Mercaptan-free approach to the synthesis of Ethiprole, an insecticide

Abstract

An efficient and practical method has been developed for the synthesis of a second-generation insecticide, ethiprole. The key step involved in this approach is the thiocynation of pyrazole ring at the 4th position, which was achieved using bromine and potassium thiocyanate in methanol. Another important step involves the one-pot conversion of thiocyanate into ethyl sulfide using ethyl bromide in the presence of a base. Each step in this synthesis was performed efficiently on a gram scale to produce high-quality product. This new synthetic strategy is simple, convenient and scalable.