Synthesis of phenanthridinones using Cu- or Pd-mediated C N bond formation

TfOH-Catalyzed Cascade C-H/N-H Chemo-/Regioselective Annulation of Indole-2-carboxamides with Benzoquinones for the Construction of Anticancer Tetracyclic Indolo[2,3-c]quinolinones

An efficient TfOH-catalyzed cascade C-H/N-H annulation of indole-2-carboxamides with benzoquinones has been developed for the synthesis of tetracyclic indolo[2,3-c]quinolinones. This reaction exhibits excellent chemo-/regioselectivity, achieving functionalization of the C-3 of indole and N-H of the amide moiety to form the new C-C and C-N bonds. Various expected products were synthesized from readily available starting materials in good to high yields with a wide substrate scope and good functional group tolerance. Among all synthetic products, 3d showed the most potent cytotoxicity toward the 4T1 cancer cell line with an IC₅₀ value of 0.62 ± 0.05 μM. In vivo study demonstrated that 3d remarkably suppressed 4T1 xenograft tumor growth without body weight loss.

Copper-mediated C-O/C-N Bond Formation: A Facile Synthesis of 3-Amidocoumarin, 3-amidoazacoumarin and N-Aeroylindole Derivatives

Three different heterocyclic systems, 3-amidocoumarins 1, 3-amidoazacoumarins 11, and N-benzoylindol-2-carboxamides 12 were synthesized based on the strikingly different selectivity of copper-mediated C-O/C-N bond formation from azlactones under conventional heating conditions. The results demonstrated that the stereochemistry of the double bond dictated the outcome of the products. The microwave irradiation played an important role in the isomerization of the trisubstituted olefin leading to the formation of 3-amidocoumarins 1 and 3-amidoazacoumarins 11. Compounds 1h, 1i, and 1l showed promising to good cytotoxic activity against a panel of cancer cell lines including HepG2 (hepatoblastoma) and MOLT-3 (T-lymphoblast acute lymphoblastic leukemia).

Synthetic Strategies in the Preparation of Phenanthridinones

Phenanthridinones are important heterocyclic frameworks present in a variety of complex natural products, pharmaceuticals and displaying wide range of pharmacological actions. Its structural importance has evoked a great deal of interest in the domains of organic synthesis and medicinal chemistry to develop new synthetic methodologies, as well as novel compounds of pharmaceutical interest. This review focuses on the synthesis of phenanthridinone scaffolds by employing aryl-aryl, N-aryl, and biaryl coupling reactions, decarboxylative amidations, and photocatalyzed reactions.

Synthesis of Indolo[2,3-c]quinolin-6(7H)-ones and Antimalarial Isoneocryptolepine. Computational Study on the Pd-Catalyzed Intramolecular C-H Arylation

The synthesis of variously substituted indolo[2,3-c]quinolin-6(7H)-ones was developed via Pd-catalyzed intramolecular C-H arylation. This method highlights a strategy for preparing indoloquinoline precursors bearing versatile functional groups and provides a new approach for the synthesis of antimalarial isoneocryptolepine analogues. The plausible ring closure mechanism was examined with quantum chemical calculations, where a trigonal bipyramidal concerted metalation-deprotonation transition state is presumable.

Palladium-catalyzed decarbonylative annulation of phthalimides with arynes: direct construction of phenanthridinones

A novel palladium-catalyzed decarbonylative annulation between phthalimides and arynes was well-established, affording phenanthridinone derivatives in moderate to good yields.

Nickel-Catalyzed Oxidative Decarboxylative Annulation for the Synthesis of Heterocycle-Containing Phenanthridinones

A nickel-catalyzed oxidative decarboxylative annulation reaction of simple benzamides and (hetero)aromatic carboxylates has been developed. This reaction provides access to a large array of phenanthridinones and their heterocyclic analogues, highlighting the utility and versatility of oxidative decarboxylative coupling strategies for C-C bond formation.