Synthesis and antitumor evaluation of fluoroquinolone C3 fused heterocycles （II）： From triazolothiadiazines to pyrazolotriazoles

To further expand an effective modified route for the shift from an antibacterial fluoroquinolone （FQ） to an antitumor FQ, two series of title compounds based on an isostere of the FQ C3 carboxylic group with two fused heterocyclic rings, [ 1,2,4]triazolo[3,4- b][1,3,4]thiadiazine and pyrazolo[5,1-c][1,2,4]triazole, respectively, were designed and synthesized starting from the current antibacterial FQs, and their in vitro antitumor activity against L1210, CHO cell lines were evaluated via their respective IC50 values.