以为媒介的机械化学循环脱
Kanna Fujishiro1, Yuta Morinaka2, Yohei Ono2
1Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan.
Journal of the American Chemical Society
|April 3, 2023
概括
研究人员开发了一种新的介导的机械化学离子循环脱. 这种易于使用的方法有效合成多环芳和纳米基,包括最长的非替代分子烯,烯.
科学领域:
- 有机合成
- 材料化学
- 纳米技术
背景情况:
- 循环脱对于合成多环芳 (PAH),异芳化合物和纳米基因至关重要.
- 使用的阳离子循环脱是有效的,但其实用性,热性和可扩展性较差.
- 现有的方法对广泛的合成应用提出了重大挑战.
研究的目的:
- 开发一种新的,实用的,可扩展的离子循环脱方法.
- 为合成PAH和纳米基因建立一个用户友好的协议.
- 合成新的纳米基因,包括最长的非替代分子烯.
主要方法:
- 一种介导的机械化学阴离子循环脱反应的发展.
- 在室温和空气下使用常规线.
- 通过计算和NMR分析调查反应范围,机制和克尺度合成.
主要成果:
- 在30分钟内从1,1'-binaphthyl中实现烯的高效合成,产量为94%.
- 证明了反应的实用性,空气耐受性和室温操作.
- 通过多次循环脱,成功合成了新型纳米基因,包括五烯 ([5]rylene).
结论:
- 中介的机械化学协议在实用性和适用性方面比现有方法具有显著的优势.
- 这种用户友好的方法可以合成复杂的纳米基因,扩大合成能力.
- 这项研究提供了对反应范围,机制和局限性的全面了解,为未来的应用铺平了道路.
相关概念视频
01:17Thermal Electrocyclic Reactions: Stereochemistry
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The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
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01:26Thermal and Photochemical Electrocyclic Reactions: Overview
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Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
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01:26Photochemical Electrocyclic Reactions: Stereochemistry
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The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
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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...
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02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
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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.
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