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.

Visible-Light-Promoted Enantioselective α-Amidation of Aldehydes by Harnessing Organo-Iron Dual Catalysis

“…Formation of the resultant iron-nitrenoid D is exergonic (−12.8 kcal/mol). Mulliken spin density plot of D shows that most of the unpaired electrons are located on the FeCl 3 – fragment (4.713α) and N atom (−0.761β), suggesting that D is better to view as a high-spin Fe(III)-imidyl radical, consistent with the previous characterization of an iron-nitrenoid. ,,− …”

“…The iron-catalyst was found to be essential for furnishing the desired amidated products (Table , entry 9), serving to activate dioxazolones. In fact, the Chen , and Bao , groups independently showcased the reactivity of dioxazolones with FeCl 2 or FeCl 3 . To elucidate the major iron species responsible for this reaction, UV–Vis spectroscopy was examined.…”

Synthesis of N–H Aziridines from Unactivated Olefins Using Hydroxylamine-O-Sulfonic Acids as Aminating Agent

“…In 1957, Meuwsen and Gösl discovered that tertiary amines and heterocyclic amines, such as trimethylamine (Me 3 N), pyridine, and quinoline, could react with HOSA to yield N-aminated products through a proposed nitrene intermediate . As part of an ongoing program aimed at exploring nitrene chemistry, we envisioned whether olefin aziridination could be achieved in this reaction system. Drawing inspiration from Kürti’s seminal work, we used ( Z )-cyclooctene 1a as the model substrate and HOSA as the aminating agent.…”

Recent Advances in Catalytic Nitrogen–Nitrogen Bond Formation Reactions

“…The mechanistic studies indicated that the electrophilic metal–nitrenoid intermediate attacked with the assistance by Cl–HN bonding to outcompete the Curtius rearrangement to generate the product. A recent work from the same lab demonstrated that through the design of phosphine ligands, the reaction can be significantly accelerated and the scope of arylamines expanded under FeCl 2 -catalyzed conditions …”