Fast and efficient regioselective synthesis of a novel eight membered ring system, 5H-benzo[f]pyrimido[4,5-b][1,5]oxazocine

An efficient two-steps strategy for the regioselective synthesis of the benzo[f]pyrimido[4,5-b][1,5]oxazocine as a novel tricyclic system has been developed via inter- and intramolecular heterocyclization of 2,4-dichloro-5-(chloromethyl)-6-methylpyrimidine and 2-aminobenzylalcohol in room temperature and short reaction times under mild conditions, followed amination with some secondary amines. 2D-NOESY and HMBC NMR spectroscopy was performed to gain the true regioisomer of the reaction, as well. Graphic abstract: