Aqueous CO2 fixation: construction of pyridine skeletons in cooperation with ammonium cations

• Published in: Green chemistry : an international journal and green chemistry resource : GC Vol. 23; no. 20; pp. 7950 - 7955
• Main Authors: Xiang, Shiqun, Fan, Weibin, Zhang, Wei, Li, Yinghua, Guo, Shiwei, Huang, Deguang
• Format: Journal Article
• Language: English
• Published: CAMBRIDGE Royal Soc Chemistry 18.10.2021; Royal Society of Chemistry
• Subjects: Ammonium; Aqueous solutions; Carbon dioxide; Carbon dioxide fixation; Carbon sources; Cations; Chemistry; Chemistry, Multidisciplinary; Cycloaddition; Green & Sustainable Science & Technology; Green chemistry; Ketones; Materials selection; Monoethanolamine (MEA); Optoelectronics; Photosensitivity; Physical Sciences; Pyridines; Reaction mechanisms; Science & Technology; Science & Technology - Other Topics; Synthesis; FORMYLATION; METHYLATION; C1 BUILDING-BLOCK; HYDROGENATION; REDUCTION; ELECTROREDUCTION; AMINES; CARBON-DIOXIDE; CYCLIZATION; CATALYSTS
• ISSN: 1463-9262; 1463-9270
• DOI: 10.1039/d1gc02303a

A simple and green method is explored for the synthesis of fused pyridines by [2 + 2 + 1 + 1] the cycloaddition of ketones with an ammonium cation under a CO2 atmosphere. The reactions employed ammonium cation as a nitrogen source and CO2 gas as a carbon source in an aqueous solution. Monoethanolamine (MEA) was used as an additive to increase the solubility of CO2 in an aqueous solution. The scope and versatility of the method are demonstrated with 38 examples. Products are found to be photosensitive and show potential applications as organic optoelectronic materials. A selectfluor-promoted reaction mechanism is proposed based on the experimental studies. Our work is superior as it is a metal-free system, uses CO2 as a carbon source and MEA as an additive in aqueous synthesis.