Bifunctional Silver(I) Complex‐Catalyzed CO₂ Conversion at Ambient Conditions: Synthesis of α‐Methylene Cyclic Carbonates and Derivatives

Abstract

The chemical conversion of CO2 at atmospheric pressure and room temperature remains a great challenge. The triphenylphosphine complex of silver(I) carbonate was proved to be a robust bifunctional catalyst for the carboxylative cyclization of propargylic alcohols and CO2 at ambient conditions leading to the formation of α-methylene cyclic carbonates in excellent yields. The unprecedented performance of [(PPh3)2Ag]2CO3 is presumably attributed to the simultaneous activation of CO2 and propargylic alcohol. Moreover, the highly compatible basicity of the catalytic species allows propargylic alcohol to react with CO2 leading to key silver alkylcarbonate intermediates: the bulkier [(Ph3P)2Ag(I)](+) effectively activates the carbon-carbon triple bond and enhances O-nucleophilicity of the alkylcarbonic anion, thereby greatly promoting the intramolecular nucleophilic cyclization. Notably, this catalytic protocol also worked well for the reaction of propargylic alcohols, secondary amines, and CO2 (at atmospheric pressure) to afford β-oxopropylcarbamates.

AgI/TMG‐Promoted Cascade Reaction of Propargyl Alcohols, Carbon Dioxide, and 2‐Aminoethanols to 2‐Oxazolidinones

“…In addition, with furtherm odulating the loading of Ag 2 Oa nd TMG, the molar ratio of 1a and 2a,a nd reaction temperature (entries 12-15), quantitative yields for both products 3a and 4a were obtained (entry 15). In contrast, 5mol %A g 2 Oo r 30 mol %T MG alone exhibited exceedingly low activity under the given conditions (entries 16,17). The effect of the molar ratio of Ag 2 O/TMGo nt he reactiono utcome (entries 15, 18-19 vs. 20) indicates that the in situ formed silver complex with 1:2 molar ratio of Ag 2 O/TMG is the active catalytic species.…”

“…[16] Indeed,s ilver compounds in combination with organic bases, for example, DBU (2,3,4,6,7,8,9,10-octahydropyrimido[1,2-a]azepine) or nitrogencontaining ligands, effectively catalyzed the carboxylative cyclization of propargyl alcohols with CO 2 . [17] Furthermore, N-heterocyclic olefins can also be used as an robust organocatalyst, rendering the reactionp roceed under mild conditions.…”

Silver(I)‐Catalyzed Synthesis of β‐Oxopropylcarbamates from Propargylic Alcohols and CO2 Surrogate: A Gas‐Free Process

“…[21,22] Therefore, we herein expand the potential applicationso ft he silver(I) catalyst system to the two-componentr eaction of propargylic alcohols and PIPC as indicated in Scheme 3. In this protocol, b-oxopropylcarbamates were obtained in 27-60 %i solated yields at ambient conditions.…”

New Coordination Complexes Based on the 2,6-bis[1-(Phenylimino)ethyl] Pyridine Ligand: Effective Catalysts for the Synthesis of Propylene Carbonates from Carbon Dioxide and Epoxides

“…The chemical fixation and conversion of carbon dioxide into valuable chemicals is generally regarded as an excellent method from both the environmental protection and resource utilization standpoints [1,2,3,4,5]. As a naturally abundant, cheap, recyclable, and nontoxic carbon source, carbon dioxide has been involved in various organic reactions, especially the cycloaddition of epoxides with carbon dioxide to produce carbonates [6,7,8,9,10,11]. This reaction is a standard “atom-economy” and “green-chemistry” reaction to produce environmentally-friendly propylene carbonate that is widely utilized as a special solvent in many chemical industries such as liquefied natural gas (LNG), the textile printing industry, lithium batteries, and wood processing [12,13,14,15].…”