Palladium-catalyzed C-H cyclization in water: A milder route to 2-arylbenzothiazoles

Water was successfully employed as a reaction medium in palladium-catalyzed C-H cyclization of thiobenzanilides. Reactions efficiently proceeded under considerably mild conditions such as 40 °C in water, providing a more practical, greener method for the synthesis of 2-arylbenzothiazoles. For some substrates, the addition of an amphiphilic surfactant greatly enhanced the process. The method represents a rare example of palladium-catalyzed C-H functionalization processes performed in water.