Abstract:: Phenanthridine and quinazolinone derivatives, as heterocyclic scaffolds, are highly valuable in pharmaceuticals, agriculture, and materials science. The phenanthridine ring system is a key structural motif found in numerous bioactive natural and synthetic compounds with diverse biological activities, including potent anticancer, antituberculosis, antitrypanosomal, antihepatitis, and pesticidal effects. Similarly, quinazolinones constitute a well-established class of heterocycles present in natural products such as dictyoquinazol A, bouchardatin, and luotonin A. Quinazolinones are considered privileged scaffolds in medicinal chemistry, exhibiting a broad spectrum of pharmacological activities, including anticancer, anti-inflammatory, antihypertensive, antidiabetic, antimicrobial, antimalarial, and analgesic effects. Compounds combining quinazoline and phenanthridine frameworks have also shown potential as electroluminescent materials and organic dyes. Although numerous synthetic approaches exist for constructing phenanthridine or quinazolinone/imine cores individually, phenanthridine- fused quinazolinone/imine systems remain relatively unexplored. Given their structural relevance in both biological and material applications, there is increasing demand for versatile, efficient synthetic strategies that integrate these scaffolds into a single molecular framework. This review highlights various catalytic methodologies for synthesizing 14H-quinazolino3,2-fphenanthridin-14- ones, starting from 2-phenylquinazolinone derivatives as key precursors. The catalytic approaches discussed include: Palladium-catalyzed transformations of unmasked 2-phenylquinazolin-4(3H)-ones, Ruthenium-catalyzed synthesis of 2,2-dimethyl-2,3-dihydro-4H-quinazolino3,2-fphenanthridine- 4,14(1H)-diones, Photocatalytic reactions employing 9-mesityl-10-methylacridinium perchlorate, and PIFA-mediated conversions. Additional methodologies cover palladium-catalyzed preparation of 14- imino derivatives from 2-(4-imino-3-phenyl-3,4-dihydroquinazolin-2-yl)anilines, palladium acetatecatalyzed formation of 8b,9-dihydro derivatives from bromophenyl-substituted quinazolinones, and generation of 14-iminium derivatives from 2-((1,1′-biphenyl-2-ylimino)methylene)amino) benzonitriles using SnCl4 or BF3·OEt2. These strategies may facilitate the discovery of novel bioactive compounds for medicinal applications and assist in designing more efficient functional materials.
Ameen et al. (Mon,) studied this question.