Homologous Design and Three-Dimensional Quantitative Structure-Activity Relationship Study of Acaricidal 2,4-Diphenyloxazolines Containing Different Heteroatoms and Alkyl Chains.

In order to speculate the three-dimensional structure of the potential binding pocket of the chitin synthase inhibitor, a series of 2,4-diphenyloxazoline derivatives with different lengths of alkyl chains and heteroatoms were designed and synthesized by a homologous strategy. The bioassay results indicate that both the length of the alkyl chains and the type of substituents can affect the acaricidal activity against mite eggs. Compounds containing chloropropyl, alkoxyalkyl, and para-substituted phenoxyalkyl or phenylthioalkyl groups exhibit good activity, while those containing steric hindrance substituents or carbonyl substituents on the benzene ring exhibit reduced activity. Three-dimensional quantitative structure-activity relationship (3D-QSAR) study showed that there may be a narrow hydrophobic region deep in the pocket, and the steric effect plays a more important role than the electrostatic effect. The current work will provide assistance for future molecular design and target binding research.

Design, Synthesis, Acaricidal Activities, and Structure-Activity Relationship Studies of Oxazolines Containing Ether Moieties.

To develop highly efficient and low cost acaricides, a series of 2,4-diphenyl-1,3-oxazolines containing an ether moiety at the para position of the 4-phenyl group were synthesized from different alcohols and phenols. The bioassay results showed that most of the compounds, especially the short-chain alkyl ethers, exhibited excellent acaricidal activity against both the larvae and the eggs of Tetranychus cinnabarinus. In particular, the n-propyl ether compound Ic possessed much better larvicidal activity (LC50 = 0.0015 mg/L) and ovicidal activity (LC50 = 0.0008 mg/L) than commercial acaricide etoxazole (LC50 = 0.0145 and 0.02 mg/L for larvae and eggs, respectively). In addition, some compounds also exhibited insecticidal activity, especially compound Iw (4-CF3-phenyl ether) showed higher mortality than etoxazole against Mythimna separata, Helicoverpa armigera, and Pyrausta nubilalis. Considering the high acaricidal activity and relatively low cost, Ic was worthy of further study as an acaricide agent. An alternative synthetic route for the large-scale synthesis of Ic was then studied.

Palladium Metallaphotoredox-Catalyzed 2-Arylation of Indole Derivatives.

Given that biaryl motifs are found in many useful molecules, including pesticides, pharmaceuticals, functional materials, and polymers, the development of methods for their construction is important. Herein, we report a two-step method for C(sp2)-H/C(sp2)-H cross-coupling reactions to synthesize 2-arylindole derivatives by combining palladium catalysis and photocatalysis. This mild, dual-catalysis method showed good functional group tolerance and a wide substrate scope and could be used for late-stage functionalization of oligopeptides, drugs, and natural products.

Diverse Oxidative C(sp2)-N Bond Cleavages of Aromatic Fused Imidazoles for Synthesis of α-Ketoamides and N-(pyridin-2-yl)arylamides.

An efficient and chemoselective C(sp2)-N bond cleavage of aromatic imidazo[1,2- a]pyridine molecules is developed. A broad scope of amide compounds such as α-ketoamides and N-(pyridin-2-yl)arylamides are afforded as the final products in up to quantitative yields. Diverse C-N bond cleavages are controlled by the oxidative species used in this transformation, with various amide products afforded in a chemoselective fashion. A preliminary study indicated that some α-ketoamides exhibit anti-Tobacco Mosaic Virus activity for potential use in plant protection.