Chameleonic reactivity of α-amino nitrile-derived ureas. Synthesis of highly functionalized imidazolidin-2-one and imidazolidine-2,4-dione derivatives

The potential of α-amino nitrile-derived ureas for the synthesis of imidazolidin-2-one derivatives has been studied in the context of a medicinal chemistry project focused on the search of antagonists of the thrombin receptor PAR1. In this study α-amino nitrile-derived ureas have shown chameleonic reactivity. Thus, under neutral, basic or mild acid media they cyclize to 4-iminoimidazolidin-2-one derivatives, which tautomerize to 4-amino-2,3-dihydro-1H-imidazol-2-ones. This tautomerism triggers epimerization at the C5 of the imidazolidine ring, as well as its oxidation. However, they give stable highly functionalized hydantoin derivatives under strong acid media, by a no-epimerizing two-step hydrolysis. [Display omitted]