不对称的,用一种新型的bis(phosphine) 氧化物奇拉连接剂合成alpha-chiral胺的催化合成
Alessandro A Boezio1, Julien Pytkowicz, Alexandre Côté
1Département de Chimie, Université de Montréal, P.O. Box 6128, Station Downtown, Montréal (Québec), Canada H3C 3J7.
Journal of the American Chemical Society
|November 20, 2003
概括
一个新型的配体,BozPHOS,使得从N-phosphinoylimines和dialkylzinc试剂中有效的铜催化合成α-chiral amines. 这种方法提供了高的产量和酶选择性,即使与较低的反应性二甲基,使用低的催化剂负载.
科学领域:
- 有机化学 有机化学
- 不对称的催化剂.
- 有机金属化学 有机金属化学
背景情况:
- 胺胺是制药和农业化学品中至关重要的构建块.
- 有效的催化方法用于合成基纯氨酸是非常受欢迎的.
- 铜催化添加到伊米因是获得奇拉胺的有希望的途径.
研究的目的:
- 为铜催化不对称的加法反应开发一种新型,高效的配体.
- 为了证明新连接体BozPHOS在α-奇拉胺的合成中的实用性.
- 为了研究联体的性能与具有挑战性的基质,如二甲基.
主要方法:
- 用铜催化添加对N-phosphinoylimines的基试剂.
- 使用了一种新开发的氧化联体,Me-DuPHOS氧化 (BozPHOS).
- 对反应条件的选以优化产量,酶选择性和催化剂负荷.
主要成果:
- 博兹福斯 (BozPHOS) 作为铜催化反应中的配体,具有很高的疗效.
- 实现了高产量和优异的对阿尔法 - 奇拉胺胺的酶选择性 (ee).
- 这一过程即使使用不那么有反应性的二甲基,也是有效的.
- 较低的催化剂负荷 (3 mol %) 足以形成较高的产品.
结论:
- Me-DuPHOS单氧化物 (BozPHOS) 是一种高效的连接体,用于胺的铜催化不对称合成.
- 这种方法提供了一个强大而有效的途径,以获得有价值的性氨基构建块.
- 开发的工艺提供了显著的优势,包括高产量,广泛的基质范围,以及在低催化剂负载下优异的酶选择性.
相关概念视频
Chirality at Nitrogen, Phosphorus, and Sulfur
Chirality is most prevalent in carbon-based tetrahedral compounds, but this important facet of molecular symmetry extends to sp3-hybridized nitrogen, phosphorus and sulfur centers, including trivalent molecules with lone pairs. Here, the lone pair behaves as a functional group in addition to the other three substituents to form an analogous tetrahedral center that can be chiral.
A consequence of chirality is the need for enantiomeric resolution. While this is theoretically possible for all...
A consequence of chirality is the need for enantiomeric resolution. While this is theoretically possible for all...
Prochirality
The concept of prochirality leads to the nomenclature of the individual faces of a molecule and plays a crucial role in the enantioselective reaction. It is a concept where two or more achiral molecules react to produce chiral products. A typical process is the reaction of an achiral ketone to generate a chiral alcohol. Here, the achiral reactant reacts with an achiral reducing agent, sodium borohydride, to generate an equimolar mixture of the chiral enantiomers of the product. For example, an...
Oxidation 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.
Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
Preparation of 1° Amines: Azide Synthesis
Direct alkylation of ammonia produces polyalkylated amines, along with a quaternary ammonium salt. To exclusively prepare primary amines, the azide synthesis method can be used.
Azide ions act as good nucleophiles and react with unhindered alkyl halides to form alkyl azides. Alkyl azides do not participate in further nucleophilic substitution reactions, thereby eliminating the chances of polyalkylated products. Alkyl azides are reduced by hydride-based reducing agents, like lithium aluminum...
Azide ions act as good nucleophiles and react with unhindered alkyl halides to form alkyl azides. Alkyl azides do not participate in further nucleophilic substitution reactions, thereby eliminating the chances of polyalkylated products. Alkyl azides are reduced by hydride-based reducing agents, like lithium aluminum...
Preparation of 1° Amines: Gabriel Synthesis
Direct alkylation is not a suitable method for synthesizing amines because it produces polyalkylated products. Gabriel synthesis is the most preferred method to exclusively make primary amines. The method uses phthalimide, which contains a protected form of nitrogen that participates in alkylation only once to predominantly give primary amines.
Strong bases like NaOH or KOH deprotonate the phthalimide to form the corresponding anion, which acts as a nucleophile. Further, the anion attacks an...
Strong bases like NaOH or KOH deprotonate the phthalimide to form the corresponding anion, which acts as a nucleophile. Further, the anion attacks an...


