Photoredox-catalyzed unsymmetrical diamination of alkenes for access to vicinal diamines

A photoredox-catalyzed unsymmetrical diamination of alkenes by using N-aminopyridinium salts and nitriles as the amination reagents has been developed. Various vicinal diamines were obtained in moderate to excellent yields under mild reaction conditions. Furthermore, this protocol could be applied in the late-stage modification of pharmaceuticals and natural products. Preliminary mechanistic studies suggested that this methodology may undergo a radical pathway followed by a Ritter-type reaction.

Iron-Catalyzed Site- and Regioselective 1,2-Azidoamidations of 1,3-Dienes

The direct 1,2-azidoamidation of unsaturated precursors represents an advantageous approach for the facile synthesis of β-functionalized azides from readily available starting materials. In this paper, we describe a convenient and mild iron-catalyzed 1,2-azidoamidation of 1,3-dienes that shows excellent functional group compatibility to furnish versatile precursors to 1,2-diamine products with high levels of site, regio-, and stereoselectivity. The reaction is proposed to proceed via a single electron transfer/radical addition/C-N bond formation relay process.

Divergent Trideuteromethylthiolation and Aminotrideuteromethylthiolation of Alkenes with N-Fluorobenzenesulfonimide and CD3SSO3Na

A metal-free oxidative trideuteromethylthiolation of alkenes with CD3SSO3Na using NFSI as an oxidant has been developed. The aminotrideuteromethylthiolation of a three-component reaction could be easily achieved in the presence of a cobalt catalyst. The divergent trideuteromethylthiolation of alkenes, readily available trideuteromethylthiolation reagent, and versatile synthetic strategy allow for late-stage modification of drug molecules.

Modular and practical diamination of allenes

Vicinal diamines are privileged scaffolds in medicine, agrochemicals, catalysis, and other fields. While significant advancements have been made in diamination of olefins, diamination of allenes is only sporadically explored. Furthermore, direct incorporation of acyclic and cyclic alkyl amines onto unsaturated π systems is highly desirable and important, but problematic for many previously reported amination reactions including the diamination of olefins. Herein, we report a modular and practical diamination of allenes, which offers efficient syntheses of β,γ-diamino carboxylates and sulfones. This reaction features broad substrate scope, excellent functional group tolerability, and scalability. Experimental and computational studies support an ionic reaction pathway initiated with a nucleophilic addition of the in situ formed iodoamine to the electron deficient allene substrate. An iodoamine activation mode via a halogen bond with a chloride ion was revealed to substantially increase the nucleophilicity of the iodoamine and lower the activation energy barrier for the nucleophilic addition step.

The advent of electrophilic hydroxylamine-derived reagents for the direct preparation of unprotected amines

Electrophilic aminating reagents have seen a renaissance in recent years as effective nitrogen sources for the synthesis of unprotected amino functionalities. Based on their reactivity, several noble and non-noble transition metal catalysed amination reactions have been developed. These include the aziridination and difunctionalisation of alkenes, the amination of arenes as well as the synthesis of aminated sulfur compounds. In particular, the use of hydroxylamine-derived (N-O) reagents, such as PONT (PivONH3OTf), has enabled the introduction of unprotected amino groups on various different feedstock compounds, such as alkenes, arenes and thiols. This strategy obviates undesired protecting-group manipulations and thus improves step efficiency and atom economy. Overall, this feature article gives a recent update on several reactions that have been unlocked by employing versatile hydroxylamine-derived aminating reagents, which facilitate the generation of unprotected primary, secondary and tertiary amino groups.

Direct Benzylic C(sp3)-O Coupling with Alcohol via Site-Selective C(sp3)-H Cleavage at Room Temperature through a Remote Directing Group-Enabled Radical Relay Strategy

Employing a low loading of the terminal oxidant, a remote directing group-enabled radical relay strategy for benzylic direct C(sp³)-H alkoxylation with alcohols at room temperature is developed. Satisfactory site-selectivity, chemoselectivity, and reaction scope are achieved under simple and mild conditions, and no ligand or additive is required. Mechanistic studies, ready conversions of the directing group, and other benzylic functionalizations currently under development in our laboratory further indicate the promising potentials of this remote directing group-enabled radical relay strategy.

Remote carbamate-directed site-selective benzylic C–H oxygenation via synergistic copper/TEMPO catalysis at room temperature

A benzylic C(sp3)–H oxygenation with water at room temperature through a ligand- and additive-free synergistic copper/TEMPO-catalysed radical relay pathway and a remote directing strategy is described.

Copper-Catalyzed Aminoarylation of Alkenes via Aminyl Radical Addition and Aryl Migration

We describe a new strategy for aminoarylation of alkenes by copper-catalyzed smiles rearrangement using O-benzoylhydroxylamines as the amine reagent. This method affords various β-amino amide derivatives possessing a quaternary carbon center with wide functional group tolerance and high regioselectivity. The mechanistic studies indicate that the transformation can involve aminyl radical intermediates under acid-free condition.

Visible-light enabled room-temperature dealkylative imidation of secondary and tertiary amines promoted by aerobic ruthenium catalysis

Employing sulfonyl azide as a nitrogen donor, a visible-light-enabled aerobic dealkylative imidation of tertiary and secondary amines involving C(sp³)–C(sp³) bond cleavage with moderate to excellent yields at room temperature is described. It has been demonstrated that this imidation could take place spontaneously upon visible-light irradiation, and could be facilitated considerably by a ruthenium photocatalyst and oxygen. An alternative mechanism to the previous aerobic photoredox pathway has also been proposed.

A photoredox dealkylative imidation of tertiary and secondary amines with sulfonyl azide facilitated by aerobic ruthenium-catalysis to afford sulfonyl amidine at room temperature is reported.

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.

Transition Metal Catalyzed Azidation Reactions

A wide range of methodologies for the preparation of organic azides has been reported in the literature for many decades, due to their interest as building blocks for different transformations and their applications in biology as well as in materials science. More recently, with the spread of the use of transition metal-catalyzed reactions, new perspectives have also materialized in azidation processes, especially concerning the azidation of C–H bonds and direct difunctionalization of multiple carbon-carbon bonds. In this review, special emphasis will be placed on reactions involving substrates bearing a leaving group, hydroazidation reactions and azidation reactions that proceed with the formation of more than one bond. Further reactions for the preparation of allyl and vinyl azides as well as for azidations involving the opening of a ring complete the classification of the material.

Iron-Catalyzed Alkylazidation of 1,1-Disubstituted Alkenes with Diacylperoxides and TMSN3

An iron-catalyzed radical alkylazidation of electron-deficient alkenes is reported. Alkyl diacyl peroxides work as the alkyl source, and trimethylsilyl azide acts as the azido reservoir. This method features mild reaction conditions, wide substrate scope, and good functional group tolerance, providing a range of α-azido esters, an α-azido ketone, and an α-azido cyanide in high yields. These azides can be easily transferred into many kinds of amino acid derivatives.

Exploring the behavior of the NFSI reagent as a nitrogen source

Applications of the N-fluorobenzenesulfonimide (NFSI) reagent in organic synthesis.

Efficient metal-free aminoiodination of alkenes with N-fluorobenzenesulfonimide under mild conditions

A novel regioselective and stereoselective transition-metal-free aminoiodination of alkenes through an iodonium intermediate using NFSI as both the oxidant and amino precursor under mild conditions with a broad alkene scope is disclosed.

Metal-free C–H amination of arene with N-fluorobenzenesulfonimide catalysed by nitroxyl radicals at room temperature

The first C–H amination of arene with NFSI via organocatalysis is disclosed, which can be achieved at room temperature with a broad substrate scope.