Mechanistic Investigation of DBU-Based Ionic Liquids for Aza-Michael Reaction: Mass Spectrometry and DFT Studies of Catalyst Role

• Autor(a) principal: Cândido,Augusto A.
• Data de Publicação: 2020
• Outros Autores: Rozada,Thiago C., Rozada,Andrew M. F., Souza,João R. B., Pilau,Eduardo J., Rosa,Fernanda A., Basso,Ernani A., Gauze,Gisele F.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Journal of the Brazilian Chemical Society (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532020000901796
• topic: conjugate addition; aromatic amines; reaction mechanism; theoretical calculations; ESI-MS studies

1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU)-based ionic liquids (ILs) has exhibited a high catalytic activity in the aza-Michael reactions compared to conventional catalysts and with imidazole-based ILs. In the present work DBU-based ILs showed high catalytic potential for aza-Michael addition of aromatic amines to 2-cyclohexen-1-one under solvent-free condition. Electrospray ionization-mass spectrometry (ESI-MS) and density functional theory studies have been carried out to provide an effective activation mode of DBU-based ILs in aza-Michael addition. Our results show that both the presence of the acid hydrogen in the IL and the ability of the anion to carry out a hydrogen bond with the −NH2 group of the arylamine are fundamental for the reaction catalysis. The catalytic model proposed can be used for the rational development of new ILs with excellent catalytic properties.