CuI/Proline-catalyzed N-Arylation of Nitrogen Heterocycles

Ma＇s CuI/proline procedure for the catalytic cross coupling between nitrogen heterocycles and aryl halides was markedly improved. The key finding was that K3PO4 was a much better base than K2CO3 for the reaction. With this new reaction condition the cross coupling with aryl iodides could be accomplished in 1,4-dioxane instead of DMSO. This reactin also could be carried out in DMF. Furthermore, the coupling yields under the new conditions are usually higher than in Ma＇s original methods.

A Pd(Ⅱ)-Catalyzed Oxidative Cyclization for the Preparation of AryI-Fused Six-Membered Nitrogen Heterocycles with 2-Acetoxy Functionality

A Pd（II）-catalyzed oxidative cyclization of olefinic tosylamides was developed for the preparation of aryl-fused and N-containing six-membered heterocycles. Under optimized conditions the reaction proceeded with high activity and selectivity, with yields of up to 83% being obtained. This procedure provides a facile and efficient route to the aforementioned heterocycles with 2-acetoxy functionality.

Cis-and Trans-Coordination Assembly of Nitrogen Heterocycle with Copper(Ⅱ) and Silver(Ⅰ)

After the preparation of 1,4-bis（4,5-dihydro-lH-imidazol-2-yl）benzene（bdib）, a nitrogen heterocycle with potential coordination manners of both cis- and trans-configuration forms, three complexes, including cis-[Cuz（bdib ）2（/L-OCH3）2]Cl2·2MeOH（1）, trans-[Cu（bdib）（AcO）2]n（2）, and cis-[Ag2（bdib）2]（NO3）2.2H20（3）, were successfully self-assembled. Complexes 1 and 2 crystallized in the monoclinic system with P21/n space group and complex 3 in the triclinic system with P1 space group.

Design, Synthesis, Chemistry and Biological Evaluation of Some Polyfunctional Heterocyclic Nitrogen Systems—Overview

The synthesis, preparation, chemical reactivities and biological activity of simple heterocyclic and heteropolycyclic nitrogen systems as small units as functional pyrazoles, pyridine and pyrimidine, and the related fused systems are reviewed. Among the various possible routes to the formation, isomeric structures have been cited because of patented reaching advanced phases of clinical trials, from 2000 to 2020.

3,6-bis(2,2,2-trinitroethylnitramino)-1,2,4,5-tetrazine.Structure and energy abilities as a component of solid composite propellants

The work addresses to the study of the molecular and crystal structure and properties of a new energyintensive compound 3,6-bis(2,2,2-trinitroethylnitramino)-1,2,4,5-tetrazine(NBTAT),first obtained by the authors in 2020.NBTAT compound crystallizes in the monoclinic system,space group P2(1)/n,density at room temperature 1.939 g/cm^(3).The energies of crystal packing and pairwise intermolecular interactions in NBTAT and its unnitrated analogue BTAT were calculated,and their comparative analysis was carried out.The enthalpy of formation of NBTAT molecules was calculated by quantum-chemical methods using Gaussian 09,and the enthalpy of formation of NBTAT in the solid phase(618 kJ/mol)was estimated.The energy capabilities of NBTAT as an oxidizer of solid composite propellants are estimated.It is shown that in metal-free compositions NBTAT is significantly superior to ammonium perchlorate(AP),dinitramide ammonium salt(ADN),HMX,BTAT at all stages of rocket systems,and is comparable to the superdense CL-20 yielding to the latter at the lower stages and slightly winning at the upper stages.

A New Polynitrogen-Heterocyclic Scaffold 2,4,6,8-Tetraazanoradamantane Skeleton:Synthesis and Conversion of Its Functionalities

Comprehensive Summary 2,4,6,8-Tetraazanoradamantane skeleton is a unique rigid cage-like organic structure that has not been established.In this article,a facile protocol to build all-bridge-position-functionalized 2,4,6,8-tetraazanoradamantane skeleton by condensation of glyoxal,primary amines and disubstituted malondialdehydes,which were in situ generated from 2,2-dipropenyl-1,3-dioxolane or 4,4-dimethoxyhepta-2,5-diene via ozonation,is reported for the first time.A variety of primary amines are compatible with this process,and the corresponding 2,4,6,8-tetraalkyl-2,4,6,8-tetraazanoradamantane-9-one ethylene or methyl ketals were achieved in 16%—58%yields.N-Benzyl group could be converted to other functionalities such as acetyl and nitro,which indicates the structural diversity of this scaffold.

Design and Synthesis of Novel 5-Sulfoxide-substituted Pyrazolo[5,1-d][1,2,3,5]tetrazin-4(3H)ones

A series of novel 5-sulfoxide-substituted pyrazolo[5,1-d] [1,2,3,5]tetrazin-4（3H）ones 4a-j were designed and efficiently synthesized via a diazotization of 5-amine-3-methylsulfinyl- 1H-pyrazole, followed by cycloaddition with aryl isocyanate. A possible reaction mechanism is outlined and discussed. These new compounds exhibit some biological activity as preliminary bioassay indicated. Their structures were confirmed with ^1H NMR, IR and elemental analysis.

Asymmetric Hydrogenation of Phenanthridines with Chiral Boranes

The asymmetric hydrogenation of N-heteroarenes provides an efficient method for the synthesis of optically active cyclic secondary amines.In this paper,we described an asymmetric hydrogenation of phenanthridines using a chiral mono-alkene-derived borane.A variety of dihydrophenanthridines were furnished in high yields with up to 93%ee.The current catalytic system was very sensitive for the steric hindrance of phenanthridines.Bulky substituents at one phenyl group of phenanthridines were required to obtain the high enantioselectivity.But large substituents on the carbon of the C=N bonds would diminish the reactivity sharply.

1,3-Dipolar Cycloaddition of Polycyclic Aromatic Azomethine Ylides and Alkynylbenziodoxoles for Synthesis of Functional Dibenzoullazines

A new family of dibenzoullazine derivatives was synthesized through 1,3-dipolar cycloaddition of polycyclic aromatic azomethine ylides with alkynylbenziodoxoles followed by oxidation.The benziodoxole moiety in the resulting products was used as a versatile linchpin for the synthesis of structurally diverse functional dibenzoullazines that are difficult to access by other synthetic methods.

Phosphine-Catalyzed [4+3] Annulation Reaction of Indole Derivatives with MBH Carbonates:A Facile Access to Indole-1,2-fused 1,4-Diazepinones and Azepines

A phosphine-catalyzed [4+3] annulation between dinucleophilic indole derivatives and Morita−Baylis−Hillman (MBH) carbonates was discovered by using the N1 and N4′/C4′ nucleophilicities of the indole precursors,in which indoles act as four atom synthons. This protocol provides an efficient and facile access to indole-1,2-fused 1,4-diazepinones and azepines in good to high yields in one step,which illustrates potential synthetic utilities in drug discovery.

Recent advances in visible-light photoredox-catalyzed nitrogen radical cyclization

Visible-light photoredox catalysis is a powerful and attractive strategy for organic molecule activation and new reaction design owing to its environmental-friendly characteristics and unique catalytic mechanisms,and has found wide applications in organic synthesis.This catalytic strategy enables controllable generation of diverse nitrogen-centered radicals(NCRs)under mild conditions,providing access to construction of diverse nitrogencontaining compounds.In this review,we critically illustrate the recent advances in the field of visible-light photoredox-catalyzed cyclization of nitrogen-centered radicals,based on the different radical precursors and activation modes.Wherever possible,particular emphasis is also put on working models and synthetic applications.

Rare-earth,nitrogen-rich,oxygen heterocyclic supramolecular compounds(Nd,Sm,and Eu):Synthesis,structure,and catalysis for ammonium perchlorate

Three novel rare-earth,nitrogen-rich and oxygen heterocyclic supramolecular complexes,namely[Nd(BTF)_(2)(H_(2)O)_(5)]_(n),[Sm(BTF)_(2)(H_(2)O)_(5)]_(n),and[Eu(BTF)_(2)(H_(2)O)_(5)]_(n),were synthesized.A single crystal was obtained by the solvent evaporation method,and the structure and coordination mode of metal complexes were determined by single crystal X-ray diffraction.Results show that the supramolecular complexes contain many hydrogen bonds and thus have good thermal stability(T_(dec)>540 K).The thermal decomposition of ammonium perchlorate(AP)catalyzed by the complexes was investigated by differential thermal analysis,which reveals a pre-eminent catalytic effect on AP.The high temperature decomposition peak of AP can be advanced by nearly 90 K at the amount of added complexes of 10 wt%,and the activation energy of AP descent range is from 70 to 150 kJ/mol.The other properties were fully characterized through elemental analysis and Fourier transform infrared spectroscopy.

Palladium-Catalyzed Cyclization Reaction of o-Haloanilines, CO2 and Isocyanides： Access to Quinazoline-2,4（1H,3H）-diones

Quinazoline-2,4（1H,3H）-diones are core structural subunits frequently found in many biologically important compounds. The reaction of 2- aminobenzonitrile and CO2, which was frequently studied, only provided N3-unsubstituted quinazoline-2,4（1H,3H）-dione compounds. Herein we report palladium-catalyzed cyclization reactions of o-haloanilines, CO2 and isocyanides to prepare N3-substituted quinazoline-2,4（1H,3H）-diones. Electron-rich o-bromoanilines participated in the cyclization reaction using Cs2CO3 at high temperature, and electron-deficient o-bromoaniline or o-iodoaniline sub- strates conducted the reaction using CsF as base to deliver corresponding quinazoline-2,4（1H,3H）-dione products in good yields.

MCM-41-SO3H as a Highly Efficient Sulfonic Acid Nanoreactor for the Rapid and Green Synthesis of Some Novel Highly Substituted Imidazoles under Solvent-Free Condition

Nanosized MCM-41-SO3H based on ordered mesoporous silica material with a covalent sulfonic acid group was synthesized and used as acid catalyst for the new, simple, convenient and green synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetra-substituted imidazoles. Also some of synthesis products are new. Echo-friendly protocol, short reaction times, easy and quick isolation of the products and excellent yields are the main advantages of this procedure.

Recent Developments in Azide-Free Synthesis of 1,2,3-Triazoles

1,2,3-Triazoles, as one of the most significant nitrogen-containing heterocycles due to their extensive use in biology, material science and organic synthesis, have aroused great interest, 1,2,3-Triazoles are commonly synthe- sized by metal-catalyzed azide-alkyne cycloaddition and organocatalytic azide-carbonyl cycloaddition, which indispensably employ the toxic and potentially explosive azides. The azide-free synthetic approaches provide a powerful and straightforward alternative to the assembly of diverse 1,2,3-triazoles without the use of azides. In this review, we summarize the recent development of the construction of 1,2,3-triazoles under azide-free conditions.

Highly Site-and Enantioselective N-H Functionalization of N-Monosubstituted Aniline Derivatives Affording Pyrazolones Bearing a Quaternary Stereocenter

Chiral phosphoric acid catalyzed the regio-and enantioselective N-H functionalization of N-alkylaniline with pyrazolones derived ketimines as electrophiles,providing a variety of chiral pyrazolones containing a tetrasubstituted stereocenter bearing a new N,N'-acetal motif in excellent yields and high enantioselectivities.This strategy was featured by low catalyst loading,mild conditions,and high efficiency and selectivity.

Cu-Catalyzed Chemoselective Reduction of N-Heteroaromatics with NH_(3)·BH_(3) in Aqueous Solution

An efficient catalytic system was successfully developed on reduction of A/-heteroaromatics with H3N-BH3 as hydrogen source in CuSO4 solution,featuri ng excel I e nt chemoselectivity as well as very broad functional group tolera nee.Various challe nging substrates,such as OH-,NH_(2)^(-), Cl^(-),Br^(-),etc.,contained quinolines,quinoxalines,1,5-naphthyridines and quinazolines were all reduced smoothly.Mecha nistic studies suggested that[Cu-H]in termediate might be gen erated from NH_(3)·BH_(3)/which was believed to form with H3N-BH3 in CuSO_(4) solution.

Thermal Behaviors of 2-（Dinitromethylene）-1,3- diazacycloheptane （DNDH）

2-（Dinitromethylene）-1,3-diazacycloheptane （DNDH） was prepared by the reaction of 1,1-diamino-2,2-dinitro- ethylene （FOX-7） with 1,4-diaminoethane in NMP. Thermal decomposition behavior of DNDH was studied under the non-isothermal conditions with DSC method, and presents only one intensely exothermic decomposition process The kinetic equation of the decomposition reaction is da/dT= 103388× 3a2/3exp（--3.353 ×10^5/RT）/fl. The critical temperature of thermal explosion is 215.97℃. Specific heat capacity of DNDH was studied with micro-DSC method and theoretical calculation method, and the molar heat capacity is 215.40 Jomol-1,K-1 at 298.15 K. Adiabatic time-to-explosion was calculated to be 92.07 s. DNDH has same thermal stability to FOX-7.

Copper-catalyzed N-Arylation of Imidazoles with Aryl or Heteroaryl Halides Facilitated by Dimethylglyoxime in Water

A combination of CuSO4/dimethylglyoxime was found to be an efficient and inexpensive catalyst system for N-arylation of imidazole and benzimidazole with aryl halides and heteroaryl halides in water, providing the corresponding products in moderate to good yields.

Bischler-Napieralski Cyclization:A Versatile Reaction towards Functional Aza-PAHs and Their Conjugated Polymers

Nitrogen atom doped polycyclic aromatic hydrocarbons,the so-called aza-PAHs,and their conjugated polymers are applicable as functional chromophores and organic semiconductors.Prosperous developments of PAHs and heterocyclic chemistry have been made possible by considerable improvements in synthetic methodologies,among which one-step reactions leading directly to an aza-conjugated ring are highly desirable.Bischler-Napieralski cyclization,an old yet efficient reaction,can accomplish this task.During the last ten years,this reaction has been successfully used to synthesize a great variety of aza-PAHs molecules.Further combination with polymer chemistry is able to provide the corresponding polymers.This feature article summarizes the up-to-data advances,mainly achieved by our groups,on the design and synthesis of new and well-tailored aza-PAHs and macromolecular architectures using Bischler-Napieralski cyclization as the key step.Furthermore,the versatile applications of these functional materials in the fields of chemosensors,optoelectronic devices,and biomolecular probes are also covered in detail.