CO2 Adducts of Carbodicarbenes: Robust and Versatile Organocatalysts for Chemical Transformation of Carbon Dioxide into Heterocyclic Compounds

• Published in: ChemCatChem Vol. 10; no. 12; pp. 2686 - 2692
• Main Authors: Liu, An‐Hua, Dang, Ya‐Li, Zhou, Hui, Zhang, Jin‐Ju, Lu, Xiao‐Bing
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 21-06-2018
• Subjects: Adducts; Alcohols; Basicity; carbodicarbene; Carbon dioxide; carbon dioxide fixation; Carbonates; cyclization; Decarboxylation; Fourier transforms; Functional groups; Heterocyclic compounds; homogeneous catalysis; Mass spectrometry; NMR spectroscopy; Organic chemistry; Substrates; synthetic methods; Thermogravimetric analysis
• ISSN: 1867-3880; 1867-3899
• DOI: 10.1002/cctc.201800148

Four CO2 adducts of carbodicarbenes (CDCs) were first synthesized and structurally characterized by means of NMR spectroscopy, high‐resolution mass spectrometry, and FTIR spectroscopy. The introduction of 13C‐labelled CO2 confirmed the formation of the corresponding carboxylated species. Thermogravimetric analysis (TGA) provided detailed information on their thermal decarboxylation processes. The novel CDC–CO2 adducts were subsequently applied as robust and versatile organocatalysts for the carboxylative cyclization of CO2 with aziridines, epoxides, or propargylic alcohols, affording 2‐oxazolidinones and cyclic carbonates in good to excellent yields (51–99 %) and high functional group tolerance. TGA results together with control experiments indicate that the in situ formed free CDC by decarboxylation of the corresponding CDC–CO2 adducts plays the key role to activate the substrates by its strong Lewis basicity.
CO2 catching: Various CO2 adducts of carbodicarbenes (CDC) are synthesized and employed as versatile organocatalysts for the cyclization of CO2 with aziridines, epoxides, or propargylic alcohols, affording 2‐oxazolidinones and cyclic carbonates in good to excellent yields. The decarboxylation of CDC–CO2 is crucial for the cyclization reaction.