The synthesis of arylhydrazines through C–N cross-coupling of aryl chlorides with hydrazine is described. Through the use of continuous flow, the hazards associated with the use of hydrazine in the presence of transition metals are decreased. In addition, multistep flow sequences have also been developed for the generation of functionalized heterocycles utilizing the arylhydrazine intermediates.
“Mild and Rapid Pd-Catalyzed Cross-Coupling with Hydrazine in Continuous Flow: Application to the Synthesis of Functionalized Heterocycles”, Angew. Chem. Int. Ed., 2013, 52(12), 3434 - 3437.