The straightforward organocatalytic insertion of carbon disulfide (CS) into epoxides using either choline chloride () or tetrabutylammonium chloride (TBACl) is reported, for the first time, under solvent-free (neat) conditions. Fine-tuning of our system allowed us to obtain either dithiocarbonates (DTCs) or trithiocarbonates (TTCs) with high efficiency. Additionally, a mechanistic proposal is presented, supported by experimental evidence, DFT calculations and wavefunction analyses.
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http://dx.doi.org/10.1039/d4cc05154h | DOI Listing |
Chem Commun (Camb)
January 2025
Laboratorio de Química Sintética Sostenible (QuimSinSos), Departamento de Química Orgánica e Inorgánica, (IUQOEM) and ORFEO-CINQA, Facultad de Química, Universidad de Oviedo, E33071 Oviedo, Spain.
The straightforward organocatalytic insertion of carbon disulfide (CS) into epoxides using either choline chloride () or tetrabutylammonium chloride (TBACl) is reported, for the first time, under solvent-free (neat) conditions. Fine-tuning of our system allowed us to obtain either dithiocarbonates (DTCs) or trithiocarbonates (TTCs) with high efficiency. Additionally, a mechanistic proposal is presented, supported by experimental evidence, DFT calculations and wavefunction analyses.
View Article and Find Full Text PDFChem Sci
April 2024
Department of Industrial Chemistry "Toso Montanari", Center for Chemical Catalysis C3 & INSTM RU Bologna V. Gobetti 85 40129 Bologna Italy
Organocatalytic asymmetric synthesis has evolved over the years and continues to attract the interest of many researchers worldwide. Enantiopure noncanonical amino acids (ncAAs) are valuable building blocks in organic synthesis, medicinal chemistry, and chemical biology. They are employed in the elaboration of peptides and proteins with enhanced activities and/or improved properties compared to their natural counterparts, as chiral catalysts, in chiral ligand design, and as chiral building blocks for asymmetric syntheses of complex molecules, including natural products.
View Article and Find Full Text PDFOrg Biomol Chem
November 2023
Bauman Moscow State Technical University, 2nd Baumanskaya ul., 5/1, 105005 Moscow, Russia.
Herein, we propose a novel mechanistic model for NHC-mediated carbonyl umpolung which involves the formation of a carbanionic carbene Breslow intermediate (CCBI). We have demonstrated theoretically that this reactive intermediate can be formed by inserting an aldehyde into the C4-H position of an -aryl-substituted imidazolium-derived NHC the generation of an H-bonded ditopic carbanionic NHC (NHC). Our DFT study on benzoin condensation has revealed that the mechanism of polarity inversion proceeding through the CCBI may be more energetically favorable than the classical mechanism of umpolung that uses the C2 carbene position in NHC.
View Article and Find Full Text PDFChem Sci
January 2023
Advanced Catalysis and Green Manufacturing Collaborative Innovation Center, School of Petrochemical Engineering, Changzhou University Changzhou 213164 China
While asymmetric insertion of metal carbenes into H-X (X = C, N, O, ) bonds has been well-established, asymmetric control over free carbenes is challenging due to the presence of strong background reactions and lack of any anchor for a catalyst interaction. Here we have achieved the first photo-induced metal-free asymmetric H-X bond insertion of this type. With visible light used as a promoter and a chiral phosphoric acid used as a catalyst, α-diazoesters and aryl amines underwent smooth N-H bond insertion to form enantioenriched α-aminoesters with high efficiency and good enantioselectivity under mild conditions.
View Article and Find Full Text PDFChem Commun (Camb)
January 2023
Advanced Catalysis and Green Manufacturing Collaborative Innovation Center, School of Petrochemical Engineering, Changzhou University, Changzhou 213164, China.
Disclosed herein is an efficient organocatalytic formal N-H insertion reaction of arylamines with α-keto sulfoxonium ylides bearing two aryl groups, delivering a broad range of α-tertiary aminoketones with good to excellent yields and enantioselectivities (up to 90% yield and 94% ee). The utilities of this protocol were also demonstrated by facile preparation of enantioenriched 2-amino-1,2-diarylethanol bearing two different aryl groups, a type of important building block lacking efficient access.
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