Recent advances in the synthesis of highly substituted imidazolidines.

Imidazolidine is a saturated heterocycle with a cyclic aminal core that can be found in natural products and biologically active molecules. Additionally, these heterocyclic compounds have been utilized as chiral ligands, N-heterocyclic carbene precursors, and catalysts in organic synthesis. This review is an attempt to compile the literature of various synthetic procedures of highly substituted imidazolidines, chiral imidazolidines with high diastereoselectivities and enantioselectivities, bis-imidazolidines, and spiro-imidazolidines, as well as their pharmacological properties during the period from 1949 to 2023.

Recent advances in the transformation reactions of the Betti base derivatives.

Betti bases are the products resulting from the one-pot multicomponent reaction involving 1-naphthol/2-naphthol, aliphatic/aromatic aldehydes, and secondary amines. This chemical process is commonly referred to as the Betti reaction. The significance of Betti bases in medicinal chemistry has grown substantially due to their diverse array of pharmacological applications. Furthermore, their synthetic utility is considerable, given their use as catalysts and ligands in asymmetric synthesis. Moreover, Mannich products, incorporating diverse functional groups such as -OH and -NH, find application in a range of organic reactions. This utilization enables the synthesis of novel C-C bond linkages and diverse heterocycles, including biologically active naphthoxazines, which hold biological applications such as antibacterial, antifungal and anticancer. The focus of this review article is on the application of aminonaphthol derivatives in transformation reactions and the synthesis of organic compounds, with particular emphasis on heterocycles.

Design, synthesis, antimicrobial, antibiofilm evaluation and Z/E-isomerization of novel 6-((arylamino)methylene)benzo[a] phenazin-5(6H)-ones induced by organic solvent.

New 6-((arylamino)methylene)benzo[a]phenazin-5(6H)-one derivatives were synthesized, and good-to-high yields were achieved through one-pot, four-component condensation of 2-hydroxy-1,4-naphthoquinone, 1,2-phenylenediamine, aromatic amines and triethyl orthoformate using formic acid as catalyst under solvent-free conditions at 90 °C. The structure of these new compounds was confirmed using FT-IR and 1H-NMR as well as MS spectroscopy. Investigation of spectroscopy data indicated that the synthesized compounds exist in the keto-enamine tautomeric form and undergo Z/E-isomerization around the C[double bond, length as m-dash]C bond in DMSO-d6 at room temperature. Furthermore, intramolecular hydrogen bond has been observed in the synthesized E- and Z-ketoenamines. The noticeable features of the present procedure availability of starting materials, very simple operation, easy work-up, short reaction times, good to high yields and no need for column chromatography separation of benzophenazine enamines. The newly synthesized compounds were evaluated in vitro for their antibacterial, antifungal and antibiofilm activities against some of the tested microorganisms. The results demonstrated that compound 6b showed the maximum antibacterial activity, 6d exhibited the maximum antifungal activity and 6b had the most efficiency to inhibit biofilm formation of Bacillus subtilis (80%) at 200 µg mL-1 concentration.

Chemistry of 3-cyanoacetyl indoles: synthesis, reactions and applications: a recent update.

Indole is a significant nitrogen-based heterocycle with particular importance in the synthesis of heterocyclic scaffolds. Indole based compounds have been recently attracting much attention due to their biological and pharmaceutical activities. 3-Substituted indoles such as cyanoacetyl indoles (CAIs) are nitrogen-heterocyclic compounds which are easily obtained from the reaction of indoles and cyanoacetic acid. They are versatile starting materials utilized for the construction of a wide variety of molecules containing indole moieties in organic synthesis. In this study, we provide an overview on the synthesis of 3-cyanoacetyl indoles (CAIs) and their recent applications in the multi-component reactions for the synthesis of various heterocyclic compounds such as pyranes, pyridines, dihydropyridines, pyrimidines, tetrahydropyrimidines, pyrazoles, pyrazolopyridines, pyrazolopyrimidines, pyridopyrimidines, tetrazolopyrimidines, triazolopyrimidines, furans, dihydrofurans, coumarins, pyrimido naphthyridines, chromenes, thiazoles, pyrimidoindazoles, pyrazoloquinolines, isoxazolopyridines, and carbazoles and their biological activities during the period of 2013 to 2022.

A review on lawsone-based benzo[a]phenazin-5-ol: synthetic approaches and reactions.

Phenazine systems are an important class of aza-polycyclic compounds that are easily found in nature and isolated as secondary metabolites primarily from Pseudomonas, Streptomyces, and a few other genera from soil or marine habitats. Moreover, various synthetic phenazine analogs are known for their pharmaceutical activities. Among various phenazines, benzo[a]phenazines are structural subunits in a variety of important natural products and have been given special attention due to their unique biological properties in various fields. In this review article, we highlight the synthesis of benzo[a]phenazin-5-ol derivatives from lawsone and benzene-1,2-diamines and their applications for the construction of a variety of five and six membered fused heterocycles such as pyranophenazines, spiropyranophenazines, pyridophenazines, furophenazines, benzochromenophenazines and oxazinophenazines during the period of 1995 to 2021.

Platinum(II) complex with 4-nitro-N-(pyridin-2-ylmethylidene)aniline: synthesis, characterization, crystal structure and antioxidant activity.

A novel complex has been prepared using the (E)-4-nitro-N-(pyridin-2-ylmethylidene)aniline bidentate Schiff base ligand and PtCl2, namely, dichlorido[(E)-4-nitro-N-(pyridin-2-ylmethylidene)aniline-κ2N,N']platinum(II) acetonitrile hemisolvate, [PtCl2(C12H9N3O2)]·0.5CH3CN, 1. According to the X-ray measurements of the crystal structure, the PtII ion adopts a PtCl2N2 square-planar coordination. The coordination of the Schiff base ligand to the PtII ion occurs in a cyclic bidentate fashion, as a result of which a five-membered metallacycle is formed. Furthermore, in the structure of 1, the neutral molecules form a one-dimensional chain structure through C-H...Cl and C-H...O hydrogen bonds. The characterization of the complex was performed via single-crystal X-ray diffraction, IR spectroscopy and elemental analysis, and the antioxidant activity of the complex was evaluated using spectrophotometry by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method.

Dihydronaphthofurans: synthetic strategies and applications.

Dihydronaphthofurans (DHNs) are an important class of arene ring-fused furans which are widely found in many natural and non-natural products and drug candidates with relevant biological and pharmacological activities. Furthermore, vinylidene-naphthofurans exhibit photochromic properties when exposed to UV or sun light at room temperature. For these reasons, a vast array of synthetic procedures for the preparation of dihydronaphthofurans including annulation of naphthols with various reagents, cycloaddition reactions ([3 + 2], [4 + 1] and Diels-Alder), intramolecular transannulation, Friedel-Crafts, Wittig, Claisen rearrangement, neophyl rearrangement and other reactions under various conditions have been developed over the past decades. This review aims to describe the different strategies developed so far for the synthesis of dihydronaphthofurans and their applications. After a brief introduction to the types of dihydronaphthofurans and their biological activities, the different synthetic approaches such as chemical, photochemical, and electrochemical, methods are described and organized on the basis of the catalysts and the other reagents employed in the syntheses. The subsequent section focuses on biological and pharmacological applications and photochromic properties of the target compounds.

Correction: Recent advances in the synthesis and synthetic applications of Betti base (aminoalkylnaphthol) and bis-Betti base derivatives.

[This corrects the article DOI: 10.1039/C9RA02813G.].

Mannich bases derived from lawsone and their metal complexes: synthetic strategies and biological properties.

Lawsone (2-hydroxynaphthalene-1,4-dione) is a natural product which shows significant biological activity. Aminomethylnaphthoquinone Mannich bases derived from lawsone constitute an interesting class of naphthoquinones and/or their metal complexes have demonstrated a series of important biological properties. So, this review aimed to document the publications concerning the synthesis of aminomethylnaphthoquinone Mannich bases from lowsone, aldehydes and amines and their metal complexes using different conditions, and investigation of their applications.

Recent advances in the synthesis and synthetic applications of Betti base (aminoalkylnaphthol) and bis-Betti base derivatives.

The multicomponent reaction between 2-naphthol, arylaldehydes and ammonia yields aminobenzylnaphthols in a process known as the Betti reaction, which was first uncovered at the beginning of the 20th century. Various methods have been reported for the synthesis of aminobenzylnaphthol (Betti base) and bis-Betti base derivatives using various types of naphthols, aromatic amines, heteroaromatic amines, and aliphatic and cyclic amines instead of ammonia or diamines and aliphatic and aromatic aldehydes or dialdehyde compounds under various conditions in recent years. The Betti reaction produces racemic and non-racemic aminobenzylnaphthol ligands. It is also clear that the most important area of application of the non-racemic aminonaphthols prepared in this manner is their use in asymmetric synthesis, either as chiral ligands or as chiral auxiliaries. The functional groups in these Mannich products offer many ring closure possibilities. Some of these products or the starting bifunctional compounds possess biological activity. Herein, we present a selection of the relevant studies on this topic.

Al2O3 nanoparticles: an efficient and recyclable nanocatalyst for the rapid synthesis of N-heteroaryl formamides under solvent-free conditions.

A series of N-heteroaryl formamides were efficiently synthesized from heteroarylamines and formic acid using Al2O3 nanoparticles as a heterogeneous catalyst under solvent-free conditions. The smaller size of Al2O3 nanoparticles with a higher surface to volume ratio has a promising catalytic activity, resulting in a short reaction times and high reaction yields under mild reaction conditions. The catalyst could be recycled and reused four times without a noticeable decrease in its activity.