asymmetric organocatalysis
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Catalysts ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 101
Author(s):  
Sandra Ardevines ◽  
Eugenia Marqués-López ◽  
Raquel P. Herrera

Nowadays, the development of new enantioselective processes is highly relevant in chemistry due to the relevance of chiral compounds in biomedicine (mainly drugs) and in other fields, such as agrochemistry, animal feed, and flavorings. Among them, organocatalytic methods have become an efficient and sustainable alternative since List and MacMillan pioneering contributions were published in 2000. These works established the term asymmetric organocatalysis to label this area of research, which has grown exponentially over the last two decades. Since then, the scientific community has attended to the discovery of a plethora of organic reactions and transformations carried out with excellent results in terms of both reactivity and enantioselectivity. Looking back to earlier times, we can find in the literature a few examples where small organic molecules and some natural products could act as effective catalysts. However, with the birth of this type of catalysis, new chemical architectures based on amines, thioureas, squaramides, cinchona alkaloids, quaternary ammonium salts, carbenes, guanidines and phosphoric acids, among many others, have been developed. These organocatalysts have provided a broad range of activation modes that allow privileged interactions between catalysts and substrates for the preparation of compounds with high added value in an enantioselective way. Here, we briefly cover the history of this chemistry, from our point of view, including our beginnings, how the field has evolved during these years of research, and the road ahead.


Synlett ◽  
2022 ◽  
Author(s):  
Byungjun Kim ◽  
Yongjae Kim ◽  
Sarah Yunmi Lee

AbstractBecause of the versatility of chiral 1,5-dicarbonyl structural motifs, the development of stereoselective Michael additions of arylacetic acid derivatives to electron-deficient alkenes is an important challenge. Over recent decades, an array of enantio- and diastereoselective methods of this type have been developed through the use of chiral organocatalysts. In this article, three distinct strategies in this research area are highlighted. Catalytic generation of either a chiral iminium electrophile (iminium catalysis) or a chiral enolate nucleophile (Lewis­ base catalysis) has allowed the efficient construction of stereogenic C–C bonds. We also introduce a synergistic catalytic approach involving the merger of these two catalytic cycles that provides selective access to all four stereoisomers of products with vicinal stereocenters.1 Introduction2 Iminium Catalysis3 Lewis Base Catalysis4 Synergistic Organocatalysis5 Summary


2021 ◽  
Author(s):  
András A. Gurka

Abstract During the course of my research in asymmetric organocatalysis the inversion of enantioselectivity was observed in the asymmetric aldol reactions of acetone with different aldehydes catalyzed by amphiphilic proline derivatives in aqueous media varying only achiral components. It was not possible to explain the explored dual stereocontrol with the existing models, therefore I proposed a new mechanism for asymmetric aldol reactions catalyzed by l-amino acid derivatives in aqueous media and explained the explored phenomenon of inversion of enantioselectivity with different structures of micelle-stabilized transition state described as a metal-free version of the Zimmermann-Traxler model with explicit participation of a water molecule. Contrary to the existing models, according to the proposed mechanism the formation of new bonds proceeds directly in the transition state stabilized by a water molecule without the additional step of product iminium ion hydrolysis. The proposed mechanism has universal character, it is consistent with experimental results and general theoretical conceptions and it is applicable to all enamine-based asymmetric organocatalytic reactions carried out not only in aqueous, but in organic media as well, because the initial step of catalytic cycle, which involves the formation of an enamine from the carbonyl compound and proline (derivative), liberates one water molecule.


Author(s):  
Istvan Hargittai

AbstractThe 2021 Nobel Prize in Chemistry was awarded jointly to Benjamin List and David MacMillan “for the development of asymmetric organocatalysis.” This choice was remarkable for a number of reasons. It singled out a very “chemical” discovery, whereas in recent years, the chemistry prizes often went for discoveries in biochemistry, and it singled out two relatively young men. The concept of asymmetric organocatalysis has been around since the late 1920s, and in the early 1970s, even proline was recognized as capable of playing the role of an enzyme. Nonetheless, asymmetric organocatalysis has found major applications since about the year 2000 due to the discoveries and activities of the new laureates and their colleagues.


Author(s):  
Armando Carlone ◽  
Luca Bernardi ◽  
Peter McCormack ◽  
Tony Warr ◽  
Srinivas Oruganti ◽  
...  

Synlett ◽  
2021 ◽  
Author(s):  
Xiang Wu

Asymmetric organocatalysis is emerging as an elegant tool for accelerating chemical reactions and creating specific types of molecules. Chiral Brønsted acid catalysis is an important area of organocatalysis. Recently we described a chiral Brønsted acid (N-triflyl phosphoramide) catalyzed intramolecular iminium ion cyclization reaction of 2-alkenylbenzaldimines for the synthesis of chiral 1-aminoindenes and tetracyclic 1-aminoindanes in good yields and high enantioselectivities. The obtained 1-aminoindene can be utilized as useful synthetic intermediate for synthesis of (S)-rasagiline, an effective drug for the symptomatic treatment of Parkinson's disease. And the obtained tetracyclic 1-aminoindanes are the skeleton of homoisoflavanoid natural products such as brazilin.


Synthesis ◽  
2021 ◽  
Author(s):  
Carlos Alberto Cruz-Hernández ◽  
Eusebio Juaristi

A few years ago, the synthesis of chiral phosphoric acids supported on chiral BINOL frameworks was accomplished by T. Akiyama and M. Terada. Subsequent relevant applications demonstrated the importance of chiral phosphoric acids as privileged chiral inducers in asymmetric organocatalysis. In the present report we discuss the development of novel chiral phosphorodiamidic acids derived from C2-symmetric trans-1,2-diaminocyclohexane aliphatic frameworks. The preparation of the new chiral Brønsted acids, based on the intermediacy of a 1,3,2-diheterophospholan-2-oxide moiety, turned out to be challenging since several plausible synthetic methodologies proved to be ineffective. Furthermore, the five membered heterocyclic moiety turned out to be easily hydrolyzed when exposed to nucleophilic alcohols or water. Complementary to the successful multistep synthesis reported here, it was possible to obtain crystals of the key precursor of the desired phosphorodiamidic acid, which proved suitable for X-ray diffraction analysis and hence to establish important conformational characteristics of the novel heterocycle.


Author(s):  
Arianna Sinibaldi ◽  
Francesca Della Penna ◽  
Marco Ponzetti ◽  
Francesco Fini ◽  
Silvia Marchesan ◽  
...  

Author(s):  
Arianna Sinibaldi ◽  
Francesca Della Penna ◽  
Marco Ponzetti ◽  
Francesco Fini ◽  
Silvia Marchesan ◽  
...  

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