Coupled Flavin-Iodine Redox Organocatalysts: Aerobic Oxidative Transformation from N-Tosylhydrazones to 1,2,3-Thiadiazoles

A bioinspired two-component redox organocatalyst system using 1,10-bridged flavinium and NH4I was developed to perform environmentally friendly aerobic oxidative ring formation of 1,2,3-thiadiazoles from N-tosylhydrazones and sulfur. The redox organocatalysis of the flavinium promoted the iodine-catalyzed system without the use of any sacrificial reagents, except for environmentally benign molecular oxygen.