title: An efficient one-pot two catalyst system in the construction of 2-substituted benzimidazoles: synthesis of benzimidazo[1,2-c]quinazolines.
abstract: The benzimidazole core is a common moiety in a large number of natural products and pharmacologically active small molecules. The synthesis of novel benzimidazole derivatives remains a main focus in medicinal research. In continuation of the efforts towards Ce(III) catalysts for organic transformations, we observed for the first time the activity of the iodide ion and copper cation in activating CeCl3·7H2O in the selective formation of prototypical 2-substituted benzimidazoles. The one-pot CeCl3·7H2O-CuI catalytic system procedure includes the cyclo-dehydrogenation of aniline Schiff's bases, generated in situ from the condensation of 1,2-phenylenediamine and aldehydes, followed by the oxidation with iodine, which works as a hydrogen sponge. Mild reaction conditions, good to excellent yields, and clean reactions make the procedure a useful contribution to the synthesis of biologically active fused heterocycles containing benzimidazoquinazolines.
authors.affiliation: School of Science and Technology, Chemistry Division, University of Camerino, via S. Agostino 1, I-62032 Camerino (MC), Italy. enrico.marcantoni@unicam.it.
authors.forename: Cristina
authors.initials: C
authors.lastname: Cimarelli
authors.forename: Matteo
authors.initials: M
authors.lastname: Di Nicola
authors.forename: Simone
authors.initials: S
authors.lastname: Diomedi
authors.forename: Riccardo
authors.initials: R
authors.lastname: Giovannini
authors.forename: Dieter
authors.initials: D
authors.lastname: Hamprecht
authors.forename: Roberta
authors.initials: R
authors.lastname: Properzi
authors.forename: Federico
authors.initials: F
authors.lastname: Sorana
authors.forename: Enrico
authors.initials: E
authors.lastname: Marcantoni
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry; D001562:Benzimidazoles / Q000737:chemistry*; D002384:Catalysis; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D015394:Molecular Structure; D011799:Quinazolines / Q000138:chemical synthesis* / Q000737:chemistry; D012545:Schiff Bases / Q000737:chemistry
chemical_list: D000814:Aniline Compounds; D001562:Benzimidazoles; D011799:Quinazolines; D012545:Schiff Bases; C031000:benzimidazole; C023650:aniline