M=N(alpha) 循环添加和N(alpha) -N(beta) 插入化化合物与基因的反应:一项综合实验和计算研究
A Daniel Schofield1, Ainara Nova, Jonathan D Selby
1Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, UK.
Journal of the American Chemical Society
|July 13, 2010
概括
这项研究揭示了水化物与酸盐的新型反应,形成阿扎蒂坦或维尼尔伊米多化合物. 这些反应涉及循环添加和N-N键插入,其机制受到替代物的电子作用的影响.
科学领域:
- 有机金属化学 有机金属化学
- 化学 的化学
- 合成有机化学 合成有机化学
背景情况:
- 化是有机金属化学中的多功能联结体.
- 了解它们与类等不和化合物的反应性对于开发新的合成方法至关重要.
研究的目的:
- 为了研究二胺胺胺基支化的反应与终端和内部的基基.
- 阐明反应机制,包括循环添加和N-N键插入路径.
- 探索替代物的电子效应对反应结果和区域化学的影响.
主要方法:
- 结合实验研究和密度函数理论 (DFT) 计算.
- 在不同的温度条件下,化化合物的复合物与各种基基的反应.
- 使用光谱技术和X射线晶体学 (隐含) 分析反应产物.
- 动力学研究,包括激活参数的确定 (ΔH‡, ΔS‡, ΔG‡) 和哈梅特分析.
主要成果:
- 在室温下通过 [2+2] 循环添加基到Ti=N(α) 键的形式形成阿扎蒂坦环丁.
- 在高温下或与不同的复合物通过净插入到N(α) -N(β) 键中,形成乙烯基模态化合物.
- 机械洞察力揭示N-N键插入通过基环添加,然后通过分子内N (α) 原子迁移进行.
- 证明吸收电子的基团稳定中介物和直接区域化学,而释放电子的基团则有利于N(α) 迁移阶段.
结论:
- 该研究提供了第一个金属化物反应的例子,涉及基环添加和N-N键插入.
- 反应机制复杂,涉及初始循环添加和随后的分子内重新排列.
- 替代剂对基因的影响在确定反应途径和产品分布方面起着至关重要的作用.
相关概念视频
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.
Alkynes 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.
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.
Conjugate Addition to α,β-Unsaturated Carbonyl Compounds
α,β-Unsaturated carbonyl compounds are molecules bearing a carbonyl and alkene functionality in conjugation with each other. The conjugation in the molecule leads to three resonance structures. The hybrid form exhibits two probable electrophilic sites: the carbonyl carbon and the β carbon.
Electrophilic Addition to Alkynes: Halogenation
Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Cycloaddition Reactions: MO Requirements for Thermal Activation
Thermal cycloadditions are reactions where the source of activation energy needed to initiate the reaction is provided in the form of heat. A typical example of a thermally-allowed cycloaddition is the Diels–Alder reaction, which is a [4 + 2] cycloaddition. In contrast, a [2 + 2] cycloaddition is thermally forbidden.


