Catalytic Enantioselective Decarboxylative Aldol Reactions of Malonic Acid Half Thio(oxy)ester and β‐Ketoacids

Chowdhury, Raghunath; Dubey, Mr.Akhil K.; Waser, Mario

doi:10.1002/ejoc.202200146

Cited by 5 publications

(1 citation statement)

References 60 publications

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“…[10] Higher acidity of the α-proton of thioester than in analogous oxoesters [21] allows for a gentle generation of enolate. That feature has been widely employed in asymmetric catalytic reactions of malonic acid half thioesters (MAHTs) and oxoesters (MAHOs) as ester enolate equivalents reactions [22][23][24][25] and, as an even more distinct example, applied in nature. [26][27][28] Notably, the first step in the metabolism of fatty acids involves deprotonation of the Cα-H hydrogen atom, and thus, the thioesters offer greater reactivity in comparison to esters.…”

Section: Introductionmentioning

confidence: 99%

Mechanochemical Assisted Chemoselective and Stereoselective Hydrogen‐Bonding Catalyzed Addition of Dithiomalonates to Enones

et al. 2023

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Abstract. Dithiomalonates proved to be active nucleophiles in the stereoselective additions to chalcones, dienones, and en‐ynones affording the desired Michael adducts with good to high yields and enantioselectivities. In contrast, the analogous dibenzyl malonate remained inactive. Bifunctional Cinchona squaramides secured the effective chirality transfer and the selectivity towards Michael adducts of various bisthiomalonates following the soft enolization approach. The thioester’s nature impacted the reactivity and stability of the reactants or products. While the reactions performed in solution led to the products, the required time along with byproducts formation such as sulfa‐Michael adducts, limiting the applicability of reactive dithioesters. On the contrary, reactions performed under solvent‐free, ball milling conditions furnished adducts with essentially shorter time, with subtly or no byproduct generation. Therefore, the mechanochemical approach revealed to be an effective tool for supporting the hardly effective reactions under standard solution conditions. Detailed KS‐DFT studies supported the experimental observations shedding more light on the intricate active nucleophile formation, and different chemical reaction pathways, as well as indicating the crucial transitions state governing the observed stereoselectivities

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Section: Introductionmentioning

confidence: 99%

Mechanochemical Assisted Chemoselective and Stereoselective Hydrogen‐Bonding Catalyzed Addition of Dithiomalonates to Enones

et al. 2023

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Synthesis of (E)‐α,β‐Unsaturated Thioesters from Malonic Acid Half Thioesters and Aldehydes

2023

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A decarboxylative condensation of malonic acid half thioesters (MAHTs) with aldehydes catalyzed by benzylammonium trifluoroacetate has been developed for the synthesis of (E)‐α,β‐unsaturated thioesters. The reaction of aromatic aldehydes and sterically non‐demanding aliphatic aldehydes proceeded smoothly at room temperature in DMF in a stereo‐ and regioselective manner. Besides the unsubstituted malonate, 2‐fluoro‐ and 2‐methylmalonates could be employed as a nucleophile. Use of the present catalyst could avoid nonproductive protiodecarboxylation of MAHTs.

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Organocatalytic Stereoselective Decarboxylative Addition of α‐Amido Malonic Acid Half Oxyesters to Isatins

Fujita,

Kumazawa,

Yokoi

et al. 2024

Adv Synth Catal

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The stereoselective reaction of α‐amido‐substituted malonic acid half oxyesters (amido‐MAHOs) with isatins was developed. A cinchona alkaloid thiourea catalyst gave products bearing a tetrasubstituted stereogenic centre in high yields with high diastereo‐ and enantioselectivities (75‐99% yield, 83:17‐97:3 dr, 92:8‐99:1 er). The obtained products can be converted into some chiral compounds without loss of enantiopurity. Density functional theory (DFT) calculations were conducted to clarify the origin of stereoselectivities, and revealed that the first centre is set in the decarboxylation, the second in the protonation.

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Catalytic Enantioselective Decarboxylative Aldol Reactions of Malonic Acid Half Thio(oxy)ester and β‐Ketoacids

Cited by 5 publications

References 60 publications

Mechanochemical Assisted Chemoselective and Stereoselective Hydrogen‐Bonding Catalyzed Addition of Dithiomalonates to Enones

Mechanochemical Assisted Chemoselective and Stereoselective Hydrogen‐Bonding Catalyzed Addition of Dithiomalonates to Enones

Synthesis of (E)‐α,β‐Unsaturated Thioesters from Malonic Acid Half Thioesters and Aldehydes

Organocatalytic Stereoselective Decarboxylative Addition of α‐Amido Malonic Acid Half Oxyesters to Isatins

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