seco-Cyclothialidines are a promising class of bacterial DNA gyrase B subunit inhibitors. A new seco-cyclothialidine derivative containing a dioxazine moiety, BAY 50-7952, was synthesized through a new concise pathway. One key step of the synthesis is the straightforward formation of the 2-aminothiazole derivative of S-tritylcysteine. In biological tests, BAY 50-7952 and other known seco-cyclothialidines exhibited high and selective ...