Palladium nanoparticles for the synthesis of phenanthridinones and benzo[c]chromenes via C-H activation reaction

In the present work, derivatives of phenanthridine-6(5H)-ones and benzo[c]chromenes were efficiently prepared through an intramolecular C-H bond functionalization reaction catalyzed by photochemically synthesized Pd-PVP nanoparticles. The heterocycles were obtained via intramolecular arylation of the corresponding N-methyl-N-aryl-2-halobenzamide or aryl-(2-halo)benzyl ethers using K2CO3 as base in a mixture of H2O : DMA as solvent without additives or ligands. High yields of the heterocyclic compounds were achieved (up to 95%) using a moderately low catalyst loading (1-5 mol%) under an air atmosphere at 100 °C. The reaction exhibited very good tolerance to diverse functional groups (OMe, Me, t Bu, Ph, OCF3, CF3, F, Cl, -CN, Naph), and both bromine and iodine substrates showed great reactivity. Finally, the in vitro antiproliferative activity of phenanthridine-6(5H)-ones and benzo[c]chromenes was evaluated against six human solid tumor cell lines. The more active compounds exhibit activity in the low micromolar range. 1-Isopropyl-4-methyl-6H-benzo[c]chromene was identified as the best compound with promising values of activity (GI50 range 3.9-8.6 μM). Thus, the benzochromene core was highlighted as a novel organic building block to prepare potential antitumor agents.

Well-defined Cu(I) complexes based on [N,P]-pyrrole ligands catalyzed a highly endoselective 1,3-dipolar cycloaddition

We herein report the synthesis and catalytic application of a new family of dinuclear Cu(I) complexes based on [N,P]-pyrrole ligands. The Cu(I) complexes (4a-d) were obtained in good yields and their catalytic properties were evaluated in the1,3-dipolar cycloaddition of azomethine ylides and electron-deficient alkenes. The air-stable complexes 4a-d exhibited high endo-diasteroselectivity to obtain substituted pyrrolidines, and the catalytic system showed excellent reactivity and wide substitution tolerance.

Comparative Analysis of the Donor Properties of Isomeric Pyrrolyl Phosphine Ligands

Understanding the net donor and electronic properties of pyrrole-based phosphines is critical for guiding their use as ligands. In this study, we compare two isomeric 1- and 2-(diphenylphosphino)methylpyrroles (L1 and L2, respectively) to determine the degree to which N-(phosphino)pyrroles are distinct from aryl- and 2-pyrrolyl phosphines. Ruthenium, rhodium, platinum, and gold complexes as well as selenide derivatives of these ligands are examined using NMR and IR spectroscopy, X-ray crystallography, and cyclic voltammetry. Ligand L2 exhibits net donor properties similar to those of the o-tolyl analogue L3, while L1 shows attenuated electron donation ability. Additionally, a model nickel-catalyzed Kumada coupling reaction using these three ligands was investigated.

DNA Binding and Anticancer Properties of New Pd(II)-Phosphorus Schiff Base Metal Complexes

DNA has become the target of metal complexes in cancer drug discovery. Due to the side effects of widely known cisplatin and its derivative compounds, alternative metal-based drug discovery studies are still ongoing. In this study, the DNA-binding ability of Pd(II) and Pt(II) complexes of four phosphorus Schiff base ligands and four hydrazonoic-phosphines are investigated by using in silico analyses. Phosphorus Schiff base-Pd(II) complexes encoded as B1 and B2 with the best DNA-binding potential are synthesized and characterized. The DNA-binding potentials of these two new Pd(II) complexes are also investigated experimentally, and their antitumor properties are demonstrated in vitro in A549, MCF7, HuH7, and HCT116 cancer cells. The mechanisms of these metal complexes that kill the cells mentioned above in different activities are elucidated by flow cytometry apoptosis analysis and colony formation analysis The in silico binding energies of these two new palladium complexes ΔG (B1): −4.51 and ΔG (B2): −6.04 kcal/mol, and their experimental DNA-binding constants were found as Kb (B1): 4.24 × 10⁵, Kb (B2): 4.98 × 10⁵). The new complexes, which show different antitumor effects in different cells, are the least effective in HuH7 liver cells, while they showed the best antitumor properties in HCT116 colon cancer cells.

Oxidant-Free C(sp2)-H Functionalization/C-O Bond Formation: A Kolbe Oxidative Cyclization Process

An anodic oxidation/cyclization of 2-arylbenzoic acids for the synthesis of dibenzopyranones has been developed. The reaction proceeds at room temperature with no oxidant or electrolyte required and exhibits a high atom economy with H₂ being the only byproduct. A series of dibenzopyranones was obtained in good to excellent yields. Urolithins A, B, and C are formally synthesized by adopting this method as a key step to demonstrate its synthetic utility.

Palladium-catalyzed intramolecular C–H arylation of 2-halo-N-Boc-N-arylbenzamides for the synthesis of N–H phenanthridinones

A palladium catalyzed synthesis of N–H phenanthridinones was developed via C–H arylation. The protocol gives phenanthridinones regioselectively by one-pot reaction without deprotection. It exhibits broad substrate scope and affords targets in up to 95% yields. Importantly, it could be applied for the less reactive o-chlorobenzamides.

Pd(t-Bu₃P)₂/KOAc proved to be a good combination for one-pot synthesis of N–H phenanthridinones with up to 95% yield.