An Expeditious and Greener Synthesis of 2-Aminoimidazoles in Deep Eutectic Solvents
Martina Capua,
Serena Perrone,
Filippo Maria Perna,
Paola Vitale,
Luigino Troisi,
Antonio Salomone,
Vito Capriati
Affiliations
Martina Capua
Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, Università del Salento, Prov.le Lecce-Monteroni, Lecce I-73100, Italy
Serena Perrone
Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, Università del Salento, Prov.le Lecce-Monteroni, Lecce I-73100, Italy
Filippo Maria Perna
Dipartimento di Farmacia-Scienze del Farmaco, Università degli Studi di Bari «Aldo Moro», Consorzio C.I.N.M.P.I.S., Via E. Orabona 4, Bari I-70125, Italy
Paola Vitale
Dipartimento di Farmacia-Scienze del Farmaco, Università degli Studi di Bari «Aldo Moro», Consorzio C.I.N.M.P.I.S., Via E. Orabona 4, Bari I-70125, Italy
Luigino Troisi
Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, Università del Salento, Prov.le Lecce-Monteroni, Lecce I-73100, Italy
Antonio Salomone
Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, Università del Salento, Prov.le Lecce-Monteroni, Lecce I-73100, Italy
Vito Capriati
Dipartimento di Farmacia-Scienze del Farmaco, Università degli Studi di Bari «Aldo Moro», Consorzio C.I.N.M.P.I.S., Via E. Orabona 4, Bari I-70125, Italy
A high-yield one-pot two-step synthesis of 2-aminoimidazoles (2-AI), exploiting an under-air heterocyclodehydration process between α-chloroketones and guanidine derivatives, and using deep eutectic solvents (DESs) as nonconventional, “green” and “innocent” reaction media, has been accomplished successfully. The combination of either glycerol or urea with choline chloride (ChCl) proved to be effective for decreasing the reaction time to about 4–6 h in contrast to the 10–12 h usually required for the same reaction run in toxic and volatile organic solvents and under an argon atmosphere. In addition, the use of the ChCl–urea as a DES also enables the direct isolation of triaryl-substituted 2-AI derivatives by means of a simple work-up procedure consisting in filtration and crystallization, and allows the recycle of the DES mixture. A plausible mechanism highlighting the potential role played by hydrogen bonding catalysis has also been illustrated.