Nitrogen Insertion Research Articles

Selectively Extending the Curved Side of N-Doped Hexa-peri- hexabenzocoronene.

A curved nanographene, conceptually by insertion of nitrogen into a trapezoidal planar nanographene at the edge was synthesized by π-extension of the nitrogen-doped hexa-peri-hexabenzocoronene. This N-doped nanographene exhibited a π-electronic concave face containing a nonaromatic azepine ring in the middle with a size of 14.0 Å length and 4.0 Å depth, which represents an unprecedented half-side concave geometry of curved nanographene. The bent π-extension exhibited a low degree of conjugation suggested by calculation results. Due to the unique 3D structure and electron-rich property, this nanographene showed pronounced intermolecular charge transfer with C60.

Direct oxygen insertion into C-C bond of styrenes with air.

Skeletal editing of single-atom insertion to basic chemicals has been demonstrated as an efficient strategy for the discovery of structurally diversified compounds. Previous endeavors in skeletal editing have successfully facilitated the insertion of boron, nitrogen, and carbon atoms. Given the prevalence of oxygen atoms in biologically active molecules, the direct oxygenation of C-C bonds through single-oxygen-atom insertion like Baeyer-Villiger reaction is of particular significance. Herein, we present an approach for the skeletal modification of styrenes using O2 via oxygen insertion, resulting in the formation of aryl ether frameworks under mild reaction conditions. The broad functional-group tolerance and the excellent chemo- and regioselectivity are demonstrated in this protocol. A preliminary mechanistic study indicates the potential involvement of 1,2-aryl radical migration in this reaction.

Skeletal Editing by Hypervalent Iodine Mediated Nitrogen Insertion.

Hypervalent iodine reagents are versatile and readily accessible reagents that have been extensively applied in contemporary synthesis in modern organic chemistry. Among them, iodonitrene (ArI=NR), is a powerful reactive species, widely used for a single-nitrogen-atom insertion reaction, and skeletal editing to construct N-heterocycles. Skeletal editing with reactive iodonitrene components has recently emerged as an exciting approach in modern chemical transformation. These reagents have been extensively used to produce biologically relevant heterocycles and functionalized molecular architectures. Recently, the insertion of a nitrogen-atom into hydrocarbons to generate N-heterocyclic compounds using hypervalent iodine reagents has been a significant focus in the field of molecular editing reactions. In this review, we discuss the rapidly emerging field of nitrene insertion, including skeletal editing and nitrogen insertion, using hypervalent iodine reagents to access nitrogen-containing heterocycles, and the current mechanistic understanding of these processes.

Selective nitrogen insertion into aryl alkanes

Molecular structure-editing through nitrogen insertion offers more efficient and ingenious pathways for the synthesis of nitrogen-containing compounds, which could benefit the development of synthetic chemistry, pharmaceutical research, and materials science. Substituted amines, especially nitrogen-containing alkyl heterocyclic compounds, are widely found in nature products and drugs. Generally, accessing these compounds requires multiple steps, which could result in low efficiency. In this work, a molecular editing strategy is used to realize the synthesis of nitrogen-containing compounds using aryl alkanes as starting materials. Using derivatives of O-tosylhydroxylamine as the nitrogen source, this method enables precise nitrogen insertion into the Csp2-Csp3 bond of aryl alkanes. Notably, further synthetic applications demonstrate that this method could be used to prepare bioactive molecules with good efficiency and modify the molecular skeleton of drugs. Furthermore, a plausible reaction mechanism involving the transformation of carbocation and imine intermediates has been proposed based on the results of control experiments.

Oxidative Nitrogen Insertion into Silyl Enol Ether C═C Bonds.

Here, we demonstrate a fundamentally new reactivity of the silyl enol ether functionality utilizing an in situ-generated iodonitrene-like species. The present transformation inserts a nitrogen atom between the silyl enol ether olefinic carbons with the concomitant cleavage of the C═C bond. Overall, this facile transformation converts a C-nucleophilic silyl enol ether to the corresponding C-electrophilic N-acyl-N,O-acetal. This unprecedented access to α-amido alkylating agents enables modular derivatization with carbon and heteroatom nucleophiles and the unique late-stage editing of carbon frameworks. The reaction efficiency of this transformation is well correlated with enol ether nucleophilicity as described by the Mayr N scale. Applications presented herein include late-stage nitrogen insertion into carbon skeletons of natural products with previously unattainable regioselectivity as well as modified conditions for 15N labeling of amides and lactams.

Examining the dual effect of copper nanoparticles and nitrogen doping on Cu@N-TiO2

Abstract The study of six compositions of Cu@N-TiO2 with different amounts of copper and nitrogen synthesized using a sol–gel method is reported. X-ray diffraction patterns and Raman spectra indicated the formation of a single anatase TiO2 phase in all materials without evidence of secondary phases including copper or nitrogen. Electron microscopy images showed a homogeneous distribution of the copper particles around a TiO2 matrix, just as that the insertion of nitrogen did not have a significant effect on the morphology of the particles. X-ray photoelectron spectroscopy analysis confirmed that nitrogen was inserted in the atomic arrangement of titanium dioxide, while copper was presented mainly as metallic element on the TiO2 surface. Characterization of the optical properties and photoactivity test confirm that band gap strongly depends on the copper and nitrogen content phenomenon attributed to the combined presence of modifiers over the TiO2 surface and the promotion of a plasmonic effect, which displaced the absorption UV bands to higher wavelengths with respect to un-doped TiO2. The catalytic test performed using rhodamine-B as probe molecule, confirm that TiCuN2 and TiCuN3 samples exhibit the best decomposition percentages of 38 and 36 % respectively. Such results confirm the surface plasmon resonance effect associated to Cu particles on the TiO2 as main cause in the increase in current along synthesized samples and the use of cyclic voltammetry technique to identify these effects between 0.0 and 1.5 V.

Phase manipulating toward Ni catalysts via lattice nitrogen endows high energy density hydrogen gas battery

Metastable structures commonly generate unique catalytic effects. However, it is challenging to prepare due to thermodynamic limitations. Here, we first propose a nitrogen insertion strategy for Ni phase manipulating in alkaline hydrogen oxidation reaction (HOR). With the incremental lattice nitrogen, face centered cubic (fcc), bi-mixed fcc and N-induced an unconventional hexagonal close packed (N-u-hcp), tri-mixed fcc-Ni/N-u-hcp-Ni/Ni3N and Ni3N phase evolves successively, with corresponding volcanic HOR activities. Specifically, the biphasic fcc-Ni/N-u-hcp-Ni shows highest activity of 67 A g−1. Theoretical calculations show that lattice nitrogen reduce the formation energy of biphasic Ni, and this biphasic structure could provide electron rich interface to optimize the adsorption of H* and OH*. As a proof-of-concept for Ni-H2 battery, the gas diffusion electrode prepared with this biphasic Ni catalyst achieves an 8 Ah Ni-H2 battery with 163 Wh kg−1. This study provides an inspiration for the controllable synthesis of metastable nano-catalysts and demonstrates the efficient catalysis in practical hydrogen energy applications.

Carbon–nitrogen transmutation in polycyclic arenol skeletons to access N-heteroarenes

Developing skeletal editing tools is not a trivial task, and realizing the corresponding single-atom transmutation in a ring system without altering the ring size is even more challenging. Here, we introduce a skeletal editing strategy that enables polycyclic arenols, a highly prevalent motif in bioactive molecules, to be readily converted into N-heteroarenes through carbon–nitrogen transmutation. The reaction features selective nitrogen insertion into the C–C bond of the arenol frameworks by azidative dearomatization and aryl migration, followed by ring-opening, and ring-closing (ANRORC) to achieve carbon-to-nitrogen transmutation in the aromatic framework of the arenol. Using widely available arenols as N-heteroarene precursors, this alternative approach allows the streamlined assembly of complex polycyclic heteroaromatics with broad functional group tolerance. Finally, pertinent transformations of the products, including synthesis complex biheteroarene skeletons, were conducted and exhibited significant potential in materials chemistry.

Induced red emission and diamagnetic maintenance in cubic Sb2O3 nanostructures via nitrogen insertion

Induced red emission and diamagnetic maintenance in cubic Sb2O3 nanostructures via nitrogen insertion

Skeletal Editing of Indoles and Pyrroles by LiHMDS Nitrogen Insertion Reaction

Skeletal Editing of Indoles and Pyrroles by LiHMDS Nitrogen Insertion Reaction

Precision single-atom editing: new frontiers in nitrogen insertion and substitution for the generation of N-heterocycles

This paper primarily focuses on the editing of nitrogen atoms, encompassing the insertion of N, substitution of C with N, and utilization of 15N in place of 14N for the construction of N-heterocycles.

γ-Lactam synthesis from cyclobutanone via transoximation and the Beckmann rearrangement.

This manuscript describes the synthesis of γ-lactam from the nitrogen insertion reaction of cyclobutanones using an oxime as an aminating reagent with a catalytic amount of Brønsted acid. This method was employed with a more stable oxime reagent, which is a precursor analog of hydroxylamine derivatives with explosive properties. The reaction was tolerated by various substituted cyclobutanones and less strained five- or six-membered ketones. The obtained γ-lactam products could be transformed into γ-aminobutyric acid derivatives via ring-opening hydrolysis. The reaction mechanism is discussed from the perspective of the isotope effect, etc.

Olefin skeletal rearrangement enabling access to multiarylated N-sulfonyl amidines.

A base-promoted olefin skeletal rearrangement strategy from para-quinone methides (p-QMs) and N-fluoroarenesulfonamides is reported, enabling direct nitrogen insertion of olefins to produce a series of multiarylated (Z)-N-sulfonyl amidines with complete stereoselectivity and generally good yields. Using p-QMs without o-hydroxy substituents gave triarylated N-sulfonyl amidines, whereas tetraarylated N,N'-disulfonyl amidines were synthesized with the existence of o-hydroxy groups.

A Photochemical Strategy for the Conversion of Nitroarenes into Rigidified Pyrrolidine Analogues.

Bicyclic amines are important motifs for the preparation of bioactive materials. These species have well-defined exit vectors that enable accurate disposition of substituents toward specific areas of chemical space. Of all possible skeletons, the 2-azabicyclo[3.2.0]heptane framework is virtually absent from MedChem libraries due to a paucity of synthetic methods for its preparation. Here, we report a modular synthetic strategy that utilizes nitroarenes as flat and easy-to-functionalize feedstocks for the assembly of these sp3-rich materials. Mechanistically, this approach exploits two concomitant photochemical processes that sequentially ring-expand the nitroarene into an azepine and then fold it into a rigid bicycle pyrroline by means of singlet nitrene-mediated nitrogen insertion and excited-state-4π electrocyclization. A following hydrogenolysis provides, with full diastereocontrol, the desired bicyclic amine derivatives whereby the aromatic substitution pattern has been translated into the one of the three-dimensional heterocycle. These molecules can be considered rigid pyrrolidine analogues with a well-defined orientation of their substituents. Furthermore, unsupervised clustering of an expansive virtual database of saturated N-heterocycles revealed these derivatives as effective isosteres of rigidified piperidines. Overall, this platform enables the conversion of nitroarene feedstocks into complex sp3-rich heterocycles of potential interest to drug development.

Uniaxial magnetic anisotropy of L10-FeNi films with island structures on LaAlO3(110) substrates by nitrogen insertion and topotactic extraction

Tetrataenite (L10-FeNi) has potential for application in next-generation permanent magnets. This compound is a rare-earth-free material comprising Fe and Ni, which are abundant elements. In addition, an extremely high uniaxial magnetocrystalline anisotropy (Ku) is expected for L10-FeNi because of the ordered arrangement of the elements. This study reports the magnetic properties of uniaxially oriented L10-FeNi films with island structures fabricated by a novel method involving the radio-frequency sputter deposition of FeNi alloy films onto a LaAlO3 (LAO)(110) substrate, followed by nitrogen insertion and topotactic extraction. FeNiN(110) films are epitaxially grown on the LAO(110) plane by the nitriding and additional annealing process of the FeNi alloy films at high temperatures under ammonia gas to reduce the volume fraction of crystallographic variants. Uniaxially oriented L10-FeNi alloy films with island structures are obtained after the topotactic denitriding of the FeNiN films. The uniaxial magnetic anisotropy of the L10-FeNi films is determined from the magnetization curves and via magnetic torque measurements of the films. The obtained L10-FeNi film exhibiting a relatively high superlattice order parameter of 0.74 yielded a uniaxial magnetocrystalline anisotropy energy of ∼0.63 MJ/m3 at 300 K, as well as coercivities of 319 and 358 kA/m at 300 and 10 K, respectively. This coercivity is the highest value reported for artificial L10-FeNi to date.

Fabrication of N, O dual-doped ultra-microporous carbon from microalgae for efficient CO2 capture via deep eutectic solvent-assisted hydrothermal carbonization

A novel approach for porous carbon fabrication from microalgae is presented for efficient CO2 capture. Microalgae-derived hydrochar is produced through deep eutectic solvent-assisted hydrothermal carbonization (DES-HTC), followed by chemical activation to obtain N, O dual-doped ultra-microporous carbon. The finalized carbon exhibited high nitrogen content (3.92%), oxygen content (21.46%), and ultra-micropore volume (0.25 cm3/g). Subsequently, it exhibited excellent CO2 adsorption capacity (4.37 mmol/g) and CO2/N2 selectivity (32) at 25 °C and 1 bar. Equilibrium and in-situ FTIR spectra of CO2 adsorption substantiated that the synergy between the abundant oxygen and nitrogen functional groups and the ample ultra-micropores significantly enhanced the capacity. Characterization of hydrochar indicated that the addition of DES during HTC effectively accelerated the Maillard reaction, facilitating the insertion of nitrogen and oxygen atoms into the carbon matrix and reducing their loss in subsequent chemical activation. Furthermore, DES was found to increase thermally unstable oxygen functional groups during HTC, promoting in ultra-micropore formation during activation. These findings provide a framework for advancing microalgae-based carbon materials in CO2 capture applications.

SYNTHESIS OF UREA AND MAGNETITE-BASED CHITIN AS ADSORBENTS FOR THE REMOVAL OF AMLODIPINE BESYLATE

Objective: Development of urea and magnetite-based chitin adsorbents for the removal of amlodipine besylate. Methods: Amlodipine is a calcium channel blocker widely used to treat hypertension and angina. However, it is important to treat the residues before disposal so they do not pollute the effluent water sources. The amlodipine sorption property of chitin-based subtract (CBS) was improved by treatment with magnetite and urea, followed by pyrolysis at 500 °C. The FT-IR characterization, elemental composition, pore properties, and sorption isotherms were also assessed. Results: The sorption capacity of amlodipine increased from 4.6 to 9.3 mg/g for the urea and magnetite-treated products, respectively. Further, modified chitin products showed a pore volume (micro and mesopore composition), pore percentage, and roughness of 0.01 cm3g-1, 0.02 cm3g-1, 32% and 68%, and 1.2, respectively. The CBS and derivatives did not present Langmurian behavior, indicating a characteristic heterogeneous surface and the presence of energetically distinct sorption sites. The sorption equilibrium was achieved within 5 min, resulting in a net physical sorption. Conclusion: The insertion of nitrogen and iron moieties on the surface of chitin improved the adsorption capacity of amlodipine.

From Cycloalkanols to Heterocycles via Nitrogen Insertion.

A variety of cyclic alcohols are found to undergo nitrogen insertion by subjection to O-mesitylsulfonylhydroxylamine. Critical to a successful process is the use of fluorinated alcoholic solvents, which ensures sufficient substrate activation to allow engagement with the ambiphilic aminating agent. This transition-metal-free nitrogen insertion provides access to a variety of medicinally relevant heterocycles such as pyrrolidenes, quinolines, and benzazepines (24 examples). Furthermore, combination with a photochemical Norrish-Yang-type cyclization allows an unprecedented access to indoles from ortho-substituted acetophenones.

Programmable Amine Synthesis via Iterative Boron Homologation.

The value of Matteson-type reactions has been increasingly recognized for developing automated organic synthesis. However, the typical Matteson reactions almost exclusively focus on homologation of carbon units. Here, we report the detailed development of sequential insertion of nitrogen and carbon atoms into boronate C-B bonds, which provides a modular and iterative approach to access functionalized tertiary amines. A new class of nitrenoid reagents is uncovered to allow direct formation of aminoboranes from aryl or alkyl boronates via N-insertion. The one-pot N-insertion followed by controlled mono- or double-carbenoid insertion has been realized with widely available aryl boronates. The resulting aminoalkyl boronate products can undergo further homologation and various other transformations. Preliminary success on homologation of N,N-dialkylaminoboranes and sequential N- and C-insertions with alkyl boronates have also been achieved. To broaden the synthetic utility, selective removal of a benzyl or aryl substituent permits access to secondary or primary amine products. The application of this method has been demonstrated in the modular synthesis of bioactive compoundsand the programmable construction of diamines and aminoethers. A plausible reaction mechanism, supported by preliminary NMR (nuclear magnetic resonance) and computational studies, is also proposed.

Programmable Amine Synthesis via Iterative Boron Homologation

AbstractThe value of Matteson‐type reactions has been increasingly recognized for developing automated organic synthesis. However, the typical Matteson reactions almost exclusively focus on homologation of carbon units. Here, we report the detailed development of sequential insertion of nitrogen and carbon atoms into boronate C−B bonds, which provides a modular and iterative approach to access functionalized tertiary amines. A new class of nitrenoid reagents is uncovered to allow direct formation of aminoboranes from aryl or alkyl boronates viaN‐insertion. The one‐potN‐insertion followed by controlled mono‐ or double‐carbenoid insertion has been realized with widely available aryl boronates. The resulting aminoalkyl boronate products can undergo further homologation and various other transformations. Preliminary success on homologation ofN,N‐dialkylaminoboranes and sequentialN‐and C‐insertions with alkyl boronates have also been achieved. To broaden the synthetic utility, selective removal of a benzyl or aryl substituent permits access to secondary or primary amine products. The application of this method has been demonstrated in the modular synthesis of bioactive compounds and the programmable construction of diamines and aminoethers. A plausible reaction mechanism, supported by preliminary NMR (nuclear magnetic resonance) and computational studies, is also proposed.