铁催化区域选择性二氧化对-二乙烯
Yong Wang1, Yuxuan Li1, Lei Wang1
1Department of Chemistry and the Hong Kong Branch of Chinese National Engineering Research Centre for Tissue Restoration & Reconstruction, The Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon 999077, Hong Kong SAR, China.
Journal of the American Chemical Society
|January 19, 2023
概括
这项研究引入了一种新方法,用于用α-hetero替代剂合成gem-diboryl化合物. 新的α-二氧化反应有效地产生了高度替代的碳中心,扩大了合成的可能性.
科学领域:
- 有机化学
- 有机化学
背景情况:
- 1,1-二 (gem-diboryl) 化合物是关键的合成中间体.
- 之前的研究主要集中在缺乏α-hetero替代物的gem-diboryl基.
- 含有α-替代物的gem-diboryl化合物具有多功能性,但难以获得.
研究的目的:
- 开发了第一个直接的阿尔法二基因.
- 为了能够有效地合成gem-diboryl, hetero-和tetra-substituted碳中心.
- 为多步合成提供实用和原子经济的替代方案.
主要方法:
- 采用了一种新型的异基因α-二氧化反应.
- 作为基因的催化剂.
- 进行了对照实验和DFT计算以阐明反应机制.
主要成果:
- 实现了高效的 gem-diboryl, hetero- 和 tetra-substituted 碳中心的构建.
- 在 thioalkynes 的二化中表现出优异的α区域选择性.
- 确定了一种两步顺序的化机制,第二步具有更高的能量屏障.
结论:
- 开发了一种简单,实用,温和和原子经济的合成α-hetero-substituted gem-diboryl化合物的方法.
- 这种反应可以进入以前无法进入的高度拥挤的α-硫-二碳中心.
- 这些发现为现有的有机化学合成策略提供了有价值的补充.
相关概念视频
02:36Regioselectivity and Stereochemistry of Hydroboration
8.3K
A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...
8.3K
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
18.6K
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.
18.6K
03:08Hydroboration-Oxidation of Alkenes
8.7K
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.
8.7K
02:35Electrophilic Addition to Alkynes: Hydrohalogenation
10.1K
Electrophilic addition of hydrogen halides, HX (X = Cl, Br or I) to alkenes forms alkyl halides as per Markovnikov's rule, where the hydrogen gets added to the less substituted carbon of the double bond. Hydrohalogenation of alkynes takes place in a similar manner, with the first addition of HX forming a vinyl halide and the second giving a geminal dihalide.
10.1K
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
7.9K
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.
7.9K
02:44Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
10.6K
Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.
10.6K