| Summary: | A new 2-amino imidazole derivative, 5-(4-chlorophenyl)-<i>N</i>,1-di-o-tolyl-1H-imidazole-2-amine (<b>3</b>), has been synthesized using a green approach. The reaction was conducted in a ChCl (cholinium chloride)/urea eutectic mixture, which is a nature-inspired and environmentally friendly reaction medium. The proposed reaction mechanism involves the preliminary regioselective alkylation of the <i>N</i><sub>sp2</sub> of guanidine (<b>2</b>), followed by an intramolecular condensation between the carbonyl moiety and the secondary <i>N′</i><sub>sp3</sub>. Finally, a tautomerization/aromatization step furnished the final product (<b>3</b>). Notably, 2-amino imidazole (<b>3</b>) could be isolated in high yield (91%), just by filtration from the DES/water mixture and subsequent crystallization; the remaining ChCl/urea could be recycled, after water removal, for four consecutive reactions without any significant drop in the (<b>3</b>) yield. The product has been fully characterized by <sup>1</sup>H, <sup>13</sup>C, 2D <sup>1</sup>H-<sup>13</sup>C HSQC, and 2D <sup>1</sup>H-<sup>13</sup>C HMBC NMR; FT-IR spectroscopy; and EI-MS spectrometry.
|
|---|