Novel Brønsted acidic ionic liquids catalyzed one-pot reaction of highly green regioselective thiocyanation of N-containing aromatic and heteroaromatic compounds at room temperature
In this method, a novel Brønsted acidic ionic liquid silica-supported pyridinium sulfonic acid thiocyanate {SiO2@[Pyridine-SO3H]SCN} and sulfonic acid-functionalized pyridinium chloride {[PSA]Cl} were easily synthesized and characterized. In the first method, {SiO2@[Pyridine-SO3H]SCN as a novel and environmentally friendly catalyst with one acidic functional group and one thiocyanation agent group was efficiently used for the synthesis of aryl and heteroaryl thiocyanates via the condensation of anilines, indoles, pyrroles, and their derivatives in the presence of H2O2 as a green oxidant in EtOH:H2O (1:1) at room temperature. In the second method, {[PSA]Cl} as a new ionic liquid and environmentally friendly catalyst with one acidic functional group was used for the simple and efficient synthesis of aryl and heteroaryl thiocyanates via the condensation of anilines, indoles, pyrroles, and their derivatives with NH4SCN in the presence of H2O2 as a green oxidant in EtOH:H2O (1:1) at room temperature. A simple experimental procedure, clean reaction profile, use of an inexpensive catalyst, and recyclability of the catalyst are some of the advantages of the procedure. Also, one of the advantages of the first method is the non-usage of NH4SCN or KSCN in the reaction.
