Prolinethioamides versus Prolinamides in Organocatalyzed Aldol Reactions—A Comparative Study

Gryko, Dorota; Chromiński, Mikołaj; Pielacińska, Dominika J.

doi:10.3390/sym3020265

Cited by 18 publications

(6 citation statements)

References 62 publications

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“…The conversion of amide moiety to the corresponding thioamide [216] increases the acidity of amide and therefore allows the formation of stronger hydrogen bonds. Thioamide 157 (20 mol%) was evaluated in the intermolecular aldol reaction between acetone (52a, 27.2 equiv) and aromatic aldehydes at 4 • C in the presence of TFA (20 mol%) affording the expected compounds 54 in good results (20-86%, 73-94%).…”

Section: Proline Derivatives As Organocatalysts 189mentioning

confidence: 99%

Organocatalyzed Aldol Reactions

Guillena¹

2013

Modern Methods in Stereoselective Aldol Reactions

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The use of catalytic enantioselective methods to perform an aldol reaction provides a direct entry for the synthesis of chiral compounds and is probably the most attractive way to achieve this goal with high control of the chemo-, regio-, diastereo-, and enantioselectivity. The application of biochemical methods based on enzyme aldolases or antibodies, which are discussed in other chapters, avoid the use of preformed enolates or their equivalents for enhancing the global atom efficiency of the process [1] for which the narrow substrate scope is a major drawback. The discovery of methodologies to carry out the enantioselective direct aldol reaction [2] has eluded the production of stoichiometric by-products increasing the substrate scope. This task could be accomplished by using small molecules as catalysts, such as metal complexes (which are covered along this book) and organic molecules, also known as organocatalysts [3]. The growth of this last research area and the direct aldol reaction are closely linked [4], with the report on the use of (S)-proline as catalyst for the intermolecular aldol [5] definitely being the push for the development of the organocatalytic methods as a competitive methodology for the synthesis of chiral compounds.In a strict sense, an organocatalyzed reaction is a process in which all the involved reagents and catalysis are purely organic compounds of low-molecular weight, excluding boron-and silicon-containing derivatives. However, in some cases, the presence of a silyl group only plays a steric role and therefore can also be considered as an organocatalyzed process. Also, if the organocatalyst involved in a reaction is immobilized in a polymer, a dendrimer, or even an inorganic material that serves only as a support to facilitate its recovery [6], it could still be considered as an organocatalyst, although those types of derivatives have been scarcely used in the natural product synthesis and therefore will be excluded from this chapter. Therefore, a comprehensive overview of the direct aldol reaction [7], emphasizing the reactivity, scope, selectivity, and limitations of the methodology and giving several examples of their application to the synthesis of biologically active compounds, is discussed in this chapter.

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Section: Proline Derivatives As Organocatalysts 189mentioning

confidence: 99%

Organocatalyzed Aldol Reactions

Guillena¹

2013

Modern Methods in Stereoselective Aldol Reactions

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“…On performing glycosylation using catalyst 3 d , afforded the product 14 & 15 with comparable yields and selectivity (62–66%, α:β 10:1–11:1). Whereas in case of catalyst 3 e & 3 f , a drastic change in the yield of the product 14 was observed that manifest the importance of substituted NH 2 of catalyst 3 b towards its reactivity [29] …”

Section: Resultsmentioning

confidence: 96%

“…Whereas in case of catalyst 3 e & 3 f, a drastic change in the yield of the product 14 was observed that manifest the importance of substituted NH 2 of catalyst 3 b towards its reactivity. [29] Scheme 4. Synthesis of trehalose-type 1,1'-linked sugars.…”

Section: Resultsmentioning

confidence: 99%

L‐Proline Derived Thioamide Small Organic Molecule for the α‐Stereoselective Synthesis of 2‐Deoxyglycosides

et al. 2023

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L‐Prolinethioamide catalyzes direct stereoselective glycosylation of glycal donors to access 2‐deoxyglycosides under moderate reaction conditions. This proposed glycosylation protocol produced the desired products in up to 88% yield and shows greater tolerance of glycosyl acceptors and a broad substrate scope with better stereoselectivity. This method is also applicable for less nucleophilic acceptors such as phenol. In addition, 1,1′‐linked trehalose‐type analogues can also be accessed through this methodology. Further, mechanistic studies suggest that, in this glycosylation, L‐prolinethioamide operates via Brønsted acid/base catalysis.

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“…Among them, the amide derivatives are a useful class of these types of catalysts. Because they can be synthesized easily, they contain NH group to make hydrogen bond with aldehyde to activate it, and their structures can be modified to change their catalytic activity [7].…”

Section: Introductionmentioning

confidence: 99%

An investigation of chiral diamides as organocatalysts in asymmetric aldol reaction

Yilmaz

Aydoğan

Yolaçan

2022

Journal of Heterocyclic Chem

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Seven novel proline and 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (THIQA) based diamides were synthesized successfully by simple amidation reactions and characterized by their spectral data. Their catalytic activities in asymmetric aldol reaction were performed by the reactions of aliphatic ketones and various aromatic aldehydes. Especially, (S)-N-((S)-1-(morpholinoamino)-1-oxo-3-phenylpropan-2-yl)pyrrolidine-2-carboxamide (9e) showed good catalytic activities in water at room temperature in the presence of benzoic acid cocatalyst. The enantioselectivities were upto 89.6%, the diastereomeric ratios were upto 92/8, and yields were upto 97.3%. This catalyst showed its best catalytic activities in water; this is also an important contribution to green chemistry requirements.

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Prolinethioamides versus Prolinamides in Organocatalyzed Aldol Reactions—A Comparative Study

Cited by 18 publications

References 62 publications

Organocatalyzed Aldol Reactions

Organocatalyzed Aldol Reactions

L‐Proline Derived Thioamide Small Organic Molecule for the α‐Stereoselective Synthesis of 2‐Deoxyglycosides

An investigation of chiral diamides as organocatalysts in asymmetric aldol reaction

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