Recent Advances in Catalytic Synthetic Routes for Quinazolino [3, 2-f] Phenanthridin-14-one Derivatives Derived From 2-Arylquinazolinones: A Review

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-quinazolino[3,2-f]phenanthridin-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-quinazolino[3,2-f]phenanthridine- 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.