Green hydrothiolation of dialkyl azodicarboxylates

Hydrothiolations are the most useful and atom-economical pathway for the generation of sulfur-carbon and sulfur-nitrogen bonds. In particular, the preparation of sulfenylhydrazines-1,2-dicarboxylates by sulfur functionalization of nitrogen-nitrogen double bonds has received great interest in organic synthesis of compounds of unique biological properties. Previous protocols have drawbacks such as long reaction times and the use of toxic solvents. Here, we describe the preparation of sulfenylhydrazines-1,2-dicarboxylates by hydrothiolation of dialkyl azodicarboxylates under neat conditions. This new eco-friendly methodology afforded the products in up to 99% yield, in only 5 min at room temperature. A possible reaction mechanism is proposed.