Journal of Chemical Research

Four series of novel 1,3-thiazin(thiazol)-4-one derivatives were synthesized by Suzuki coupling. Preliminary bioassays showed that most of the synthesized compounds exhibited good inhibitory activity in vivo against root-knot nematodes, Meloidogyne spp. at 20 mg L⁻¹. Among the tested compounds, we found that two compounds displayed 46.4% and 41.4% inhibitory activity even at 1 mg L⁻¹, respectively.

A new asymmetrical Schiff base ligand, N¹-(3-((pyridin-2-ylmethylene)amino)propyl)ethane-1,2-diamine, and its copper(II) complex, [Cu(PPEA)Br]Br·H₂O (1), have been prepared. The copper complex has an elongated square pyramidal geometry with a CuN₄Br environment. The thermodynamic stability of the compounds and their charge distribution patterns were studied by Density Functional Theory and natural bond orbital analysis. The ability of the ligand and its copper complex to interact with 10 selected biomacromolecules (BRAF kinase, CatB, DNA gyrase, HDAC7, rHA, RNR, TrxR, TS, Top II and B-DNA) was investigated by docking studies and compared with that of doxorubicin.

The 1,2,3-triazole and 1H-1,2,3-benzotriazole-substituted 6,7-dihydroindolizin-8(5H)-one derivatives were synthesized by the reaction of (E)-7-(arylmethylidene)-6,7-dihydroindolizin-8(5H)-ones with 1,2,3-triazole and 1H-1,2,3-benzotriazole in the presence of Selectfluor in moderate yield. The structures of all the products were characterized thoroughly by nuclear magnetic resonance, infrared, and high-resolution mass spectrometry together with X-ray crystallographic analysis.

The binuclear silver(I) complex [Ag₂(η²-SPPh₃)₂(SPPh₃)₂](BF₄)₂ has been synthesized. Crystal analysis shows the coordination sphere around Ag(I) can be described as a three-coordinated slightly distorted planar triangular configuration with both monodentate and monoatomic bidentate bridging coordination modes for the SPPh₃ ligand. The fluorescence properties of free SPPh₃ and the Ag(I) complex have been studied in the solid state. The Ag(I) complex shows quasi-reversible Ag⁺/Ag pairs in its electrochemistry and has significant antioxidant activity against hydroxyl radicals.

A highly efficient heterogeneous palladium-catalyzed transfer semihydrogenation of internal alkynes was achieved in dimethylformamide at 145 ºC by using an MCM-41-immobilized bidentate nitrogen palladium(II) complex [MCM-41-2N-Pd(OAc)₂] as catalyst and dimethylformamide/KOH as hydrogen source, yielding a variety of cis-alkenes in good to high yields with excellent stereoselectivity. This supported palladium catalyst can be easily recovered by filtration of the reaction solution and recycled up to seven times with almost consistent activity.

Chemoselective reduction of β-enamino esters with NaBH(OAc)₃ promoted by MgI₂ etherate affords the corresponding β-amino esters in excellent yields in a short time under mild conditions.

Benzofuro[3,2-d]pyrimidine derivatives are prepared using aza-Wittig reactions of iminophosphoranes with n-butyl isocyanate at 40–50 °C to give carbodiimide intermediates, which are reacted with nitrogen-oxygen-containing nucleophiles to give 3-alkyl-2-amino (aryloxy/alkoxy)-benzofuro[3,2-d]pyrimidin-4(3H)-ones in satisfactory yields in the presence of a catalytic amount of sodium ethoxide or K₂CO₃. The iminophosphorane also reacts directly with excess carbon disulfide, followed by n-propylamine; further reaction with alkyl halides or halogenated aliphatic esters in the presence of anhydrous K₂CO₃ produces the corresponding 2-alkylthio-3-n-propyl-benzofuro[3,2-d]pyrimidin-4(3H)-ones in good yields. Their structures of the products are confirmed by ¹H NMR, ¹³C NMR, mass spectrometry, infrared and elemental analysis.

By using PCl₃ as the chlorinating reagent, various carboxylic acids are converted into the corresponding acid chlorides in good yields. This method features high atom efficiency in which nearly all three chlorine atoms of PCl₃ are used in the chlorination. Moreover, the work-up procedure is simple since the major side product is phosphonic acid [HP(O)(OH)₂] which is non-toxic and easily removed by filtration. A possible mechanism is proposed in this paper.

Glycol dicarbonate is successfully synthesized via transesterification of glycol with dimethyl carbonate. A catalyst screening is performed by studying the effect of acidity and alkalinity on the catalytic performance. The results indicate that compared with acidic catalysts, high conversions and yields are obtained with basic catalysts. Ca(OH)₂, with medium-strength alkalinity, exhibits excellent catalytic activity with glycol dicarbonate yields of 95%-99% when using a fractionation reaction system.