Ru(II)-Catalyzed C–H activation/annulation reactions of N-aryl-pyrazolidinones with sulfoxonium ylides: synthesis of cinnoline-fused pyrazolidinones

The first Ru(II)-catalyzed cascade C–H activation/annulation reactions of N-aryl-pyrazolidinones with sulfoxonium ylides for the synthesis of cinnoline-fused pyrazolidinones are reported. This transformation proceeds smoothly under operationally simple conditions in 10 min using a simple and cheap catalytic system consisting of Ru(II) and Zn(OTf)2. A wide range of substrates were assessed in this transformation, and the products were isolated in good to excellent yields (51% to 99%).