02:40Alkynes to Aldehydes and Ketones: Acid-Catalyzed Hydration
Introduction
Analogous to alkenes, alkynes also undergo acid-catalyzed hydration. While the addition of water to an alkene gives an alcohol, hydration of alkynes produces different products such as aldehydes and ketones.
Analogous to alkenes, alkynes also undergo acid-catalyzed hydration. While the addition of water to an alkene gives an alcohol, hydration of alkynes produces different products such as aldehydes and ketones.
02:36Regioselectivity and Stereochemistry of Hydroboration
A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
02:34Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.
02:17Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
If a set of reactants can yield multiple constitutional isomers, but one of the isomers is obtained as the major product, the reaction is said to be regioselective. In such reactions, bond formation or breaking is favored at one reaction site over others.
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...