玻利三玻酸盐:合成,结构和反应性作为离子,有机金属和激素反应中的减电剂
Kyoko Nozaki1, Yoshitaka Aramaki, Makoto Yamashita
1Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Bunkyo-ku, Tokyo 113-8656, Japan. nozaki@chembio.t.u-tokyo.ac.jp
Journal of the American Chemical Society
|August 4, 2010
概括
研究人员合成了一种新型的甲,一种独特的化合物,在甲框架上具有替代物. 这一新类化合物表现出多样化的反应性,在各种化学转化中充当多功能还原剂.
科学领域:
- 有机金属化学 有机金属化学
- 化学 化学
- 合成化学 合成化学
背景情况:
- 化物是有机合成中必不可少的还原剂.
- N-异环碳玻兰是具有独特性质的异电子类型.
- 开发新的基试剂扩大了合成能力.
研究的目的:
- 为了合成和表征一种新的基替代水化物.
- 调查新化合物中的结构特征和粘合.
- 探索这种新型类型的还原剂的反应性和潜在应用.
主要方法:
- 1,3-bis(2,6-diisopropylphenyl)-2,3-dihydro-1H-1,3,2-diazaborol-2-ide与的反应.THF.与进行反应.
- 使用NMR光谱学 ((11) B, (1) H, (7) Li) 和其他分析技术进行完整的表征.
- 结晶学分析以确定二维结构和结合相互作用.
主要成果:
- 成功合成了 [1,3-bis(2,6-二异甲) -2,3-二-1H-1,3,2-二博醇-2-]三博酸,这是第一个博化物.
- 该化合物结晶为具有Li---HB相互作用的二聚体,缺乏桥梁B-H键.
- 证明了多种反应性,包括离子,有机金属 (Pd-催化) 和各种化物激进减少.
结论:
- 新的甲类代表了化学的重大进步.
- 这种化合物表现出多样化的还原性,弥合了传统的化物和N-异环碳酸之间的差距.
- 独特的结构和电子特性表明在有机合成和材料科学中具有广泛的应用.
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.
02:23Alcohols from Carbonyl Compounds: Reduction
Reduction is a simple strategy to convert a carbonyl group to a hydroxyl group. The three major pathways to reduce carbonyls to alcohols are catalytic hydrogenation, hydride reduction, and borane reduction.
Catalytic hydrogenation is similar to the reduction of an alkene or alkyne by adding H2 across the pi bond in the presence of transition metal catalysts like Raney Ni, Pd–C, Pt, or Ru. Aldehydes and ketones can be reduced by this method, often under mild to moderate heat (25–100°C) and...
Catalytic hydrogenation is similar to the reduction of an alkene or alkyne by adding H2 across the pi bond in the presence of transition metal catalysts like Raney Ni, Pd–C, Pt, or Ru. Aldehydes and ketones can be reduced by this method, often under mild to moderate heat (25–100°C) and...
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,...
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.
01:33Radical Reactivity: Intramolecular vs Intermolecular
Radical reactions can occur either intermolecularly or intramolecularly. In an intermolecular radical reaction, a nucleophilic radical adds to an electrophilic alkene or vice versa. In such reactions, the radical and generally the alkene, which is also called the radical trap, are two different molecules. Additionally, for such intermolecular reactions to occur, the radical trap must be active, present in an excess concentration, and the radical starting material must have a weak carbon–halogen...