Syntheses of Bromo-N-heterocycles through Dibromohydantoin-Promoted Tandem C–H Amination/Bromination

Synthesis of 1,2-Benzothiazine via Nickel-Catalyzed Electrochemical Intramolecular Amination

Constructing a C-N bond by merging electrochemistry and nickel catalysis is considered a powerful strategy. Herein, we investigate highly efficient intramolecular amination at room temperature with excellent functional group tolerance. Mechanistic studies suggest that the rapid ligand exchange may lead to the NiI/NiIII catalytic cycle. This method not only provides a new perspective for intramolecular amination but also offers a novel approach for constructing the benzothiazine scaffold.

A rhodium-catalyzed cascade C-H activation/annulation strategy for the expeditious assembly of pyrrolidinedione-fused 1,2-benzothiazines

A cascade annulation strategy triggered by rhodium(III)-catalyzed C-H activation has been reported for the expeditious assembly of pyrrolidinedione-fused 1,2-benzothiazines from free NH-sulfoximines with maleimides under mild conditions. Without the need for inert atmosphere protection, a broad range of sulfoximines with maleimides were well tolerated, producing diverse fused-thiazine derivatives in moderate to good yields. Additionally, the late-stage transformation of the target product demonstrated the potential synthetic value of this protocol.

Recent Advances in the Synthesis of Cyclic Sulfoximines via C-H Bond Activation

Sulfoximines, a ubiquitous class of structural motifs, are widely present in bioactive molecules and functional materials that have received considerable attention from modern organic chemistry, pharmaceutical industries, and materials science. Sulfoximines have proved to be an effective directing group for C-H functionalization which was widely investigated for the synthesis of cyclic sulfoximines. Within the last decade, great progress has been achieved in the synthesis of cyclic sulfoximines. Thus, this review highlights the recent advances in the synthesis of cyclic sulfoximines via the C-H activation strategy and is classified based on the substrate types.

Sulfoxylate Anion Radical-Induced Aryl Radical Generation and Intramolecular Arylation for the Synthesis of Biarylsultams

Aryl radical generation from the corresponding aryl halides using an electron donor and subsequent intramolecular cyclization with arenes could be an important advancement in contemporary biaryl synthesis. A green and practically useful synthetic protocol to access diverse six- and seven-membered biarylsultams especially with a free NH group including demonstration of a gram-scale synthesis is reported herein. The sulfoxylate anion radical (SO₂^-•), generated in situ from the reagents rongalite or sodium dithionite (Na₂S₂O₄), was found to be the key single electron transfer agent forming aryl radicals from aryl halides, which upon intramolecular arylation gives biarylsultams with good to excellent yields. The approach features generation of aryl radicals that remained underexplored, use of a cheap and readily available industrial reagents, and transition metal-free, mild, and green reaction conditions.

Catalyst-Free 1,2-Dibromination of Alkenes Using 1,3-Dibromo-5,5-dimethylhydantoin (DBDMH) as a Bromine Source

A direct 1,2-dibromination method of alkenes is realized using 1,3-dibromo-5,5-dimethylhydantoin (DBDMH) as a bromine source. This reaction proceeds under mild reaction conditions without the use of a catalyst and an external oxidant. Various sorts of alkene substrates are transformed into the corresponding 1,2-dibrominated products in good to excellent yields with broad substrate scope and exclusive diastereoselectivity. This method offers a green and practical approach to synthesize vicinal dibromide compounds.

Environmentally friendly catechol-based synthesis of dibenzosultams

A scalable reaction for the synthesis of dibenzosultams in water with the aid of K2CO3 and air.

Electrochemical Synthesis of Cyclic Diaryl Phosphinamides via Intramolecular sp2 C-H Phosphinamidation

We developed an oxidant- and transition-metal-free approach to construct six-membered cyclic phosphinamides via an intramolecular electrochemical C-H phosphinamidation process. With ⁿBu₄NBr as the catalyst and electrolyte, cyclic phosphinamides bearing a variety of functional groups (22 examples) were readily accessed under mild conditions. Meanwhile, this protocol provided an alternative route to organic electroluminescent materials and P-N ligands.

Synthesis of Six-Membered N-Heterocycle Frameworks Based on Intramolecular Metal-Free N-Centered Radical Chemistry

The formation of intramolecular C-N bond represents a powerful strategy in organic transformation as the great importance of N-heterocycles in the fields of natural products and bioactive molecules. This personal account describes the synthesis of cyclic phosphinamidation, benzosultam, benzosulfoximine, phenanthridine and their halogenated compounds through transition-metal-free intramolecular oxidative C-N bond formation. Mechanism study reveals that N-X bond is initially formed under the effect of hypervalent halogen, which is very unstable and easily undergoes thermal or light homolytic cleavage to generate nitrogen radical. Then the nitrogen radical is trapped by the arene to give aryl radical. Rearomatization of aryl radical under the oxidant to provide corresponding N-heterocycle. Under suitable conditions, the N-heterocycles can be further transformed to halogenated N-heterocycles.

More Twins in the Scientific Literature of the 21st Century

This Essay highlights the complex issue of twinning in science publications. Historical accounts present cases where two scientists focused on the same problem and came up with the same solution following different paths. This has changed in the present day. The concurrent publication of rather similar research papers from different groups has increased in frequency since 2010. In the past, twinning in research publications was serendipitous, and there was a healthy competition among teams working on similar projects. Today, twinning has become more frequent. This can be attributed to the urge of researchers to have publications on popular topics, the tendency to base research programs on popular keywords, and funding agencies preferentially supporting certain areas of research. With vast amounts of literature being generated, editorial offices and referees may not be able to find these twins very easily. As we inch away from human ingenuity towards artificial intelligence, twinning may become even more frequent.

Differential formation of nitrogen-centered radicals leading to unprecedented, regioselective bromination of N,N′-(1,2-phenylene)bisamides and 2-amidophenols

A highly efficient, site-selective, visible light-accelerated, remote C–H halogenation of unsymmetrical aromatic bisamides/amidoesters has been developed.