A new route to podolactones functionalized in the A ring has been achieved. Two key steps were employed in this synthesis, the construction of the bicyclic skeleton via a Mn(III)-mediated radical cyclization and the transformation of this bicyclic intermediate into the tetracyclic podolactone skeleton through a Pd (II)-mediated bislactonization of the corresponding conjugate diene. The reported synthesis of 3beta-hydroxy-13,14,15,16-tetranorlabda-7,9(11)-dien-(19,6beta),(12,17)-diolide (1) let us reassign the structure of wentilactone B, for which structure 1 was wrongly reported. [reaction: see text] 相似文献
The mononuclear vanadium(Ⅴ) complex with 2-hydroxyl-1-naphthaldehyde isoncotinoyl hydrazone was synthesized and characterized by single-crystal X-ray diffraction.The crystal is of monoclinic,space group P2 1/n with a = 10.3153(15),b = 7.4024(11 ),c = 24.413(4) (A),β= 101.911(2)°,V= 1824.0(5) (A)3,Z = 4,Mr = 427.28,Dc = 1.556 g/cm3,F(000) = 880,μ(MoKα) =0.591,the final R = 0.0372 and wR = 0.0926.The vanadium(Ⅴ) atom adopts a distorted square-pyramidal geometry coordinated by the tridentate ligand and two oxygen atoms.The hydrogen bonds and strong π…π stacking interactions link the complex molecules into a 3-D network structure. 相似文献
A novel high-yielding Zn/CuI-mediated coupling method of alkyl halides with vinyl sulfones, vinyl sulfonates, and vinyl sulfonamides is described. This protocol is applicable for primary, secondary, and tertiary alkyl iodides and bromides. Alkyl chlorides and aryl and vinyl halides were unreactive under the reaction conditions. Formamide was found to be a superior solvent for obtaining high yields. 相似文献
The nucleus-independent chemical shifts (NICS), anisotropy of the induced current density (AICD), and molecular orbital (MO) analyses demonstrated the non-aromaticity of the β-diketiminate-coordinated Ae compounds. The DFT calculations revealed relatively high isomerization energies (ISE) for β-diketiminatecoordinated Ae compounds, which contribute to their stability. 相似文献
Hydrophilic and hydrophobic deep eutectic solvents (DESs) as “green” solvents were applied in this study for the microextraction of environmental samples. A series of DESs (five hydrophilic and three hydrophobic) were synthesized and characterized by Fourier transform infrared spectroscopy. Physicochemical property parameters of eight DESs including water solubility, density, conductivity, and freezing point were assessed. Compared with the performance of five hydrophilic DESs in water phase, the three hydrophobic DESs were more suitable for application in dispersive liquid-liquid microextraction for the determination of sulfonamides in water sample. In dispersive liquid-liquid microextraction process, analytical parameters including type and volume of extraction solvent, extraction time, and pH of water sample were investigated. Under optimum conditions, 60 μL of hydrophobic DESs was used for extraction for 2 min in pH = 7.0 sample. The linear ranges were 0.05–5.0 μg/mL for the four sulfonamides with the correlation coefficients in the range of 0.9991–0.9999. The limits of detection were in the range of 0.0005–0.0009 μg/mL and the limits of quantification were in the range of 0.0019–0.0033 μg/mL. The recoveries of the analytes of the proposed method for the spiked samples were 80.17–93.5%, with the relative standard deviation less than 6.31%. The results indicated that three hydrophobic DESs showed commendable performance for extraction of sulfonamides, and hydrophobic DES-based microextraction method was successfully applied for monitoring sulfonamides in water samples.