Divergent synthesis of fused N-heterocyclesviarhodium-catalysed [4 + 2] cyclization of pyrazolidinones with iodonium ylides

We developed a catalytic system-controlled tunable strategy for the divergent synthesis of cinnolines and pyrazolo[1,2- a ]cinnolines via the rhodium-catalyzed [4 + 2] cyclization of easily available pyrazolidinones and iodonium ylides.