Asymmetric alkene epoxidation by Mn(III)salen catalyst in ionic liquids

Teixeira, Jorge; Silva, Ana Rosa; Branco, Luı́s C.; Afonso, Carlos A. M.; Freire, Cristina

doi:10.1016/j.ica.2010.06.018

Cited by 20 publications

(14 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As expected, reaction solvent plays a crucial role in the asymmetric epoxidation of chromene. The reaction time of ionic liquid system is very short, and the product can be easily separated due to the solvent power of the ionic liquid for many organic and inorganic substances compared with the well-documented reaction time of Jacobson type chiral catalysts [39,40]. The experimental results show these complexes are effective catalysts for the asymmetric epoxidation of chromenes in the presence of ionic liquid.…”

Section: Catalytic Activity Studiesmentioning

confidence: 95%

Asymmetric Epoxidation of Chromenes Using Manganese(III) Complexes with Novel Chiral Salen-like Schiff Base Ligands

et al. 2012

View full text Add to dashboard Cite

Three novel chiral salen-like schiff base ligands and their Mn(III) complexes containing different amino acid unit have been synthesized and characterized. Asymmetric epoxidation reactions show these complexes are effective catalysts for the chromenes with buffer NaOCl as terminal oxidant and pyridine N-oxide as co-catalyst in the presence of ionic liquid. Good-to -excellent enantioselectivity and acceptable yields can be obtained under optimum reaction conditions. Catalyst 4c gives the highest ee (95%) for 6-chloro-2,2-dimethylchromene among these catalytic performances. Furthermore, compared the enantioselectivity of catalyst 4c with the other two catalysts 4a and 4b, the positive experimental results suggest that the steric effect of the ligands plays an important role in the asymmetric catalysis.

show abstract

Section: Catalytic Activity Studiesmentioning

confidence: 95%

Asymmetric Epoxidation of Chromenes Using Manganese(III) Complexes with Novel Chiral Salen-like Schiff Base Ligands

et al. 2012

View full text Add to dashboard Cite

show abstract

“…Severaly ears later,F reire and co-workersc onducted the epoxidation of 6-cyano-2,2-dimethylchromene by using the same catalyst. [70] The authors employs odium hypochlorite as an oxygen source and [C 4 mim][PF 6 ]a st he most suitable solvent for this transformation.T he authorsn ote that the catalytic performance is strongly influenced by the physical properties and structure of the ionic liquid:r eplacement of the acidic proton in the 2-position of the imidazolium ring with as uitable group significantly enhances the ee values. Also, an increase in the size of the cation of the ionic liquid decreases the ee values.…”

Section: Epoxidationo Fo Lefinmentioning

confidence: 99%

Ionic Liquids in Asymmetric Synthesis: An Overall View from Reaction Media to Supported Ionic Liquid Catalysis

et al. 2018

View full text Add to dashboard Cite

Ionic liquids, as a special class of organic compounds, have attracted ever‐growing interest in recent years. They have been employed in many organic transformations as a green alternative to volatile organic solvents and as a catalyst to modify catalytic activity and recyclability. Recent developments have demonstrated that ionic liquids might also have many benefits in asymmetric reactions. In this review, we survey the use of ionic liquids in asymmetric transformations, including the use of ionic liquids as reaction media in asymmetric reactions, ionic‐liquid‐tagged chiral catalysts for use in asymmetric synthesis, and supported ionic liquid catalysts in asymmetric transformations.

show abstract

“…Since the discovering of Jacobsen catalyst, many researches focused on how to further improve its catalytic activity and enantioselectivity. To achieve this purpose, an increasing number of studies were performed by introducing different substituents on the salicylidene ring or diimine bridge of the salen unit . It provides a way to enhance the steric hindrance of the catalyst and results in higher enantioselectivity.…”

Section: Introductionmentioning

confidence: 99%

The influence of axial ligands on the catalytic activity and enantioselectivity of salen‐Mn complexes in the asymmetric epoxidation

Liu

2019

J of Physical Organic Chem

View full text Add to dashboard Cite

The asymmetric epoxidation of indene catalyzed by Jacobsen catalysts with different axial ligands (Cl − , Br − , OAc − , CF 3 CO 2 − , N(CH 3 ) 2 − , and NO 3 − ) was theoretically investigated. The spin states and approach vectors were taken into consideration. The axial ligands can affect the steric conformation of the catalysts. Furthermore, the structure distortion during the formation of the transition state is responsible for the enantioselectivity, and this distortion is also highly related to the axial ligands. These ligands have nonnegligible influence on both the catalytic activity and enantioselectivity. Changing the axial ligand can even turn the enantioselectivity from (S, R)-to (R, S)-enantiomer. The influence of axial ligand on the enantioselectivity is comparable with that induced by the salicylidene ring modification. Controlling the catalytic activity and enantioselectivity of salen-Mn complexes by simply changing the axial ligand deserves to be paid more attention.

show abstract

Asymmetric alkene epoxidation by Mn(III)salen catalyst in ionic liquids

Cited by 20 publications

References 45 publications

Asymmetric Epoxidation of Chromenes Using Manganese(III) Complexes with Novel Chiral Salen-like Schiff Base Ligands

Asymmetric Epoxidation of Chromenes Using Manganese(III) Complexes with Novel Chiral Salen-like Schiff Base Ligands

Ionic Liquids in Asymmetric Synthesis: An Overall View from Reaction Media to Supported Ionic Liquid Catalysis

The influence of axial ligands on the catalytic activity and enantioselectivity of salen‐Mn complexes in the asymmetric epoxidation

Contact Info

Product

Resources

About