协调诱导的对碳酸盐的立体控制:非对称的减氧拉塞米三级酒精
Mayuko Isomura1, David A Petrone1, Erick M Carreira1
1ETH Zürich , Vladimir-Prelog-Weg 3 , HCI, 8093 Zürich , Switzerland.
Journal of the American Chemical Society
|February 21, 2019
概括
研究人员开发了一种新的对接策略,用于不对称的催化,使三级碳酸的立体选择性反应成为可能. 这种方法实现了第一个具有高选择性的三级酒精的降解脱氧.
科学领域:
- 有机化学
- 催化剂
- 不对称的合成
背景情况:
- 在催化过程中,很难对三级碳酸盐进行立体选择性控制.
- 这种限制限制了它们在不对称合成中作为中间体的使用.
研究的目的:
- 开发一种对三级碳酸的立体选择性核友攻击方法.
- 实现第一个三级酒精的反选择性减氧.
主要方法:
- 使用可逆基质协调与性过渡金属催化剂的对接策略.
- 作为化物来源使用了一种新型的汉茨赫类似物.
- 使用深入的机械研究.
主要成果:
- 实现对三级碳酸的高度立体选择性核友攻击.
- 首次证明了高达96%的三级酒精的反抗选择性减氧.
- 获得高区域选择性 (高达>50:1 rr).
结论:
- 这种对接策略能够精确地对碳酸中间体进行立体化学控制.
- 这一突破为涉及三级碳酸的不对称催化开辟了新的途径.
- 开发的方法提供了对三级酒精的反选择性脱氧的可靠途径.
相关概念视频
Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
3.9K
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...
3.9K
Esters to Alcohols: Hydride Reductions
4.7K
Esters are reduced to primary alcohols when treated with a strong reducing agent like lithium aluminum hydride. The reaction requires two equivalents of the reducing agent and proceeds via an aldehyde intermediate.
Lithium aluminum hydride is a source of hydride ions and functions as a nucleophile. The mechanism proceeds in three steps. Firstly, the nucleophilic hydride ion attacks the carbonyl carbon of the ester to form a tetrahedral intermediate. Subsequently, the carbonyl group re-forms,...
Lithium aluminum hydride is a source of hydride ions and functions as a nucleophile. The mechanism proceeds in three steps. Firstly, the nucleophilic hydride ion attacks the carbonyl carbon of the ester to form a tetrahedral intermediate. Subsequently, the carbonyl group re-forms,...
4.7K
Alcohols from Carbonyl Compounds: Reduction
12.3K
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...
12.3K
Carbocations
13.6K
Carbocations are one of the reaction intermediates formed during several nucleophilic substitutions or elimination reactions. A carbocation is an electron-deficient species with the central carbon atom having six electrons and three bonded atoms. The central carbon in a carbocation is sp2 hybridized with trigonal planar geometry. It has an empty p orbital perpendicular to the plane of the structure that can accept electrons. Thus, carbocations act as strong electrophiles and may react with any...
13.6K
Carboxylic Acids to Primary Alcohols: Hydride Reduction
5.0K
Carboxylic acids, upon reaction with strong reducing agents such as lithium aluminum hydride followed by hydrolysis, undergo reduction to form primary alcohols.
5.0K
Acid Halides to Alcohols: LiAlH4 Reduction
4.0K
Acid halides are reduced to alcohols in the presence of a strong reducing agent like lithium aluminum hydride.
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
4.0K


