Capturing a Tetratomic Nitrogen Ring cyclo-N4 inside an Aza[ 82 ]fullerene

Synthesis of polymeric nitrogen compounds is a formidable task due to the proneness of nitrogen to the formation of N ≡ N triple bond, one of the strongest chemical bonds known. Here, we report an arc-discharge approach to successfully stabilize the elusive four-membered nitrogen ring (cyclo-N4) in an unprecedented endohedral metallofullerene Dy2N4@C81N (Dy-I). Its molecular structure has been unambiguously determined by X-ray crystallography to show a covalently bonded cyclo-N4 plane bridging two dysprosium ions inside an aza[82]fullerene cage, highlighting the stabilization of cyclo-N4 as a concurrent result of fullerene encapsulation and metal coordination. Our computational results further reveal a six-center-one-electron (6c-1e) bond delocalized over the inverse-sandwich Dy-N4-Dy cluster. This chemical peculiarity stems from the diffuse radical character of the highly anionic cyclo-N43− ligand, which is confirmed by electron paramagnetic resonance (EPR) spectrum of Y2N4@C81N (Y-I).

Synthesis and physicochemical studies of a series of mixed-ligand transition metal complexes and their molecular docking investigations against Coronavirus main protease

A novel series of mixed-ligand complexes of the type, [M(L1)(L2)Cl]·2H2O [L1 = 2-(α-methyl salicylidene hydrazine) benzimidazole (primary ligand), L2 = 2,2′-bipyridine (bipy; secondary ligand), M = Co(ii), Ni(ii), Cu(ii) and Zn(ii)], were based on the physicoanalytical studies. The spectroscopic findings revealed tridentate nature of the Schiff base ligand (L1) and its coordination to the metal ions via azomethine nitrogen, ring nitrogen and the deprotonated phenolic oxygen atoms. Furthermore, the synthesized compounds were evaluated for antimicrobial activity against Bacillus subtilis, Escherichia coli and Salmonella typhi microorganisms. In addition, molecular docking studies were carried out against Middle East respiratory syndrome coronavirus (PDB ID: 4ZS6) and severe acute respiratory syndrome coronavirus 2 main protease (PDB ID: 6W63).

Pericyclic Reactions in the Syntheses of Densely Functionalized Heterocylces

Background: Pericyclic reactions characterized by a cyclic transition state, have been established as a dominant approach for the synthesis of heterocyclic scaffolds owing to their tremendous efficacy, regioselectivity, and enantioselectivity. Pericyclic chemistry is a promising and creative route to various biologically significant five and six membered oxygen or nitrogen ring systems. Recognizing the reaction's potential, synthetic organic chemists have invested significant efforts in developing and applying a seemingly endless array of useful variations of pericyclic reactions. Objective: The driving force of this review is to focus the character of perfection and beauty inherent in these powerful reaction pathways that lead to unique and densely functionalized heterocylic assemblies. Conclusion: In this review, we have presented recent strategic applications of pericyclic reactions that provide quick access to molecular complexity with high efficiency. A summary of these illustrative examples will showcase the extensive role of pericyclic chemistry in the construction of synthetically intimidating structural motifs.

One-pot synthesis of highly functionalized pyrimido[1,2-b]indazoles via 6-endo-dig cyclization

An efficient synthesis of nitrogen ring junction pyrimido-indazoles has been developed.

UV-light induced domino type reactions: synthesis and photophysical properties of unreported nitrogen ring junction quinazolines

An expedient method for the synthesis of 5,6-dihydrobenzo[h][1,2,4]triazolo[5,1-b]quinazolines by UV light has been developed.