甲基酸盐的异构性氧碳化酶的机理特征
Philipp Roesle1, Christoph J Dürr, Heiko M Möller
1Chair of Chemical Materials Science, Department of Chemistry, University of Konstanz, 78464 Konstanz, Germany.
Journal of the American Chemical Society
|October 18, 2012
概括
这项研究详细介绍了使用三复合体的甲基酸盐异构化和碳化酶的催化机制. 这项研究阐明了关键的中间体和反应途径,为选择性质形成提供了洞察力.
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.
- 有机合成 有机合成
背景情况:
- 复合物是有机转化中的关键催化剂.
- 了解反应机制是开发高效合成方法的关键.
- 烯的氧碳化和异构化是重要的工业过程.
研究的目的:
- 通过使用特定的三甲酸前体,研究甲基酸的异构性氧化碳化机制.
- 识别和描述参与催化循环的反应性中间体.
- 探索线性与分支产品形成的选择性.
主要方法:
- 一个三复合物的合成和特征 [(P^P) Pd(OTf) ](+) ((OTf) ((-) (1).
- 复合物的与酒精 (甲醇,甲醇) 和的反应,形成化物和化物种.
- 使用德化物复合物的甲基酸盐的异构化研究.
- 使用同位素标记基板的机理研究 (1-(13) 标记C的1 - 八, (13) CO) 和DFT计算.
- 分析产品分布和反应动力学.
主要成果:
- 三复合物作为机械学研究的有效前体.
- 甲基酸盐的异构化到热力学平衡是快速的.
- 观察到线性和分支基物种的形成.
- 碳化导致线性和分支的酸中间体.
- 对于线性和分支产品,DFT研究表明中间体形成的可逆性和不同的甲醇化障碍物.
- 线性乙-中间体的选择性甲醇化产生线性二聚,而分支中间体保持不反应.
结论:
- 这项研究提供了对甲基酸盐的异体化氧化碳化反应的详细机制理解.
- 催化剂通过不同的途径促进了快速的烯酸异构化和线性产物的选择性形成.
- 动力和计算数据突出显示了控制产品选择性的热力学和动力学因素,特别是对线性二聚形成的偏好.
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.
01:14Alkylation of β-Diester Enolates: Malonic Ester Synthesis
Malonic ester synthesis is a method to obtain α substituted carboxylic acids from ꞵ-diesters such as diethyl malonate and alkyl halides.
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.
02:04Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
Diols are compounds with two hydroxyl groups. In addition to syn dihydroxylation, diols can also be synthesized through the process of anti dihydroxylation. The process involves treating an alkene with a peroxycarboxylic acid to form an epoxide. Epoxides are highly strained three-membered rings with oxygen and two carbons occupying the corners of an equilateral triangle. This step is followed by ring-opening of the epoxide in the presence of an aqueous acid to give a trans diol.
02:36Oxymercuration-Reduction of Alkenes
Oxymercuration–reduction of alkenes is one of the major reactions converting alkenes to alcohols. It involves the hydration of alkenes with mercuric acetate in a mixture of tetrahydrofuran and water, forming an organomercury adduct. This is followed by a demercuration step in which the adduct is reduced to an alcohol using sodium borohydride.