Synthesis of trifluoroethoxy/aryloxy cinnolines, cinnolinones and indazoles from o -alkynylanilines via metal-free diazotization reagent.

A facile and user-friendly protocol for the synthesis of trifluoroethoxy/aryloxy cinnolines, cinnolinones and indazoles from o -alkynylaniline in good-to-excellent yields has been developed using a metal-free diazotization reagent (a combination of BF 3 ·OEt 2 and TBN). The methodology has been further extended to construct bis-cinnolinones and for the chemoselective synthesis of N -propargylated cinnolinones.