Nitrogen-containing Framework Research Articles

Sulfonamides with Heterocyclic Periphery as Antiviral Agents.

Sulfonamides are the basic motifs for a whole generation of drugs from a large group of antibiotics. Currently, research in the field of the new sulfonamide synthesis has received a "second wind", due to the increase in the synthetic capabilities of organic chemistry and the study of their medical and biological properties of a wide spectrum of biological activity. New reagents and new reactions make it possible to significantly increase the number of compounds with a sulfonamide fragment in combination with other important pharmacophore groups, such as, for example, a wide class of N-containing heterocycles. The result of these synthetic possibilities is the extension of the activity spectrum-along with antibacterial activity, many of them exhibit other types of biological activity. Antiviral activity is also observed in a wide range of sulfonamide derivatives. This review provides examples of the synthesis of sulfonamide compounds with antiviral properties that can be used to develop drugs against coxsackievirus B, enteroviruses, encephalomyocarditis viruses, adenoviruses, human parainfluenza viruses, Ebola virus, Marburg virus, SARS-CoV-2, HIV and others. Since over the past three years, viral infections have become a special problem for public health throughout the world, the development of new broad-spectrum antiviral drugs is an extremely important task for synthetic organic and medicinal chemistry. Sulfonamides can be both sources of nitrogen for building a nitrogen-containing heterocyclic core and the side chain substituents of a biologically active substance. The formation of the sulfonamide group is often achieved by the reaction of the N-nucleophilic center in the substrate molecule with the corresponding sulfonylchloride. Another approach involves the use of sulfonamides as the reagents for building a nitrogen-containing framework.

Direct Synthesis of CF2H-Substituted 2-Amidofurans via Copper-Catalyzed Addition of Difluorinated Diazoacetone to Ynamides.

The significance of molecules containing difluoromethyl groups is driven by their potential applications in pharmaceutical and agrochemical science. Methods for the incorporation of lightly fluorinated groups such as CF2H have been less well developed. Here we report the use of difluorinated diazoacetone as a practical reagent for the direct synthesis of CF2H-substituted 2-amidofurans through addition to ynamides. These newly designed difluorinated amidofurans were elaborated to create new nitrogen-containing frameworks that would be challenging to obtain otherwise.

Efforts towards Rh(II)-catalyzed N-alkoxyazomethine ylide generation: Disparate reactivities of O-tethered α-diazo keto and -β-ketoester oximes

Abstract Azomethine ylide [3 + 2]-cycloaddition reactions are among the most powerful and well-studied chemical transformations to construct five-membered nitrogen-containing frameworks. However, cycloadditions of azomethine ylides bearing N-alkoxy substituents have largely been overlooked. This has been the case despite the potential for (1) accessing heterocycles with good regio- and diastereocontrol, (2) the presence of a cleavable tether which can be manipulated downstream via N–O bond cleavage, and (3) the promise of interesting structural diversity. Herein, we describe our efforts toward dirhodium-catalyzed intramolecular N-alkoxyazomethine ylide generation from α-diazoketo and -β-ketoester oximes and the disparate reactivities observed.

Tert-Butyl Nitrite (TBN), a Multitasking Reagent in Organic Synthesis.

The upsurge interest in the development of efficient methodologies for the construction of nitrogen-containing frameworks via the use of expedient reagents have been creating a renaissance in contemporary organic chemistry. In this perspective, tertbutyl nitrite (TBN) is an emerging building block. Due to its unique structural features, it shows differential reactivity under different reaction conditions. These diverse reactivities have resulted in the construction of a diverse array of complex N-containing molecules. The primary objective of the present review is to bring the latest findings of TBN in terms of its applications in reactions (oxidation, diazotization, nitrosation, nitration, oximation, N-synthon, and miscellaneous reactions) into the limelight. For simplicity and brevity, reactions in each section are explained with the mechanism of formation and selected examples are given.

Synthesis of mechanically robust porous carbon monoliths for CO2 adsorption and separation

Abstract Porous carbon materials with developed porosity, high surface area and good thermal- and chemical-resistance are advantageous for gas adsorption and separation. However, most carbon adsorbents are in powder form which exhibit high pressure drop when deployed in practical separation bed. While monolithic carbons have largely addressed the pulverization problem and preserved kinetics and usually suffer from abrasion during multiple adsorption-desorption cycles. Herein, we proposed the designed synthesis of mechanically robust carbon monoliths with hierarchical pores, solid nitrogen-containing framework. The synthesis started with the polymerization of resorcinol and formaldehyde under weakly acidic conditions generated from cyanuric acid, and then an appropriate amount of hexamethylenetetramine (HMTA) was added as a crosslinker to prompt the formation of three dimensional frameworks. After carbonization process, the as-obtained porous carbon monoliths have a high radial compressive strength of 886 N/cm as well as a BET specific surface area of up to 683 m2/g. At approximately 1 bar, the CO2 equilibrium capacities of the monoliths are in the range of 3.1–4.0 mmol/g at 273 K and of 2.3–3.0 mmol/g at 298 K, exhibiting high selectivity for the capture of CO2 over N2 from a stream which consists of 16.7% (v%) CO2 in N2. Meanwhile, they undergo a facile CO2 release in an argon stream at 298 K, indicating a good regeneration capacity. After cycle testing, sieving and regeneration, the adsorbent has no mass loss, compared to that of its fresh counterpart.

A Rational Design of Microporous Aerogel for Excellent CO2 Capture and Selectivities via Co-Synergistic Effects of Electrostatic In-plane and π–π Stacking Interactions

Microporous aerogel (PEINK) with a nitrogen-containing framework, high CO2 capture and selectivity were obtained through the condensation polymerization of 1,3,5-tris-(4-fluorobenzoyl)benzene with 5-hydroxyindol. The uptake capacity for CO2 reached up to 17.7 wt % (1.0 bar, 273 K), and the high CO2/N2 = 16, CO2/CH4 = 29 selectivity. Density functional theory illustrated that a CO2 molecular was captured via synergistic efforts with π–π stacking of indole group and electrostatic in-plane binding of an adjacent ether unit, thus the selectivity and adsorption of CO2 were strengthen. The proposed co-synergistic effect on one CO2 molecular is expected to be a new theory for the design of high CO2 capture materials.

Ketenimines Generated from Ynamides: Versatile Building Blocks for Nitrogen-Containing Scaffolds.

Using ynamides as readily available starting materials, a single step can generate highly reactive ketenimines, which can then undergo a variety of transformations. The choice of the method for generating the ketenimine dictates the outcome of the reaction that can, moreover, be precisely steered through minor variations of the starting material. This Concept gives an overview of the different existing methodologies for this objective, showcasing the diverse nitrogen-containing frameworks that can be obtained by this highly versatile strategy.

Fabrication of porous carbon monoliths with a graphitic framework

Macro/mesoporous carbon monoliths with a graphitic framework were synthesized by carbonizing polymeric monoliths of poly(benzoxazine-co-resol). The overall synthesis process consists of the following steps: (a) the preparation of polymeric monoliths by co-polymerization of resorcinol and formaldehyde with a polyamine (tetraethylenepentamine), (b) doping the polymer with a metallic salt of Fe, Ni or Co, (c) carbonization and (d) the removal of inorganic nanoparticles. The metal nanoparticles (Fe, Ni or Co) formed during the carbonization step catalyse the conversion of a fraction of amorphous carbon into graphitic domains. The resulting carbon monoliths contain >50wt.% of graphitic carbon, which considerably improves their electrical conductivity. The use of tetraethylenepentamine in the synthesis results in a nitrogen-containing framework. Textural characterization of these materials shows that they have a dual porosity made up of macropores and mesopores (∼2–10nm), with a BET surface area in the 280–400m2g−1 range. We tested these materials as electrodes in organic electrolyte supercapacitors and found that no conductive additive is needed due to their high electrical conductivity. In addition, they show a specific capacitance of up to 35Fg−1, excellent rate and cycling performance, delivering up to 10kWkg−1 at high current densities.

Structurally Designed Synthesis of Mechanically Stable Poly(benzoxazine-co-resol)-Based Porous Carbon Monoliths and Their Application as High-Performance CO2 Capture Sorbents

Porous carbon monoliths with defined multilength scale pore structures, a nitrogen-containing framework, and high mechanical strength were synthesized through a self-assembly of poly(benzoxazine-co-resol) and a carbonization process. Importantly, this synthesis can be easily scaled up to prepare carbon monoliths with identical pore structures. By controlling the reaction conditions, porous carbon monoliths exhibit fully interconnected macroporosity and mesoporosity with cubic Im3m symmetry and can withstand a press pressure of up to 15.6 MPa. The use of amines in the synthesis results in a nitrogen-containing framework of the carbon monolith, as evidenced by the cross-polarization magic-angle-spinning NMR characterization. With such designed structures, the carbon monoliths show outstanding CO(2) capture and separation capacities, high selectivity, and facile regeneration at room temperature. At ~1 bar, the equilibrium capacities of the monoliths are in the range of 3.3-4.9 mmol g(-1) at 0 °C and of 2.6-3.3 mmol g(-1) at 25 °C, while the dynamic capacities are in the range of 2.7-4.1 wt % at 25 °C using 14% (v/v) CO(2) in N(2). The carbon monoliths exhibit high selectivity for the capture of CO(2) over N(2) from a CO(2)/N(2) mixture, with a separation factor ranging from 13 to 28. Meanwhile, they undergo a facile CO(2) release in an argon stream at 25 °C, indicating a good regeneration capacity.