Ligand-Promoted Iron-Catalyzed Nitrene Transfer for the Synthesis of Hydrazines and Triazanes through N-Amidation of Arylamines

Abstract

Herein, we report that bulky alkylphosphines such as PtBu₃ can switch the roles from actor to spectator ligands to promote the FeCl₂ -catalyzed N-amidation reaction of arylamines with dioxazolones, giving hydrazides in high efficiency and chemoselectivity. Mechanistic studies indicated that the phosphine ligands could facilitate the decarboxylation of dioxazolones on the Fe center, and the hydrogen bonding interactions between the arylamines and the ligands on Fe nitrenoid intermediates might play a role in modulating the delicate interplay between the phosphine ligand, arylamine, and acyl nitrene N, favoring N-N coupling over N-P coupling. The new ligand-promoted N-amidation protocols offer a convenient way to access various challenging triazane compounds via double or sequential N-amidation of primary arylamines.

Keywords: Iron Catalysis; Ligand Acceleration; Nitrenoid; N−N Coupling; Triazane.