Synthesis of 3-chalcogenyl-indoles mediated by the safer reagent urea-hydrogen peroxide (UHP)

Herein, we report the use of urea-hydrogen peroxide (UHP) as an oxidizing agent in the direct C3 chalcogenylation of indoles with diorganyl dichalcogenides, in the presence of an iodine source. This reagent provided a simple, efficient and safer reaction media, besides avoid problems related to the aqueous solutions oxidants. This method allowed the preparation of 20 compounds in good to excellent yields, being efficient also in large scale.