title: A Van Leusen deprotection-cyclization strategy as a fast entry into two imidazoquinoxaline families.
abstract: A concise synthesis of two pharmacologically relevant classes of molecules possessing the imidazoquinoxaline core is reported. The protocol involves use of 1,2-phenylenediamines and glyoxylic acid derivatives, namely ethyl glyoxylate or benzylglyoxamide, along with tosylmethylisocyanides in a microwave-assisted Van Leusen three-component condensation. Subsequent unmasking (Boc removal) of an internal amino-nucleophile promotes deprotection and cyclization that take place either spontaneously in a one-pot fashion to give8or upon acidic treatment under microwave irradiation after isolation of the imidazole intermediate to give11. Of note, a tricyclic framework is hence assembled by means of a rapid and straightforward method with a high bond-forming efficiency.
authors.affiliation: Department of Pharmacology and Toxicology, College of Pharmacy, BIO5 Oro Valley, The University of Arizona, 1580 E. Hanley Blvd., Oro Valley, Arizona 85737, USA.
authors.forename: Fabio
authors.initials: F
authors.lastname: De Moliner
authors.forename: Christopher
authors.initials: C
authors.lastname: Hulme
keywords: Heterocycles; Imidazoquinoxalines; Multicomponent reactions; TOSMICs