Valorization of Carbon Dioxide into Oxazolidinones by Reaction with Aziridines

Protonated Porphyrins: Bifunctional Catalysts for the Metal-Free Synthesis of N-Alkyl-Oxazolidinones

The protonation of commercially available porphyrin ligands yields a class of bifunctional catalysts able to promote the synthesis of N-alkyl oxazolidinones by CO2 cycloaddition to corresponding aziridines. The catalytic system does not require the presence of any Lewis base or additive, and shows interesting features both in terms of cost effectiveness and eco-compatibility. The metal-free methodology is active even with a low catalytic loading of 1 % mol, and the chemical stability of the protonated porphyrin allowed it to be recycled three times without any decrease in performance. In addition, a DFT study was performed in order to suggest how a simple protonated porphyrin can mediate CO2 cycloaddition to aziridines to yield oxazolidinones.

Recent Advances in the Synthesis of Five-Membered Cyclic Carbonates and Carbamates from Allylic or Propargylic Substrates and CO2

The organic carbamates and carbonates are highly desirable compounds that have found a wide range of applications in drug design, medicinal chemistry, material science, and the polymer industry. The development of new catalytic carbonate and carbamate forming reactions, which employ carbon dioxide as a cheap, green, abundant, and easily available reagent, would thus represent an ideal substitution for existing methods. In this review, the advancements in the catalytic conversion of allylic and propargylic alcohols and amines to corresponding five-membered cyclic carbonates and carbamates are summarized. Both the metal- and the organocatalyzed methods are reviewed, as well as the proposed mechanisms and key intermediates of the illustrated carbonate and carbamate forming reactions.

En Route to CO2-Based (a)Cyclic Carbonates and Polycarbonates from Alcohols Substrates by Direct and Indirect Approaches

This review is dedicated to the state-of-the art routes used for the synthesis of CO2-based (a)cyclic carbonates and polycarbonates from alcohol substrates, with an emphasis on their respective main advantages and limitations. The first section reviews the synthesis of organic carbonates such as dialkyl carbonates or cyclic carbonates from the carbonation of alcohols. Many different synthetic strategies have been reported (dehydrative condensation, the alkylation route, the “leaving group” strategy, the carbodiimide route, the protected alcohols route, etc.) with various substrates (mono-alcohols, diols, allyl alcohols, halohydrins, propargylic alcohols, etc.). The second section reviews the formation of polycarbonates via the direct copolymerization of CO2 with diols, as well as the ring-opening polymerization route. Finally, polycondensation processes involving CO2-based dimethyl and diphenyl carbonates with aliphatic and aromatic diols are described.

Conversion of CO2 to epoxides or oxazolidinones enabled by a CuI/CuII-organic framework bearing a tri-functional linker

One mixed-valence Cu–MOF has been synthesized, which could prompt the conversion of CO2 to epoxides and oxazolidinones under mild conditions.

Diethylammonium iodide as catalyst for the metal-free synthesis of 5-aryl-2-oxazolidinones from aziridines and carbon dioxide

The catalytic potential of ammonium halide salts was explored in the coupling reaction of a model aziridine with carbon dioxide, highlighting the superior activity of [NH2Et2]I. Then, working at room temperature, atmospheric CO2 pressure and in the absence of solvent, the [NH2Et2]I-catalyzed synthesis of a series of 5-aryl-2-oxazolidinones was accomplished in good to high yields and excellent selectivity, from 2-aryl-aziridines with N-methyl or N-ethyl groups. NMR studies and DFT calculations outlined the pivotal role of both the diethylammonium cation and the iodide anion. The proposed method represents a convenient choice for obtaining a limited number of valuable molecules for which more complex and more expensive catalytic systems have been reported even in recent years.

Ni-Catalyzed Carboxylation of Aziridines en Route to β-Amino Acids

A Ni-catalyzed reductive carboxylation of N-substituted aziridines with CO₂ at atmospheric pressure is disclosed. The protocol is characterized by its mild conditions, experimental ease, and exquisite chemo- and regioselectivity pattern, thus unlocking a new catalytic blueprint to access β-amino acids, important building blocks with considerable potential as peptidomimetics.

Bypassing the Inertness of Aziridine/CO2 Systems to Access 5-Aryl-2-Oxazolidinones: Catalyst-Free Synthesis Under Ambient Conditions

The development of sustainable synthetic routes to access valuable oxazolidinones via CO₂ fixation is an active research area, and the aziridine/carbon dioxide coupling has aroused a considerable interest. This reaction features a high activation barrier and thus requires a catalytic system, and may present some other critical issues. Here, the straightforward gram-scale synthesis of a series of 5-aryl-2-oxazolidinones was developed at ambient temperature and atmospheric CO₂ pressure, in the absence of any catalyst/co-catalyst. The key to this innovative procedure consists in the direct transfer of the pre-formed amine/CO₂ adduct (carbamate) to common aziridine precursors (dimethylsulfonium salts), replacing the classical sequential addition of amine (intermediate isolation of aziridine) and then CO₂ . The reaction mechanism was investigated by NMR spectroscopy and DFT calculations applied to model cases.

Recent Advances in the Chemistry of Metal Carbamates

Following a related review dating back to 2003, the present review discusses in detail the various synthetic, structural and reactivity aspects of metal species containing one or more carbamato ligands, representing a large family of compounds across all the periodic table. A preliminary overview is provided on the reactivity of carbon dioxide with amines, and emphasis is given to recent findings concerning applications in various fields.

Intertwined chemistry of hydroxyl hydrogen-bond donors, epoxides and isocyanates in the organocatalytic synthesis of oxazolidinones versus isocyanurates: rational catalytic investigation and mechanistic understanding

The efficiency and chemoselectivity of the cycloaddition of isocyanates to epoxides to afford oxazolidinones were investigated using hydroxyl hydrogen-bond donors as organocatalysts.