Gold(III)‐Catalyzed Intermolecular Oxidation‐Cyclization of Ynones: Access to 4‐Substituted Chroman‐3‐ones

Construction of Chalcogenated Methylene Chroman-3-ones via Palladium-Catalyzed Carbocyclization

We report herein the synthesis of exo-chalcogenated methylene chroman-3-ones via palladium-catalyzed intramolecular acyl-chalcogenation of alkyne with thio- and selenoesters. Chalcogen containing tetrasubstituted alkenes are obtained stereoselectively. This protocol tolerates various functional groups and heterocycles, affording the chroman-3-one products in moderate-to-good yields.

A Chemoenzymatic Cascade Combining a Hydration Catalyst with an Amine Dehydrogenase: Synthesis of Chiral Amines

An encapsulated gold carbene complex was combined with a free amine dehydrogenase (GkAmDH) as a co-catalyst, enabling a cascade synthetic route to directly access chiral amines from propargylethers. This process, combining an initial gold carbene catalyzed hydration of propargylethers to ketones followed by a subsequent reductive amination, produces a wide range of chiral amines in high yields and excellent enantioselectivities.An encapsulated gold carbene complex was combined with a free amine dehydrogenase (GkAmDH) as a co-catalyst, enabling a cascade synthetic route to directly access chiral amines from propargylethers. This process, combining an initial gold carbene catalyzed hydration of propargylethers to ketones followed by a subsequent reductive amination, produces a wide range of chiral amines in high yields and excellent enantioselectivities.

Synthesis and biological evaluation of novel steroidal pyrazole amides as highly potent anticancer agents

A series of thirty-six steroidal pyrazole amides, divided into two categories based on their main skeletons were designed and synthesized via a five-step synthetic route. The final product is obtained through Pinnick oxidation of pyrazole aldehydes to yield the corresponding acids, which then underwent amidation to afford the target products efficiently under mild reaction conditions. Structures of the desired compounds were confirmed by ¹H NMR, ¹³C NMR, high resolution mass spectrometry; X-ray structural characterization of compound 16n was also obtained. The synthesized compounds were screened for their antiproliferative activity against four cancer cell lines (Pc-3 A549, Hela, HepG2) using the SRB method. Amides 10n, 16n, and 16p-16t exhibited moderate to high cytotoxic activities with IC₅₀ values ranging from 2.05 to 8.73 μM. Of note, the hydrochloride derivative 16p displayed the highest activity towards PC-3 cells with IC₅₀ values of 2.05 μM. Analysis of structure-activity relationships indicated that the presence of the diamine moiety and the aqueous solubility of the derivatives were vital factors for antiproliferative potency. Furthermore, molecule 16p induced PC-3 cells apoptosis and arrested cell cycle at G1 phase in a dose-dependent manner.

Gold(I)-Catalyzed Oxidative Amination of β-Amino-ynones to Quaternary Ammonium-olate Salts: The Benefit of a P,N-Bidentate Ligand

A novel P,N-bidentate ligand-assisted gold-catalyzed oxidative amination of β-amino-ynones has been developed, allowing the simple and efficient construction of various quaternary ammonium-olate salts in good to excellent yields. These unprecedented quaternary ammonium-olate salts can be isolated and purified via simple suction filtration. The broad substrate scope, easy purification, easy further transformation, and mild conditions make it a viable alternative for the synthesis of various quaternary ammonium-olate salts.

Phosphine-Catalyzed Synthesis of 3-Allyl-4-pyrones by the Tandem Reaction of Diynones and Allylic Alcohols

A simple and effective tandem reaction of diynones and allylic alcohols was developed to afford functionalized 3-allyl-4-pyrones in moderate to excellent yields. This protocol underwent a Michael addition─Claisen rearrangement─O-cyclization process, which exhibited broad substrate tolerance, high regioselectivity, and atom economy under a metal-free condition. Moreover, functional transformation of the products was also further studied.

Design, Synthesis, and Study of the Insecticidal Activity of Novel Steroidal 1,3,4-Oxadiazoles

A series of novel steroidal derivatives with a substituted 1,3,4-oxadiazole structure was designed and synthesized, and the target compounds were evaluated for their insecticidal activity against five aphid species. Most of the tested compounds exhibited potent insecticidal activity against Eriosoma lanigerum (Hausmann), Myzus persicae, and Aphis citricola. Compounds 20g and 24g displayed the highest activity against E. lanigerum, showing LC₅₀ values of 27.6 and 30.4 μg/mL, respectively. Ultrastructural changes in the midgut cells of E. lanigerum were detected by transmission electron microscopy, indicating that these steroidal oxazole derivatives might exert their insecticidal activity by destroying the mitochondria and nuclear membranes in insect midgut cells. Furthermore, a field trial showed that compound 20g exhibited effects similar to those of the positive controls chlorpyrifos and thiamethoxam against E. lanigerum, reaching a control rate of 89.5% at a dose of 200 μg/mL after 21 days. We also investigated the hydrolysis and metabolism of the target compounds in E. lanigerum by assaying the activities of three insecticide-detoxifying enzymes. Compound 20g at 50 μg/mL exhibited inhibitory action on carboxylesterase similar to the known inhibitor triphenyl phosphate. The above results demonstrate the potential of these steroidal oxazole derivatives to be developed as novel pesticides.

Synthesis of sorafenib analogues incorporating a 1,2,3-triazole ring and cytotoxicity towards hepatocellular carcinoma cell lines

A series of 1,2,3-triazole-containing Sorafenib analogues, in which the aryl urea moiety of Sorafenib (1) was replaced with a 1,2,3-triazole ring linking a substituted phenoxy fragment, were prepared successfully via Huisgen 1,3-dipolar cycloaddition and nucleophilic aromatic substitution. The studies of cytotoxicity towards human hepatocellular carcinoma (HCC) cell lines, HepG2 and Huh7, indicated that p-tert-butylphenoxy analogue 2m showed significant inhibitory activity against Huh7 with IC₅₀ = 5.67 ± 0.57 µM. More importantly, 2m showed low cytotoxicity against human embryonal lung fibroblast cell line, MRC-5, with IC₅₀ > 100 µM, suggesting its highly selective cytotoxic activity (SI > 17.6) towards Huh7 which is much superior to that of Sorafenib (SI = 6.73). The molecular docking studies revealed that the analogue 2m bound B-RAF near the binding position of Sorafenib, while it interacted VEGFR2 efficiently at the same binding position of Sorafenib. However, 2m exhibited moderate inhibitory activity toward B-RAF, implying that its anti-Huh7 effect might not strictly relate to inhibition of B-RAF. Wound healing and BrdU cell proliferation assays confirmed anti-cell migration and anti-cell proliferative activities towards Huh7. With its inhibitory efficiency and high safety profile, 2m has been identified as a promising candidate for the treatment of HCC.

Gold(iii)-catalyzed bicyclizations of alkylidenecyclopropane-tethered ynones for divergent synthesis of indene and naphthalenone-based polycycles

A gold(iii)-catalyzed cascade oxidation/cyclization of alkylidenecyclopropane-tethered ynones for the assembly of indene and naphthalenone-based polycycles by employing different N-oxides is reported.

Alkynyl- and phosphine-ligated quaternary Au2Ag2 clusters featuring an Alkynyl-AuAg motif for multicomponent coupling

The coordination motif of alkynly with a metal atom is versatile and plays a pivotal role in tailoring the kernel configuration of the atomically precise metal nanoclusters. In this study, we synthesized a new mono-valent Au(I)₂Ag(I)₂(C₁₀H₆NO)₄(Ph₃P)₂ alloy cluster with a very high yield of >90%, which is well characterized by a serial of technologies, e.g. UV-vis, X-ray single crystal diffraction (SCXRD) and FT-IR. The SCXRD analysis shows the alloy cluster is composed of a quadrangular Au₂Ag₂ kernel protected by four alkynyl and two phosphine ligands. Intriguingly, a new divergent alkyne-metal coordination model is revealed in this cluster, the alkynyl ligands selectively bind to Au and Ag atoms via σ- and π-bond configurations and adopt a VI-shaped alkynyl-M motif. It is distinct from the convergent motif observed in big clusters featuring an IV- or V-shaped alkynyl-M motif due to the steric effect. Finally, the titanium oxide-supported Au₂Ag₂ cluster catalysts show good catalytic performance in the multicomponent coupling reaction of alkynes, aldehydes and amines.

The coordination motif of alkynly with a metal atom is versatile and plays a pivotal role in tailoring the kernel configuration of the atomically precise metal nanoclusters.