催化三组分非对称的基与基双联:一个密度功能理论研究研究
Tao Yu1, Jingxuan Zhang1, Guo Liu1
1Faculty of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650092, China.
Molecules (Basel, Switzerland)
|April 13, 2024
概括
这项研究使用密度函数理论来绘制催化反应机制,从和中产生跳过的三烯. 氧化添加步骤控制了选择性,而添加剂则促进了催化剂再生.
科学领域:
- 有机金属化学 有机金属化学
- 催化剂是一种催化剂.
- 计算化学计算化学
背景情况:
- 催化反应对于合成复杂的有机分子至关重要.
- 了解反应机制是优化催化过程和产品选择性的关键.
- 基与基的非对称双合为有价值的跳过三烯结构提供了途径.
研究的目的:
- 阐明催化三组分非对称的基与基二联合反应的详细反应机制.
- 为了确定催化循环中速度决定和选择性控制的步骤.
- 研究添加剂和基质特性在反应效率和产品形成中的作用.
主要方法:
- 密度函数理论 (DFT) 描述被用来分析结构,能量和选择性方面.
- 计算绘制了拟议的催化循环的五个连续步骤:氧化添加,β-F消除,环开复合,C-B裂解和还原性消除.
- 双描述符和相互作用区域指标 (IRI) 分析被用来预测和解释基质选择性.
主要成果:
- 氧化添加 (OA) 和还原消除 (RE) 步骤被确定为反应速率的关键贡献者,OA是选择性决定的步骤 (分别为24.2和24.8kcal·mol-1的自由能量障碍).
- 使用基于希尔什菲尔德电荷的双重描述符,准确预测了基质化学和区域选择性.
- 发现酸和t-BuOK添加剂对于促进反应和再生活性催化剂至关重要.
结论:
- 这项研究成功地解决了催化跳过三烯合成的机制性途径.
- DFT计算为控制选择性和优化反应条件提供了宝贵的见解.
- 这些发现支持使用低催化剂负荷 (5mol%Ni(COD) 2) 的高效跳过三烯形成.
相关概念视频
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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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02:38Electrophilic Addition to Alkynes: Halogenation
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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.
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02:27Preparation of Alkynes: Alkylation Reaction
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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.
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02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
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02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
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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.
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02:37Structure and Physical Properties of Alkynes
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