One-pot access to 11-methyl-6H-indolo[2,3-b]quinolines via iodine-mediated annulation of indoles with 2-vinylanilines and evaluation of their biological activities

A simple, straightforward and efficient method for the synthesis of a series of 11-methyl-6H-indolo[2,3-b]quinolines bearing different substituents on the indole and quinoline rings is described. The method involved an annulation reaction of indoles with 2-vinylanilines in the presence of iodine through a cascade intermolecular nucleophilic substitution and intramolecular cyclization in one pot. This process does not require any pre-functionalization procedures for the new C–C and C–N bond formation and provides the desired products in moderate to good yields. Additionally, these tetracyclic compounds were evaluated for their cytotoxicity and antiviral activity against viruses EV71 and CVB3. The preliminary results showed that some of them exhibited excellent antiviral effects on EV71 and CVB3, along with the ability to effectively inhibit virus-induced cytopathic effects and reduce viral progeny yields.