Combining proline and ‘click chemistry’: a class of versatile organocatalysts for the highly diastereo- and enantioselective Michael addition in water

Yan, Ze‐Yi; Niu, Yan‐Ning; Wei, Hai‐Long; Wu, Luyong; Yan-hua, Zhao; Liang, Yong‐Min

doi:10.1016/j.tetasy.2006.12.003

Cited by 97 publications

(13 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The reactions were undertaken with 10 mol% Among the various carbonyl compounds used as substrates for the Michael addition to trans-β-nitrostyrene, acetone furnished 85% yield and low (52%) enantioselectivity in a shorter reaction period. This result resembles the one found by Yan et al using a similar 1,2,3-triazole catalyst [90]. Cyclopentanone was often reported to give low selectivity for non-immobilized catalysts under Michael addition to trans-β-nitrostyrenes.…”

Section: Application Of 123-triazolium Ionic Liquids In Catalysissupporting

confidence: 88%

Chemistry of 1,2,3-Triazolium Salts

Yacob¹,

Liebscher²

2014

Topics in Heterocyclic Chemistry

View full text Add to dashboard Cite

1,2,3-Triazolium salts have been known for a long time. However, their potential as ionic liquids and catalysts was recognized only quite recently. 1,2,3-Triazolium ionic liquids can serve as solvent, as catalyst, as hosts in anion recognition and as components of molecular machines. The major trends in application involve tethering catalytically active species such as (S)-proline with triazolium ionic liquids and the use as anion recognizing organocatalysts. Such catalysts are interesting not only due to their recyclability but also because of their outstanding tuneable properties. They can have wide liquid range, thermal stability, tuneable polarity, low flammability, tuneable solubility and low vapour pressure along with ease of separation. The syntheses of 1,2,3-triazolium salts are mainly based on the copper catalysed azide-alkyne cycloaddition (CuAAC) as the most famous click reaction, and subsequent N-alkylation of the resulting 1,2,3-triazoles. This synthetic route has the advantage of having four structural units, i.e. the alkyne, the azide, the alkylating agent and the counter anion that can be manipulated in order to tune the properties of the resulting ionic liquid. Unlike the imidazolium ionic liquids 1,2,3-triazolium salts do not have an acidic proton at position 2, which could make them inappropriate for reactions under basic conditions. The low acidity of 1,2,3triazolium salts in position 4 is exploited in the formation of 1,2,3-triazol-4-ylidene metal complexes with marked catalytic properties.

show abstract

Section: Application Of 123-triazolium Ionic Liquids In Catalysissupporting

confidence: 88%

Chemistry of 1,2,3-Triazolium Salts

Yacob¹,

Liebscher²

2014

Topics in Heterocyclic Chemistry

View full text Add to dashboard Cite

show abstract

“…Pyrrolidine -based organocatalyst 161 gave excellent results when used in 10 mol% in chloroform or water without additives [129] or under neat conditions in 10 mol% and in the presence of TFA (2.5 mol%) [130] . However, no recycling experiments were carried out.…”

Section: Ionic Liquid -Anchored Organocatalystsmentioning

confidence: 99%

Recyclable Organocatalysts in Asymmetric Reactions

Gruttadauria

Giacalone

Noto

2011

Catalytic Methods in Asymmetric Synthesis

View full text Add to dashboard Cite

“…The preferred chiral secondary amines are substituted pyrrolidines with a myriad of substituents in the 2‐position. A by no means complete or chronological collection is presented in Scheme for illustration purposes.…”

Section: Introductionmentioning

confidence: 99%

“…The regioselectivity has been discussed in terms of higher stability of the corresponding enamine with a trisubstituted double bond ( Scheme ). Besides the explicit discussions of these remarkable phenomena, a difference in the stability of the enamines is often assumed implicitly when suggesting transition state models in which the enamines adopt an s‐ trans or s‐ cis conformation …”

Section: Introductionmentioning

confidence: 99%

Rigorous Conformational Analysis of Pyrrolidine Enamines with Relevance to Organocatalysis

Husch

Seebàch

Beck

et al. 2017

Helvetica Chimica Acta

View full text Add to dashboard Cite

It has been suggested that the origin of regio-and stereoselectivity in Michael additions of pyrrolidine enamines is achieved by thermodynamic rather than kinetic control through distinct conformational preferences of the enamines. We assess this proposal by elaboration of a computational protocol that warrants sufficient accuracy. The small energy differences between the conformers necessitate a high accuracy of the electronic structure method which, in addition, must allow for computationally feasible calculations of a large number of conformers. Our protocol is based on density functional theory which we validated against explicitly correlated coupled cluster theory. The results are in agreement with the available experimental data, but illustrate that conformational preferences determined for one enamine are not readily transferable to other types of enamines. We found that an appropriate conformational sampling is inevitable to arrive at meaningful conclusions. Most prominently, s-cis and strans conformers are similarly stable for aldehyde-and ketone-derived enamines. The regio-and stereoselectivity in Michael additions of pyrrolidine-derived enamines can not be explained by pronounced stability differences of the enamine isomers and conformers in general, disproving the thermodynamic-control hypothesis. The elucidation of the origin of regio-and stereoselectivity requires further theoretical investigations of the elementary steps of Michael additions.

show abstract

Combining proline and ‘click chemistry’: a class of versatile organocatalysts for the highly diastereo- and enantioselective Michael addition in water

Cited by 97 publications

References 41 publications

Chemistry of 1,2,3-Triazolium Salts

Chemistry of 1,2,3-Triazolium Salts

Recyclable Organocatalysts in Asymmetric Reactions

Rigorous Conformational Analysis of Pyrrolidine Enamines with Relevance to Organocatalysis

Contact Info

Product

Resources

About