使用催化剂的C(sp3) -F键的碳-碳合
Weixing Gu1, Mason R Haneline, Christos Douvris
1Department of Chemistry, Texas A&M University, College Station, Texas 77842, USA.
Journal of the American Chemical Society
|September 3, 2009
概括
新的催化剂使用基化合物使基化C-F键的基化脱成为可能. 这种选择性反应将C-F债券转换为高保证率的C-Me债券.
科学领域:
- 有机金属化学 有机金属化学
- 化学 的化学
- 催化剂是一种催化剂.
背景情况:
- 阿里法式C-F债券通常没有反应.
- 现有的C-F债券功能化的方法往往缺乏选择性或需要苛刻的条件.
研究的目的:
- 开发高效和选择性的催化剂,用于化异形C-F键.
- 为了研究这种新型基化除 (AlkDF) 反应的机制和范围.
主要方法:
- 采用基酸等价物与六博酸离子作为催化剂.
- 使用各种基化合物,包括三甲基 (Me(3) Al) 和三甲基 (Et(3) Al),作为化剂.
- 使用标准分析技术分析反应产品,以确定转化和选择性.
主要成果:
- 开发了高效且寿命长的催化剂,用于C ((sp ((3)) -F键的基化除 (AlkDF).
- 证明C-F债券的高保证性转换为C-Me债券使用Me(3) Al.
- 观察到,只有C(sp(3)) -F债券是反应性的,而C(sp(2)) -F债券没有受到影响.
- 确定了化化作为与Et(3) Al竞争的途径,表明有竞争性的化物与基转移.
- 展示了有机化合物的耐水能力,简化了反应条件.
结论:
- 基催化剂提供了一种选择性和高效的方法,用于基化C-F键的基化脱.
- 这种催化系统比未催化C-F激活提供了优势,包括更高的速率和选择性.
- 该方法适用于含有异形C-F键的各种基质,包括单醇和CF(3) 组.
相关概念视频
Reduction 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.
Reduction of Alkenes: Catalytic Hydrogenation
Alkenes undergo reduction by the addition of molecular hydrogen to give alkanes. Because the process generally occurs in the presence of a transition-metal catalyst, the reaction is called catalytic hydrogenation.
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the surface of...
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the surface of...
Alkenes via Reductive Coupling of Aldehydes or Ketones: McMurry Reaction
The radical dimerization of ketones or aldehydes gives vicinal diols through a pinacol coupling reaction. However, the behavior of titanium metals used for the reaction as a source of electrons is unusual. When the reaction is carried out in the presence of titanium, diols can be isolated at low temperatures. Else titanium further reacts with diols, forming alkenes through the McMurry reaction.
Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.
¹H NMR: Long-Range Coupling
The coupling interactions of nuclei across four or more bonds are usually weak, with J values less than 1 Hz. While these are usually not observed in spectra, the presence of multiple bonds along the coupling pathway can result in observable long-range coupling.
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene π orbitals.
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene π orbitals.
Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...


