Ligand-free iron-catalyzed benzylic C (sp3)–H amination of methylarenes with N-fluorobenzenesulfonimide

Conversion of a AuI Fluorido Complex into an N-Fluoroamido Derivative: N-F versus Au-N Reactivity

The Au^I complex [Au{N(F)SO₂ Ph}(SPhos)] (SPhos=dicyclohexyl(2',6'-dimethoxy[1,1'-biphenyl]-2-yl)phosphane) (2) bearing a fluoroamido ligand has been synthesized by reaction of the fluorido complex [Au(F)(SPhos)] (1) with NFSI (NFSI=N-fluorobenzenesulfonimide). A reaction with CO resulted in an unprecedented insertion into the N-F bond at 2. With the carbene precursor N₂ CH(CO₂ Et) N-F bond cleavage gave the Au-F bond insertion product [Au{CHF(CO₂ C₂ H₅ )}(SPhos)] (7). The presence of CNtBu led to Au-N cleavage at 2 and concomitant amide formation to give the cationic complex [Au(CNtBu)(SPhos)][N(F)SO₂ Ph)] (5), which reacted further to give FtBu as well as the cyanido complex [Au(CN)(SPhos)] (6). These results led to the development of a process for the amination of electrophilic organic substrates by transfer of the fluoroamido group NF(SO₂ Ph)^- .

Iron-Catalyzed Oxidative Amination of Benzylic C(sp3)-H Bonds with Anilines

Iron-catalyzed oxidative amination of benzylic C(sp³)-H bonds with anilines bearing electron-withdrawing groups (EWGs) or electron-donating groups (EDGs) is realized based on simple variations of N-substituents on imidazolium cations in novel ionic Fe(III) complexes. The structural modification of the imidazolium cation resulted in regulation of the redox potential and the catalytic performance of the iron metal center. Using DTBP as oxidant, [HItBu][FeBr₄] showed the highest catalytic activity for anilines bearing EWGs, while [HIPym][FeBr₄] was more efficient for EDG-substituted anilines. This work provides alternative access to benzylamines with the advantages of both a wide substrate scope and iron catalysis.

Ligand-free copper-catalyzed C(sp3)-H imidation of aromatic and aliphatic methyl sulfides with N-fluorobenzenesulfonimide

A novel and efficient process has been developed for copper-catalyzed C(sp3)-H direct imidation of methyl sulfides with N-fluorobenzenesulfonimide(NFSI). Without using any ligands, various methyl sulfides including aromatic and aliphatic methyl sulfides, can be transformed to the corresponding N-((phenylthio)methyl)-benzenesulfonamide derivatives in good to excellent yields.

Iodine-catalyzed oxidative functionalization of purines with (thio)ethers or methylarenes for the synthesis of purin-8-one analogues

An efficient oxidative functionalization of purine-like substrates with (thio)ethers or methylarenes under mild conditions is described. Using I2 as the catalyst, and TBHP as the oxidant, this protocol provides a valuable synthetic tool for the assembly of a wide range of 9-alkyl(benzyl)purin-8-one derivatives with high atom- and step-economy and exceptional functional group tolerance.

Synergetic copper/TEMPO-catalysed benzylic C–H imidation with N-fluorobenzenesulfonimide at room temperature and tandem conversions with alcohols or arenes

A remote carbamate-directed benzylic C–H imidation with NFSI at room temperature through synergetic CuCl-TEMPO catalysis and tandem alkoxylation or arylation with alcohols or arenes are described.

Exploring the behavior of the NFSI reagent as a nitrogen source

The diverse biological activities of nitrogen-containing compounds make the construction of the C-N bond of great importance. As N-fluorobenzenesulfonimide, one of the most abundant chemical feedstock, has a dual behaviour, i.e. as an electrophilic fluorination and amidation source, it attracts the attention of synthetic chemists for exploitation. This review comprehensively summarizes the significant progress of the efficient and mild amidation reactions, with an emphasis on approaches for the generation of nitrogen-centered intermediates, related mechanisms and new synthetic chemistry methods that offer opportunities to overcome obstacles in pharmaceutical applications. In this perspective, we discuss the developments in the amidation reaction using NFSI in the past decade. We discuss the recent progress, challenges and future outcomes in the area of amidation chemistry using commercially available NFSI.

Iron-Catalyzed Oxidative Coupling of Indoline-2-ones with Aminobenzamides via Dual C-H Functionalization

We describe an unprecedented dual C-H functionalization of indolin-2-one via an oxidative C(sp³)-H/N-H/X-H (X = N, C, S) cross-coupling protocol, which is catalyzed by a simple iron salt under mild and ligand-free conditions and employs air (molecular oxygen) as the terminal oxidant. This method is readily applicable for the construction of tetrasubstituted carbon centers from methylenes and provides a wide variety of spiro N-heterocyclic oxindoles.