帕拉催化形式胺的分子间添加到alkynes
Tetsuaki Fujihara1, Yuko Katafuchi, Tomohiro Iwai
1Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan.
一种新的催化剂能够将形式胺添加到基中,从而产生有价值的不和胺. 这种高效的方法适用于内部和终端基因,提供广泛的基板范围.
科学领域:
- 有机化学 有机化学
- 催化剂是一种催化剂.
- 合成方法论 合成方法论
背景情况:
- 甲胺是有机合成中的多功能构建块.
- 有效的基因功能化的方法对于创建复杂分子至关重要.
- 催化提供了强大的工具,用于碳-异原子键的形成.
研究的目的:
- 开发一种新的催化系统,用于将形式胺添加到基的分子间.
- 为了实现α,β不和胺的区域选择性和立体选择性合成.
- 探索开发的催化系统的范围和局限性.
主要方法:
- 使用一种新型的催化剂系统与酸化物添加剂.
- 研究形式胺与内部和末端基因的反应.
- 分析反应产品的区域选择性和立体选择性.
主要成果:
- 开发的系统有效地催化了形式胺的添加到内部基,产生具有高区域性和立体选择性的 (E) -α,β不和胺.
- 这种方法代表了第一次成功地将形式胺添加到终端基中,产生具有终端甲基部分的α,β不和胺.
- 这种反应对各种功能化基质具有广泛的适用性,并且对N,N-非替代形式胺和norbornene.
结论:
- 已经建立了一种新且高效的催化方法,用于将形式胺添加到基的分子间添加.
- 该方法可获得有价值的α,β不和胺基,对区域和立体化学有很好的控制.
- 反应的广泛基板范围和适用于具有挑战性的基板的可用性凸显了它的合成实用性.
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相关概念视频
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.
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.
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.
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.
Electrophilic Addition to Alkynes: Hydrohalogenation
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.
