Chiral Bifunctional Thiosquaramides as Organocatalysts in the Synthesis of Enantioenriched 3,3‐Disubstituted Oxindoles

Rodríguez‐Ferrer, Patricia; Naharro, Daniel; Maestro, A.; Andrés, José M.; Pedrosa, Rafaël

doi:10.1002/ejoc.201901327

Cited by 7 publications

(4 citation statements)

References 63 publications

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“… [213] As shown in Scheme 56 for the thiosquaramide 127 , if CH 2 Cl 2 is employed instead of MeOH, the product precipitation does not occur and a column chromatography is necessary, causing an increase in the E factor (1054). [214] …”

Section: Hydrogen Bond Catalystsmentioning

confidence: 99%

“…Independently from the structure complexity, the squaramide can be easily purified through precipitation employing MeOH as solvent ( E factor 216; Scheme 56). [213] As shown in Scheme 56 for the thiosquaramide 127 , if CH 2 Cl 2 is employed instead of MeOH, the product precipitation does not occur and a column chromatography is necessary, causing an increase in the E factor (1054) [214] …”

Section: Hydrogen Bond Catalystsmentioning

confidence: 99%

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Green Chemistry Meets Asymmetric Organocatalysis: A Critical Overview on Catalysts Synthesis

2021

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Can green chemistry be the right reading key to let organocatalyst design take a step forward towards sustainable catalysis? What if the intriguing chemistry promoted by more engineered organocatalysts was carried on by using renewable and naturally occurring molecular scaffolds, or at least synthetic catalysts more respectful towards the principles of green chemistry? Within the frame of these questions, this Review will tackle the most commonly occurring organic chiral catalysts from the perspective of their synthesis rather than their employment in chemical methodologies or processes. A classification of the catalyst scaffolds based on their E factor will be provided, and the global E factor (E G factor) will be proposed as a new green chemistry metric to consider, also, the synthetic route to the catalyst within a given organocatalytic process.

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Section: Hydrogen Bond Catalystsmentioning

confidence: 99%

Section: Hydrogen Bond Catalystsmentioning

confidence: 99%

Green Chemistry Meets Asymmetric Organocatalysis: A Critical Overview on Catalysts Synthesis

2021

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“…Molecules 2023, 28 Reagents and conditions: 2-naphthol (0.15 mmol, 3 eq. ), N-tosylimine (0.05 mmol, 1 eq.…”

Section: Scheme 2 Proposed Dual Activation For the Thiourea And Thios...mentioning

confidence: 99%

“…Moreover, the presence of a thiourea/thiosquaramide bridge and strongly acidic protons leads to the formation of strong hydrogen bonds and activation of the substrate. While bifunctional chiral thioureas have been widely used in asymmetric synthesis [22][23][24], including the Betti reaction, bifunctional chiral thiosquaramides were used only in Michael addition [25][26][27][28][29], asymmetric Michael-Henry tandem reaction [30], and the addition of lawsone to β,γ-unsaturated α-keto ester [31].…”

Section: Introductionmentioning

confidence: 99%

Development of Bifunctional Chiral Thioureas and Thiosquaramides in the Synthesis of Betti Bases

Malinowska,

Zawisza

2023

Molecules

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Bifunctional thioureas and, for the first time, bifunctional thiosquaramides as organocatalysts were used in the asymmetric Betti reaction involving 1-, 2-naphthols and hydroxyquinoline with N-tosylimine and ketimine. The described methodology affords direct access to chiral aminoarylnaphthols in excellent yield (up to 98%) with high enantioselectivity (up to 80% ee) and enantioenriched 3-amino-2-oxindoles (up to 78% yield, up to 98% ee).

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First Use of Thiosquaramides as Polymerization Catalysts: Controlled ROP of Lactide Implicating Key Secondary Interactions for Optimal Performance

Printz,

Ryzhakov,

Gourlaouen

et al. 2023

ChemCatChem

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We herein report the first use of thiosquaramides as polymerization catalysts, which are shown to be effective for the controlled ROP of lactide in the presence of an alcohol source and NEt3. Comparison of their catalytic performances with the less acidic squaramides are also discussed. The observed catalytic activity of variously N‐substituted thiosquaramides suggest that a balanced NH Brønsted acidity is required for optimal performance. Most interestingly and rather unexpectedly, DFT‐supported calculations on thiosquaramide‐mediated lactide ROP catalysis suggest that secondary interactions between the thiosquaramide N‐substituents and the incoming lactide (presently of type C‐H…p‐arene) are crucial for catalytic activity. Though this type of interactions is quite common in organo‐catalysis, it has rarely been evidenced to play a key role in the area of organo‐catalyzed polymerizations. Such catalyst substituents/substrate interactions may well play a significant role in the catalytic performances of various other systems.

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Chiral Bifunctional Thiosquaramides as Organocatalysts in the Synthesis of Enantioenriched 3,3‐Disubstituted Oxindoles

Cited by 7 publications

References 63 publications

Green Chemistry Meets Asymmetric Organocatalysis: A Critical Overview on Catalysts Synthesis

Green Chemistry Meets Asymmetric Organocatalysis: A Critical Overview on Catalysts Synthesis

Development of Bifunctional Chiral Thioureas and Thiosquaramides in the Synthesis of Betti Bases

First Use of Thiosquaramides as Polymerization Catalysts: Controlled ROP of Lactide Implicating Key Secondary Interactions for Optimal Performance

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