Reinvigorating aza-Michael reactions under ionic liquid catalysis: a greener approach
View abstract on PubMed
Summary
This summary is machine-generated.Cholinium amino carboxylates demonstrate superior catalytic activity in aza-Michael reactions, offering improved yields and reaction rates. These ionic liquids show promise as efficient and stable alternatives for organic synthesis.
Area Of Science
- Green Chemistry
- Catalysis
- Organic Synthesis
Background
- Cholinium α-amino carboxylates are a class of ionic liquids known for their stability and favorable physical properties.
- Their application as catalysts in organic synthesis, particularly leveraging their dual role as solvents and catalysts, remains underexplored.
Purpose Of The Study
- To investigate the catalytic potential of cholinium α-amino carboxylates in aza-Michael reactions.
- To compare their efficiency against conventional methods and other ionic liquids, such as imidazolium-based ILs.
Main Methods
- Utilizing cholinium α-amino carboxylates as catalysts for aza-Michael reactions.
- Employing high-level computational analyses to elucidate reaction mechanisms.
Main Results
- Cholinium α-amino carboxylates demonstrated catalytic advantages, including low catalyst loading and accelerated reaction rates.
- Improved product yields were observed compared to conventional conditions and imidazolium-based ionic liquids.
- Evidence suggests catalysis occurs via multiple, cooperative non-covalent interactions.
Conclusions
- Cholinium α-amino carboxylates are effective catalysts for aza-Michael reactions, offering a greener and more efficient synthetic route.
- Their unique structural features facilitate cooperative non-covalent interactions, underpinning their catalytic efficacy.
- Further investigation into these ionic liquids for synthetic applications is warranted.
Related Concept Videos
Alkynes can be reduced to trans-alkenes using sodium or lithium in liquid ammonia. The reaction, known as dissolving metal reduction, proceeds with an anti addition of hydrogen across the carbon–carbon triple bond to form the trans product. Since ammonia exists as a gas (bp = −33°C) at room temperature, the reaction is carried out at low temperatures using a mixture of dry ice (sublimes at −78°C) and acetone.
When dissolved in liquid ammonia, an alkali metal,...
The attack of a nucleophile at the β carbon of an α,β-unsaturated carbonyl compound is called conjugate addition. Conjugate addition reactions of active methylene compounds, such as β-diketones, β-keto esters, β-keto nitriles, and α-nitro ketones, are called Michael addition reactions.
The reaction is catalyzed by a base that abstracts the acidic methylene hydrogen, generating a doubly-stabilized enolate ion that serves as the nucleophile or the Michael...
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...
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 acidic strength of hydrocarbons follows the order: Alkynes > Alkenes > Alkanes. The strength of an acid is commonly expressed in units of pKa — the lower the pKa, the stronger the acid. Among the hydrocarbons, terminal alkynes have lower pKa values and are, therefore, more acidic. For example, the pKa values for ethane, ethene, and acetylene are 51, 44, and 25, respectively, as shown here.
Ethane
(pKa = 51)
Ethene
(pKa = 44)
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.
Thermodynamic Stability
Catalytic hydrogenation reactions help evaluate the relative thermodynamic stability of hydrocarbons. For example, the heat of hydrogenation of acetylene is −176 kJ/mol, and that of ethylene is −137 kJ/mol. The higher exothermicity...

