指导群控制的水化:阿尔基因的区域选择性功能化
Yuuya Kawasaki1, Youhei Ishikawa, Kazunobu Igawa
1Department of Molecular and Material Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Japan.
Journal of the American Chemical Society
|December 7, 2011
概括
使用二甲基维尼利 (DMVS) 导向组的催化化实现了对不对称的基因的高区域选择性. 这种方法使得能够合成特定的西莱基异构体和多种功能化化合物.
科学领域:
- 有机金属化学 有机金属化学
- 合成有机化学 合成有机化学
- 催化剂是一种催化剂.
背景情况:
- 水化是有机合成中的一个关键反应.
- 在基因水化中控制区域选择性仍然是一个挑战.
- 指导小组可以影响反应结果.
研究的目的:
- 开发一种高度区域选择性的Pt(0) - - 催化非对称基的水化.
- 调查二甲基维尼利 (DMVS) 组作为指导和加速组的作用.
- 探索从不对称的基因中合成复杂基因和功能化化合物.
主要方法:
- (((0) -催化水化反应.
- 使用二甲基维尼利西 (DMVS) 作为对不对称基的指导组.
- 后续的转化反应的结果是silalkenes.
主要成果:
- 在不对称的基因的水化中实现了高的区域选择性.
- 在DMVS集团的指导下,形成了一种单一的silylalkenes区域异构体.
- 观察到DMVS组对选择性水化有加速作用.
- 合成了各种三替代和具有高区域选择性的多氧功能化化合物.
结论:
- DMVS组是Pt(0) -催化基化的有效指导和加速组.
- 这种方法提供了一个区域选择性途径,以获得有价值的基衍生物.
- 能够从简单的基因有效合成复杂的有机分子.
相关概念视频
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.
02:47Alkynes 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.
02:34Regioselectivity 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.
02:36Regioselectivity 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.
02:17Regioselectivity 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...
02:35Electrophilic Addition to Alkynes: Hydrohalogenation
Electrophilic addition of hydrogen halides, HX (X = Cl, Br or I) to alkenes forms alkyl halides as per Markovnikov's rule, where the hydrogen gets added to the less substituted carbon of the double bond. Hydrohalogenation of alkynes takes place in a similar manner, with the first addition of HX forming a vinyl halide and the second giving a geminal dihalide.