催化不对称合成合性合性 Ester 的催化不对称合成
Stefan F Kirsch1, Larry E Overman
1Department of Chemistry, 516 Rowland Hall, University of California, Irvine, California 92697-2025, USA.
Journal of the American Chemical Society
|March 3, 2005
概括
的3-基-1-基因是从使用新型催化剂的前性基因合成的. 这种高效的酶选择反应发生在室温下,具有高立体控制.
科学领域:
- 有机化学 有机化学
- 不对称的合成方法
- 有机金属化学 有机金属化学
背景情况:
- 普罗基拉 (Z) -2-基-1-醇是有价值的合成中间体.
- 在有机合成中,开发高效的催化方法来进行酶选择性转换至关重要.
研究的目的:
- 开发一种新型的催化系统,用于奇拉性3-基-1-基的酶选择性合成.
- 调查这种新变化的范围和机制.
主要方法:
- 普罗基拉 (Z) - 2 - - 基-1-醇的三乙胺衍生物与碳素酸的反应.
- 使用一种性催化剂,di-mu-acetatobis[(eta5-(S) -(pR)-2-(2'-(4'-甲基乙烯) 氧化乙烯) cyclopentadienyl,1-C,3'-N) ((eta4-tetraphenylcyclobutadiene) cobalt]dipalladium (COP-OAc) 或其反体.
主要成果:
- 获得了性3 - 基-1-基的高度纯度.
- 反应表明了广泛的基质范围和可预测的高立体感应.
- 该过程是高效的,在室温下运行,基质度高,催化剂负载低.
结论:
- 已经建立了一种新且高效的方法,用于合成奇拉性3-基-1-基的enantioselective合成.
- 反应很可能通过一种新的催化机制进行,这需要进一步调查.
相关概念视频
Acid Halides to Esters: Alcoholysis
Alcoholysis is a nucleophilic acyl substitution reaction in which an alcohol functions as a nucleophile. Acid halides react with alcohol to produce esters. The mechanism proceeds in three steps:
Esters to Carboxylic Acids: Acid-Catalyzed Hydrolysis
Hydrolysis of esters under acidic conditions proceeds through a nucleophilic acyl substitution. In the presence of excess water, the reaction proceeds in a reversible manner, forming carboxylic acids and alcohols.
During hydrolysis, the ester is first activated towards nucleophilic attack through the protonation of the carboxyl oxygen atom by the acid catalyst. The protonation makes the ester carbonyl carbon more electrophilic. In the next step, water acts as a nucleophile and adds to the...
During hydrolysis, the ester is first activated towards nucleophilic attack through the protonation of the carboxyl oxygen atom by the acid catalyst. The protonation makes the ester carbonyl carbon more electrophilic. In the next step, water acts as a nucleophile and adds to the...
Esters to β-Ketoesters: Claisen Condensation Overview
Regular Claisen condensation is a base-promoted reaction involving identical esters with two α hydrogens, condensing to produce β-ketoesters. It is a nucleophilic acyl substitution reaction wherein one of the ester molecules, upon deprotonation by the base, forms a nucleophilic enolate ion, while the other molecule serves as an electrophile.
β-Dicarbonyl Compounds via Crossed Claisen Condensations
Crossed Claisen condensations are base-promoted reactions between two different ester molecules producing β-dicarbonyl compounds. The reaction involving esters, with both containing α hydrogen, results in a mixture of four different products that are difficult to isolate. This reduces the synthetic utility of the reaction.
Esters to β-Ketoesters: Claisen Condensation Mechanism
Regular Claisen condensation involves the synthesis of β-ketoesters by combining identical ester molecules bearing two α hydrogens in the presence of an alkoxide base. The reaction commences with the deprotonation of the acidic α hydrogen by the base to form a resonance stabilized ester enolate. This nucleophilic ion then attacks the carbonyl center of another ester molecule to generate a tetrahedral alkoxide intermediate. Next, the expulsion of the alkoxide group from the intermediate restores...
Carboxylic Acids to Esters: Acid-Catalyzed (Fischer) Esterification Mechanism
Carboxylic acids react with alcohols to yield esters via an acid-catalyzed condensation reaction called Fischer esterification. This is a nucleophilic acyl substitution reaction that proceeds via a tetrahedral intermediate, where a water molecule is eliminated as the leaving group.


