从四基酸盐到aminoborylvinylidene-osmium复合物通过基尼尔-aminoboryl中间体
María L Buil1, Miguel A Esteruelas, Karin Garcés
1Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain. mbuil@unizar.es
Journal of the American Chemical Society
|January 29, 2011
概括
含有aminoboryl配体的奥斯复合物经历与和酸的转化. 这些反应产生了新的玻利基衍生物和维尼利丁复合物,在有机金属化学中展示了新的反应性.
科学领域:
- 有机金属化学 有机金属化学
- 无机化学 无机化学 有机化学
- 催化剂是一种催化剂.
背景情况:
- 奥斯复合物在合成转换中具有多功能.
- 四基酸配体提供独特的反应途径.
- 氨基和基连体是有机金属合成中的关键功能组.
研究的目的:
- 为了研究四基酸盐复合物与氨基和基因的反应性.
- 探索新型aminoboryl和amino(fluoro) boryl衍生物的形成.
- 在各种条件下研究这些复合物的后续转化.
主要方法:
- 奥斯四基酸盐复合物 (1) 与初级氨基 (氨酸,p-toluidine) 的反应.
- 用乙烯处理由此产生的阿米诺波里尔复合物.
- 进一步的反应与四黄酸 (HBF(4)),酸和一氧化碳 (CO).
- 产品的光谱表征 (NMR,X射线衍射) 的产品.
主要成果:
- 从复合物1和氨基酸中合成阿米诺玻利氧化复合物 (2,3) .
- 通过与乙烯的反应形成基尼尔-阿米诺玻利奥斯复合体 (4,5).
- 使用HBF转化为氨基基基物种 (6,7),使用HBF4).
- 在添加酸或CO时生成六坐标复合体 (8-11) .
- 观察1,3-转移导致aminoborylvinylidenes (12,13) 和相关的衍生物 (17,18).
结论:
- 奥四基酸盐复合物对氨基和基因表现出丰富的反应性.
- 奥斯复合物的多种功能化是可以实现的,导致aminoboryl,amino(fluoro) boryl和vinylidene衍生物.
- 这项研究突出了化学中的新型迁移插入和重新排列途径.
相关概念视频
03:08Hydroboration-Oxidation of Alkenes
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.
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
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.
02:36Regioselectivity and Stereochemistry of Hydroboration
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 stereochemistry.
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 stereochemistry.
02:44Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
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.
01:26Radical Substitution: Hydrogenolysis of Alkyl Halides with Tributyltin Hydride
Radical substitution reactions can be used to remove functional groups from molecules. The hydrogenolysis of alkyl halides is one such reaction, where the weak Sn–H bond in tributyltin hydride reacts with alkyl halides to form alkanes. Here, the reagent Bu3SnH yields tributyltin halide as a byproduct.
The bonds formed in this reaction are stronger than the bonds broken, making it energetically favorable. The reaction follows a radical chain mechanism similar to radical halogenation reactions,...
The bonds formed in this reaction are stronger than the bonds broken, making it energetically favorable. The reaction follows a radical chain mechanism similar to radical halogenation reactions,...
01:16Amines to Alkenes: Hofmann Elimination
Alkenes can be obtained from amines via an E2 elimination. The amine is first converted into a good leaving group, such as a quaternary ammonium salt. This is accomplished by treating the amine with an excess of alkyl halide, which results in a halide salt. Next, the halide salt is transformed into a hydroxide salt that functions as a base to enable elimination.
Under thermal conditions, the hydroxide can abstract a proton from the β carbon; this generates an alkene with the simultaneous...
Under thermal conditions, the hydroxide can abstract a proton from the β carbon; this generates an alkene with the simultaneous...