Facile microwave-assisted synthesis of cyclic amidinium salts.
The cyclization of N,N'-dialkyl or diaryl ethane-1,2-diamines or propane-1,3-diamines with inorganic ammonium salts and orthoesters proceeds briskly under microwave irradiation to afford the corresponding imidazolinium or tetrahydropyrimidinium salts. The transformation is highly versatile and tolerates a wide range of substituents and counterions. It could be scaled from 1 to 50 mmol without any difficulty. Because the workup is equally rapid and straightforward, this experimental procedure provides fast and convenient access to an important class of heterocyclic compounds that have found numerous applications as N-heterocyclic carbene precursors, organocatalysts, and ionic liquids.
Center for Education and Research on Macromolecules, Institut de chimie (B6a), Université de Liège, Sart-Tilman par 4000 Liège, Belgium.
Adila
A
Aidouni
Soufiane
S
Bendahou
Albert
A
Demonceau
Lionel
L
Delaude
D000578:Amidines / Q000138:chemical synthesis*; D003500:Cyclization; D003959:Diamines / Q000737:chemistry; D006571:Heterocyclic Compounds; D008872:Microwaves; D000644:Quaternary Ammonium Compounds; D012492:Salts / Q000138:chemical synthesis
D000578:Amidines; D003959:Diamines; D006571:Heterocyclic Compounds; D000644:Quaternary Ammonium Compounds; D012492:Salts