Transformation of Atmospheric CO₂ Catalyzed by Protic Ionic Liquids: Efficient Synthesis of 2‐Oxazolidinones

Abstract

Protic ionic liquids (PILs), such as 1, 8-diazabicyclo-[5.4.0]-7-undecenium 2-methylimidazolide [DBUH][MIm], can catalyze the reaction of atmospheric CO 2 with ab road range of propargylic amines to form the corresponding 2oxazolidinones.The products are formed in high yields under mild, metal-free conditions.The cheaper and greener PILs can be easily recycled and reused at least five times without ad ecrease in the catalytic activity and selectivity.Areaction mechanism was proposed on the basis of adetailed DFT study which indicates that both the cation and anion of the PIL play key synergistic roles in accelerating the reaction.

Transition Metal‐Free CO2 Fixation into New Carbon–Carbon Bonds

“…[2] However,t hese classical methods are limited to highly reactive substrates and/or harsh reaction conditions. Thus, they can be regarded as functionalization of CO 2 to producea dded-value chemicals, such as carbonates, [6] oxazolidinones, [7] and quinazolidine-2,4diones. [3] The beginning of the twenty-first century has seen the use of small organic molecules as ap owerful, complementary strategy to metal-based catalysis.…”

Efficient and Recyclable Cobalt(II)/Ionic Liquid Catalytic System for CO2 Conversion to Prepare 2‐Oxazolinones at Atmospheric Pressure

“…After that, the reusability of the catalyst was investigated, which was rarely mentioned in previous work [6d,6p,6v,6x,7a] . 1a was chosen as the model substrate to investigate the recyclability of the catalytic system, in which CoBr 2 and [EEIM][OAc] were reused after extracting 2a with hexane and removing the residual hexane under vacuum.…”

“…In detail, tunable structures of ILs make them easy to dissolve the substrates, benefiting homogeneous catalysis; meanwhile, their high polarity is beneficial to recover from products with the assistance of low‐polar solvents. Recently, Han's group reported ILs as catalysts can promote the reaction of propargylic amines with CO 2 efficiently, in which the ILs are reusable [7a,7e]. Based on all of these, we questioned whether the introduction of ILs into transition‐metal catalysts might give them reusability while maintaining their high efficiency.…”

“…Among multifarious CO 2 transformation, the carboxylative cyclization of propargylic amines with CO 2 represents a typical example of using CO 2 as a raw material to synthesize valuable 2‐oxazolidones, which are common substructures in pharmaceuticals and found in asymmetric catalysis as chiral auxiliaries . Methodologies by employing transition metals and organocatalysts for this transformation have been developed. Notably, Yamada's group achieved this transformation under mild conditions, in particular low CO 2 pressure, by using silver(I) salts as catalysts [6h,6o].…”

Integrated CO2 capture-fixation chemistry via interfacial ionic liquid catalyst in laminar gas/liquid flow

“…The cation and anion pair has a synergic effect for the catalysis1920. It is noted that an appropriate solvent must be chosen to assure a CA that is high enough for maintaining a stable laminar flow over the DBU-ILs immobilized SiNWs.…”