Isolable CO2 Adducts of Polarized Alkenes: High Thermal Stability and Catalytic Activity for CO2 Chemical Transformation

Graphitic Carbon Nitride as Photocatalyst for the Direct Formylation of Anilines

The use of graphitic carbon nitride (g-CN) for the photocatalytic radical formylation of anilines, which represents a more sustainable and attractive alternative to the currently used approaches, is reported herein. Our operationally simple method occurs under mild conditions, employing air as an oxidant. In particular, the chemistry is driven by the ability of g-CN to reach an electronically excited state upon visible-light absorption, which has a suitable potential energy to trigger the formation of reactive α-amino radical species from anilines. Mechanistic investigations also proved the key role of the g-CN to form reactive superoxide radicals from O2 via single electron transfer. Importantly, this photocatalytic transformation provides a variety of functionalized formamides (15 examples, up to 89 % yield).

Exovinylene Cyclic Carbonates: Multifaceted CO2 -Based Building Blocks for Modern Chemistry and Polymer Science

Carbon dioxide is a renewable, inexhaustible, and cheap alternative to fossil resources for the production of fine chemicals and plastics. It can notably be converted into exovinylene cyclic carbonates, unique synthons gaining momentum for the preparation of an impressive range of important organic molecules and functional polymers, in reactions proceeding with 100 % atom economy under mild operating conditions in most cases. This Review summarizes the recent advances in their synthesis with particular attention on describing the catalysts needed for their preparation and discussing the unique reactivity of these CO₂ -based heterocycles for the construction of diverse organic building blocks and (functional) polymers. We also discuss the challenges and the future perspectives in the field.

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.

Facile synthesis, structure and properties of CO2-sourced poly(thioether-co-carbonate)s containing acetyl pendants via thio-ene click polymerization

Synthetic transformation of CO2 into di- and trivinyl carbonates allows for photo-initiated thio-ene polymerization leading to sequence controlled poly(thioether-carbonate)s.

Access to 1,3-oxazine-2,4-diones/1,3-thiazine-2,4-diones via organocatalytic CO2/COS incorporation into allenamides

Organocatalyzed [4 + 2] annulation of CO₂/COS with allenamides is firstly reported to synthesize 1,3-oxazine-2,4-diones and 1,3-thiazine-2,4-diones in moderate to excellent yields under mild reaction conditions. The catalytic potential of a series of Lewis base CO₂ and COS adducts are particularly noted for this process, which features high regio- and chemo-selectivity, step-economy, facile scalability, and easy product derivatization. This study offers the potential for the application of organocatalytic systems for CO₂ and COS chemical transformation.

Synthesis, properties & applications of N-heterocyclic olefins in catalysis

N-Heterocyclic olefins (NHOs), a recently (re-)discovered type of electron-rich, polar alkene, are comprehensively presented. Along with synthetic aspects and chemical properties, special emphasis is put on the multi-faceted impact NHOs already have had on catalysis. This is discussed along the lines of small molecule organocatalysis, organo- and metal-assisted polymerization and of the understanding and application of NHO-ligated organometallic complexes. Highlighted are the strong basicity of NHOs ("superbases"), their high nucleophilicity and the design principles to tailor NHO (organo-)catalysts. It is demonstrated that NHOs can complement, and in many cases out-perform, the much better established N-heterocyclic carbene-based systems. Examples include among others CO₂-sequestration, the polymerization of lactones and epoxides or the transfer hydrogenation of carbonyls. Further, the unique ability to selectively address basic or nucleophilic reaction pathways via NHO-mediation is detailed, as is the bonding situation in NHO-metal complexes and the ability of the olefin to act as an electronically flexible ligand.