An efficient synthesis of novel spiro[benzo[c]pyrano[3,2-a]phenazines] via domino multi-component reactions using l-proline as a bifunctional organocatalyst

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.

One-pot multi-component synthesis of novel chromeno[4,3-b]pyrrol-3-yl derivatives as alpha-glucosidase inhibitors

A green and efficient one-pot multi-component protocol was developed for the synthesis of some novel dihydrochromeno[4,3-b]pyrrol-3-yl derivatives through the reaction of arylglyoxals, malono derivatives, and different 4-amino coumarins in ethanol at reflux condition. In this method, all products were obtained in good to excellent yield. Next, all synthesized derivatives were evaluated for their α-glucosidase inhibitory activity. Most of the compounds displayed potent inhibitory activities with IC₅₀ values in the range of 48.65 ± 0.01–733.83 ± 0.10 μM compared to the standard inhibitor acarbose (IC₅₀ = 750.90 ± 0.14 μM). The kinetic study of compound 5e as the most potent derivative (IC₅₀ = 48.65 ± 0.01 μM) showed a competitive mechanism with a K_i value of 42.6 µM. Moreover, docking studies revealed that dihydrochromeno[4,3-b]pyrrol-3-yl effectively interacted with important residues in the active site of α-glucosidase.

Expedient synthesis of novel antibacterial hydrazono-4-thiazolidinones under catalysis of a natural-based binary ionic liquid

A library of pyran-2H-one-3-ylmethylidene and chromene-2H-one-3-ylmethylidene derivatives of the titled heterocyclic framework was synthesized from 3-acyl-4-hydroxypyran/chromene-2H-one via sequential reaction with thiosemicarbazide and dialkyl acetylenedicarboxylates. The syntheses were carried out under efficient catalysis of a new binary ionic liquid mixture [L-prolinium chloride][1-methylimidazolium-3-sulfonate] in one pot and solvent-free conditions. Calculations based on density functional theory displayed that the barrier energy for interconversion of the two possible diastereomeric isomers of each product is less than the thermal energy of molecules at room temperature, as only one product can be resolved from a given reaction mixture. This seems to be the case for the previously reported hydrazonothiazolidines. The binary ionic liquid mixture melts at near room temperature and can be considered as a solution of HCl in 1:1 mixture of two zwitterionic species. It proved to be more efficient than its constituents in catalyzing the above synthesis in one-pot operation. Some of the synthesized products have shown pronounced antibacterial activities. The ionic liquid is virtually stable in air and moisture, as can be retrieved several times without appreciable decrease in its catalytic activity.

Green synthesis of novel spiro-indenoquinoxaline derivatives and their cholinesterases inhibition activity

A convenient synthesis of substituted spiroindenoquinoxalines at mild and green conditions was developed. Multicomponent reaction of substituted phenylene diamines, ninhydrin, malononitrile and N,N'-substituted-2-nitroethene-1,1-diamines produced the target compounds. Twelve new spiroindenoquinoxalines were obtained, and their ability in inhibition of acetyl and butyrylcholinesterases were investigated both in vitro and in silico. All compounds showed moderate level activity against both acetyl and butyrylcholinesterases.

Highly efficient, one-pot synthesis of novel bis-spirooxindoles with skeletal diversity via sequential multi-component reaction in PEG-400 as a biodegradable solvent

A green, efficient, multi-component protocol has been developed for synthesis of novel bis-spirooxindoles in short reaction time, easy workup and excellent yields.

Synthesis and evaluation of new chromene based [1,8]naphthyridines derivatives as potential antimicrobial agents

Novel chromeno[4,3-f][1,8]naphthyridines derivatives were prepared by multicomponent reaction between 2-((sub)amino)quinoline-3-carbaldehyde 1a–f/2a–f, ethyl 2-cyanoacetate 3 and cyclohexane-1,3-dione 4 in ethanol with l-proline as a catalyst.

A catalyst-free, one-pot multicomponent synthesis of spiro-benzimidazoquinazolinones via a Knoevenagel–Michael-imine pathway: a microwave assisted approach

A multi-component route for the synthesis of spiro-benzimidazoquinazolinones was developed and its mechanism was studied.

Montmorillonite K10 catalyzed multi component reactions (MCR): synthesis of novel thiazolidinones as anticancer agents

Montmorillonite K10 is a suitable catalyst in a multicomponent reaction involving an aldehyde, an amine, and thioglycolic acid in N,N-dimethylformamide as solvent at moderate (50°C) to reasonably high (120°C) temperatures to form thiazolidinones. The reaction involves easy workup and purification. Several thiazolidinones were prepared. In particular, campholenic aldehyde obtained from α-pinene was used to synthesize potentially bioactive thiazolidinones. All products were characterized by IR, 1H NMR, and mass spectra. Preliminary anticancer screening tests revealed that two compounds show anticancer activity and can be taken up for further screening.

Sulfanilic acid-functionalized silica-coated magnetite nanoparticles as an efficient, reusable and magnetically separable catalyst for the solvent-free synthesis of 1-amido- and 1-aminoalkyl-2-naphthols

Sulfanilic acid-functionalized silica-coated magnetite nanoparticles as an efficient, reusable and magnetically separable catalyst for the solvent-free synthesis of 1-amido- and 1-aminoalkyl-2-naphthols.

Recyclable Bi2WO6-nanoparticle mediated one-pot multicomponent reactions in aqueous medium at room temperature

Room temperature multicomponent reactions (MCRs) are reported using Bi₂O₃, BiVO₄, and Bi₂WO₆ (nanoparticle) as heterogeneous catalysts. Among these, Bi₂WO₆ (5 mol%) nanoparticles showed excellent reactivity for the synthesis of functionalized dihydropyridine, polyhydroquinoline, 4H-chromene and 2-amino-4H-benzo[b]pyran derivatives in aqueous medium.

Electrogenerated base-promoted synthesis of 5-aryl-5,6-dihydro-2H-pyrano[2,3-d]pyrimidine-2,4,7-triones by multicomponent assembly of barbituric acid, aldehydes and Meldrum's acid at room temperature

An electrochemical strategy for the synthesis of pyrano[2,3-d]pyrimidine-2,4,7-triones via a one-pot, three component condensation is described.