Preparation of new substituted imidazolone derivatives based on 1-(2-oxo-2-phenylethylidene)pyrrolo[3,2,1-ij]quinolin-2-ones

This work demonstrates the possibility of obtaining new biologically active molecules containing a privileged imidazolone fragment by the Brønsted acid-catalyzed reaction of 1,3-dimethylurea with 1-(2-oxo-2-phenylethylidene)pyrrolo[3,2,1-ij]quinolin-2-ones. The presence of an active oxoylidene system in ones makes it possible to introduce these compounds into cyclization reactions with various binucleophilic agents. The choice of such an N,N-binucleophile as 1,3-dimethylurea allowed us to obtain a number of new 1-(oxoimidazolyl)pyrrolo[3,2,1-ij]quinolin2-ones in a process carried out at refl ux in acetonitrile and a tenfold excess of 1,3-dimethylurea via p-toluenesulfonic acid catalysis. It has been found that 1-(oxoimidazolyl)pyrrolo[3,2,1-ij]quinolin-2-ones in solution undergo keto-enol tautomerism. This is evidenced by the duplication of characteristic proton signals and the presence of the hydroxyl group proton signal in the region of 4.95 ppm in the 1 H NMR spectrum of the obtained compounds. Also, based on the experimental data, we have presented a possible reaction mechanism. It is assumed that the reaction proceeds through consistent intermolecular addition of 1,3-dimethylurea to 1-phenacylidenepyrrolo[3,2,1-ij]quinolin-2-ones with intramolecular cyclization, followed by elimination of a water molecule.

pyrrolo[3, 2, 1-ij]quinolin-2-one, imidazol-2-one, 1, 3-dimethylurea