One-Pot Synthesis of 3-Aryl-5-amino-1,2,4-thiadiazoles from Imidates and Thioureas by I2-Mediated Oxidative Construction of the N-S Bond

A simple and practical method for the one-pot synthesis of 3-aryl-5-amino-1,2,4-thiadiazoles from imidates and thioureas has been developed. The protocol proceeds through sequential base-mediated nucleophilic addition-elimination reactions and an I-2-mediated oxidative coupling for the N-S bond formation. The approach employes readily available and nontoxic substrates and a simple workup to provide 3-aryl-5-amino-1,2,4-thiadiazoles that have a free or substituted amino group.