The key nucleophile was found to be neither an enamine nor an enol, but an enolate in the direct Michael reaction of α,β-unsaturated aldehydes and non-activated ketones catalyzed by two amine catalysts namely diphenylprolinol silyl ether and pyrrolidine. This is a rare example of an enolate from a ketone serving as a key intermediate in the asymmetric organocatalytic reaction involving secondary amine catalysts because the ketone enolates are generally generated using a strong base, and the enamine is a common nucleophile in this type of reaction.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8162273 | PMC |
| http://dx.doi.org/10.1039/d0sc03359f | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
A critical appraisal of advances in integrated CO capture and electrochemical conversion.
Chem Sci
January 2025
J. Mike Walker '66 Department of Mechanical Engineering, Texas A&M University College Station TX 77843 USA
This perspective work examines the current advancements in integrated CO capture and electrochemical conversion technologies, comparing the emerging methods of (1) electrochemical reactive capture (eRCC) though amine- and (bi)carbonate-mediated processes and (2) direct (flue gas) adsorptive capture and conversion (ACC) with the conventional approach of sequential carbon capture and conversion (SCCC). We initially identified and discussed a range of cell-level technological bottlenecks inherent to eRCC and ACC including, but not limited to, mass transport limitations of reactive species, limitation of dimerization, impurity effects, inadequate generation of CO to sustain industrially relevant current densities, and catalyst instabilities with respect to some eRCC electrolytes, amongst others. We followed this with stepwise perspectives on whether these are considered intrinsic challenges of the technologies - otherwise recommendations were disclosed where appropriate.
View Article and Find Full Text PDFResearch on transition metals for the multicomponent synthesis of benzo-fused γ-lactams.
RSC Adv
January 2025
Department of Organic Chemistry, Faculty of Chemistry Urmia University Urmia Iran.
Benzo-fused γ-lactams are fundamental in medicinal chemistry, acting as essential elements for various therapeutic agents due to their structural adaptability and capability to enhance biological activity. In their synthesis, transition metals play a pivotal role as catalysts, offering more efficient alternatives to traditional methods by facilitating C-N bond formation through mechanisms like intramolecular coupling. Recent advances have especially spotlighted transition-metal-catalyzed C-H amination reactions for directly converting C(sp)-H to C(sp)-N bonds, streamlining the creation of these compounds.
View Article and Find Full Text PDFImine Synthesis by Engineered d-Amino Acid Oxidase from Porcine Kidney.
ACS Omega
January 2025
Biotechnology Research Center and Department of Biotechnology, Toyama Prefectural University, 5180 Kurokawa, Imizu, Toyama 939-0398, Japan.
Various symmetric and asymmetric imines were synthesized using the novel amine oxidase, obtained as variants of d-amino acid oxidase (pkDAO) from porcine kidney (Y228L/R283G) and (I230A/R283G). Active primary imines produced as intermediates in the oxidation of methylbenzylamine (MBA) derivatives were trapped by aliphatic, aromatic amines and diamines as nucleophiles forming new imines. ()-Fluoro-MBA was the best substrate for symmetric imine synthesis, providing almost stoichiometric conversion (100 mM) and achieving nearly 100% yield.
View Article and Find Full Text PDFNovel Catalyst-Free Synthesis of Some 3-Alkylaminoquinoxaline-2(1)-thiones and 3-Alkyloxyquinoxaline-2(1)-thiones in Ethanol.
ACS Omega
January 2025
School of Chemistry, University of Southampton, Southampton SO17 1BJ, United Kingdom.
Seventeen 3-alkylaminoquinoxaline-2(1)-thiones and 3-alkyloxyquinoxaline-2(1)-thiones were prepared by a novel thionation protocol from the readily available quinoxaline-2,3-dione in excellent overall yields. This protocol starts with the chlorination of dione using thionyl chloride to give 2,3-dichloroquinoxaline followed by the reaction with equimolar amounts of -nucleophiles (primary amines and secondary amines) or -nucleophiles (phenols and alcohols) to principally afford 2-alkanamino-3-chloroquinoxalines or 2-alkyloxy-3-chloroquinoxalines, respectively. The chloroquinoxalines reacted with the thionation reagent -cyclohexyl dithiocarbamate cyclohexyl ammonium salt in ethanol under reflux to principally give the corresponding quinoxalin-2-yl cyclohexylcarbamodithioate that finally rearranges to give the corresponding thiones in 76-93% overall yields.
View Article and Find Full Text PDFA double-chain based metallomicellar catalyst for aerobic oxidative synthesis of benzimidazoles in water.
Dalton Trans
January 2025
Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India.
The oxomolybdenum complexes Mo1, Mo2 and Mo3, which share a common ONO donor ligand backbone but differ in their peripheral substituents, were explored to study their reactivity in organic transformations in water. The ligand backbones of Mo1 and Mo2 were covalently linked to a methyl group and a single hydrophobic -hexadecyl chain an ether linkage, respectively. The complex Mo3 was found to possess two -hexadecyl chains attached to the ligand backbone a common amine-N.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!