Ce immobilized 1H-pyrazole-3,5-dicarboxylic acid (PDA) modified CoFe2O4: A potential magnetic nanocomposite catalyst towards the synthesis of diverse benzo[a]pyrano[2,3-c]phenazine derivatives

A new DES-mediated synthesis of Henna-based benzopyranophenazines and benzoxanthenetriones

MTPPBr/THFTCA-DES was prepared as a new deep eutectic solvent (DES) from a mixture (molar ratio 7:3) of methyltriphenyl-phosphonium bromide (MTPPBr) and tetrahydrofuran-2,3,4,5-tetra-carboxylic acid (THFTCA), and characterized with various spectroscopic techniques, densitometer, and eutectic point. Then, it was used as a new and powerful catalyst for the synthesis of two sets of biologically important compounds, namely the Henna-based benzopyranophenazines and benzoxan-thenetriones. Solvent-free conditions, short reaction time, high efficiency, and easy recycling and separation of the DES catalyst are among the most important features of the presented method. Also, there is a nice consistency between the proposed structure of the DES compound, the integration values of the 1H NMR peaks, and the ratio of MTPPBr to THFTCA obtained from the eutectic point phase diagram. In addition, the reduction of peak splitting patterns in DES compared to the two primary materials can be good evidence of the formation of hydrogen bonds between the two components.

Melamine phosphate-modified magnetic chitosan: a novel biocompatible catalyst for the synthesis of biological tetrahydrodipyrazolopyridine and pyrazolopyranopyrimidine derivatives

A novel biocompatible composite was fabricated by the functionalization of magnetic chitosan with the melamine phosphate (MP) ionic compound to serve as a recoverable and bifunctional catalyst, aiming at the diversity-oriented generation of biological tetrahydropyrazolopyridine and pyrazolopyrimidine derivatives. This involved a meticulously orchestrated reaction, exploiting the in situ generated pyrazole alongside aromatic aldehydes, ammonium acetate, and (thio) barbituric acid. The present work manifests outstanding advantages, offering a novel and great method for the optimal synthesis of two valuable heterocyclic series especially five new derivatives. The resulting novel biocompatible composite was comprehensively characterized through a range of analytical techniques, including FT-IR, NH3 and CO2-TPD, XRD, TEM, FE-SEM, VSM, EDX, elemental CHNS analysis, ICP-MS, and NMR spectroscopy. Notably, the study represents a critical step in the preparation of advanced materials from accessible and cost-effective precursors.

Design and characterization of an urea-bridged PMO supporting Cu(II) nanoparticles as highly efficient heterogeneous catalyst for synthesis of tetrazole derivatives

In this work, a new periodic mesoporous organosilica with urea-bridges produced by the reaction of (3-aminopropyl)triethoxysilane and toluene-2,4-diisocyanate (APS-TDU-PMO) is introduced. The obtained APS-TDU-PMO was found to be an appropriate support for loading of Cu(II) nanoparticles to afford supramolecular Cu@APS-TDU-PMO nanocomposite. Uniformity and mesoporosity of both synthesized nanomaterials including APS-TDU-PMO and Cu@APS-TDU-PMO were proved by different spectroscopic, microscopic or analytical techniques including FTIR, EDX, XRD, FESEM, TEM, BET, TGA and DTA. Furthermore, the prepared Cu@APS-TDU-PMO nanomaterial was also used, as a heterogeneous and recyclable catalyst, for the synthesis of tetrazole derivatives through cascade condensation, concerted cycloaddition and tautomerization reactions. Indeed, the main advantages of this Cu@APS-TDU-PMO is its simple preparation and high catalytic activity as well as proper surface area which enable it to work under solvent-free conditions. Also, the introduced Cu@APS-TDU-PMO heterogeneous catalyst showed good stability and reusability for six consecutive runs to address more green chemistry principles.

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.