![Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-(phosphinetriyl)tripiperidine]}palladium Under Mild Reaction Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F51444.jpg&w=3840&q=50)
Catalytic asymmetric cyclopropanation using bridged dirhodium tetraprolinates on solid support
Tadamichi Nagashima1, Huw M L Davies
1Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, New York 14260-3000, USA.
Organic Letters
|June 7, 2002
Summary
Dirhodium tetraprolinates immobilized on macroporous resins efficiently catalyze asymmetric cyclopropanation reactions. This method offers a robust approach for synthesizing chiral cyclopropanes from methyl aryldiazoacetates.
Area of Science:
- Catalysis
- Organic Chemistry
- Materials Science
Background:
- Asymmetric cyclopropanation is crucial for synthesizing chiral cyclopropanes.
- Developing efficient and recyclable catalysts is essential for sustainable synthesis.
- Immobilization of homogeneous catalysts can improve their stability and reusability.
Purpose of the Study:
- To investigate the efficacy of dirhodium tetraprolinates immobilized on macroporous polystyrene resins as catalysts for asymmetric cyclopropanation.
- To evaluate the performance of these heterogeneous catalysts in terms of activity, selectivity, and recyclability.
Main Methods:
- Synthesis of dirhodium tetraprolinates.
- Immobilization of dirhodium tetraprolinates onto highly cross-linked macroporous polystyrene resins.
- Asymmetric cyclopropanation reactions using methyl aryldiazoacetates and various alkenes.
- Analysis of reaction products using chiral chromatography.
Main Results:
- The immobilized dirhodium tetraprolinate catalysts demonstrated high activity and enantioselectivity in asymmetric cyclopropanation.
- The heterogeneous catalysts were easily recovered and reused multiple times without significant loss of performance.
- The polystyrene resin support provided a stable environment for the catalyst, preventing leaching.
Conclusions:
- Dirhodium tetraprolinates supported on macroporous polystyrene resins are highly effective heterogeneous catalysts for asymmetric cyclopropanation.
- This catalytic system offers a practical and sustainable alternative to homogeneous catalysts for the synthesis of chiral cyclopropanes.
More Related Videos
Related Concept Videos
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.
02:17Reduction 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...
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.
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
![[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F12417.jpg&w=3840&q=75)
01:16[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
01:29Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
Diels–Alder reactions between cyclic dienes locked in an s-cis configuration and dienophiles yield bridged bicyclic products.