CAN-mediated new, regioselective one-pot access to bicyclic cationic structures with 2,3-dihydro-1H-pyrazolo[1,2-a]pyrazol-4-ium core

A new, facile, regioselective ceric ammonium nitrate (CAN)-mediated one-pot access to bridgehead hydrazine bicyclic cationic structures with 2,3-dihydro-1H-pyrazolo[1,2-alpyrazol-4-ium cations and [Ce3+(NO3)(6)](3-) anion has been developed. The approach comprises [3+2]-cycloaddition of (2-bromo-2-nitrovinyl)arenes to N,N-cyclic azomethine imines, generated in situ by diaziridine ring opening in 6-Ar-1,5-diazabicyclo[3.1.0]hexanes or by metathesis of initially formed azomethine imine, followed by onepot aromatization of the formed pyrazolidine ring. (C) 2015 Elsevier Ltd. All rights reserved.