通过alkyne循环异构化合成固态拥挤的双烯
Junichiro Hirano1, Sayaka Miyoshi1, Eiji Yashima1
1Department of Molecular and Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603, Japan. fukui@chembio.nagoya-u.ac.jp.
选择性地在拥挤的地区发生了四位置换的基[g,p]烯的大量基环化. 这导致了扭曲的双基因,由于硬质障碍,它对种族化有很高的障碍.
科学领域:
- 有机化学 有机化学
- 超分子化学 超分子化学
- 材料科学 材料科学 材料科学
背景情况:
- 基[g,p]烯衍生物因其独特的光物理和电子特性而受到探索.
- 固态阻碍在指导区域选择性和影响复杂有机合成中的分子架构方面发挥着至关重要的作用.
- 基因,由于其固有的性和潜在的应用,在分子科学中具有显著的兴趣.
研究的目的:
- 在一个硬质要求高的四置换基[g,p]烯支架上研究基环化聚合物的区域选择性.
- 为了合成和表征一种新型的双基结构,从这种循环异构化中衍生出来.
- 评估大型替代剂对所产生的烯的立体化学特性,特别是种族化屏障的影响.
主要方法:
- 合成2,7,10,15-tetra(ortho-alkynylphenyl) benzo[g,p]chrysene与重的4-alkoxy-2,6-dimethylphenyl组的合成. 这是一个非常简单的方法.
- 催化阿尔基因循环异构化反应.
- 使用NMR光谱学和X射线晶体学进行结构性表征.
- 脊镜测量以评估种族化障碍.
主要成果:
- 选择性循环异构发生在化阻碍湾区域的子[g,p]烯核心.
- 成功获得了一种新的,扭曲的双基结构.
- 庞大的外围群体诱导了显著的分子内硬体排斥,导致了高的种族化障碍.
结论:
- 该研究表明,通过硬质效应,通过复杂的基环化聚合物对区域选择性的精确控制.
- 合成的双烯表现出独特的结构扭曲和增强的稳定性对抗种族化.
- 这项工作为在不对称催化或分子电子学中的潜在应用提供了对具有高配置稳定性的奇拉分子设计的见解.
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相关概念视频
Preparation of Alkynes: Dehydrohalogenation
Alkynes can be prepared by dehydrohalogenation of vicinal or geminal dihalides in the presence of a strong base like sodium amide in liquid ammonia. The reaction proceeds with the loss of two equivalents of hydrogen halide (HX) via two successive E2 elimination reactions.
Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
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.
Preparation of Alkynes: Alkylation Reaction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
Electrophilic Addition to Alkynes: Halogenation
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.
Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
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.
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
