On-line coupling of dynamic microwave-assisted extraction to solid-phase extraction for the determination of sulfonamide antibiotics in soil

A rapid technique based on dynamic microwave-assisted extraction (DMAE) coupled on-line with solid-phase extraction (SPE) was developed for the determination of sulfonamides (SAs) including sulfadiazine, sulfameter, sulfamonomethoxine and sulfaquinoxaline in soil. The SAs were first extracted with acetonitrile under the action of microwave energy, and then directly introduced into the SPE column which was packed with neutral alumina for preconcentration of analytes and clean-up of sample matrix. Subsequently, the SAs trapped on the alumina were eluted with 0.3% acetic acid aqueous solution and determined by liquid chromatography-tandem mass spectrometry. The DMAE parameters were optimized by the Box-Behnken design. Maximum extraction efficiency was achieved using 320 W of microwave power; 12 mL of extraction solvent and 0.8 mL min⁻¹ of extraction solvent flow rate. The limits of detection and quantification obtained are in the range of 1.4-4.8 ng g⁻¹ and 4.6-16.0 ng g⁻¹ for the SAs, respectively. The mean values of relative standard deviation of intra- and inter-day ranging from 2.7% to 5.3% and from 5.6% to 6.7% are obtained, respectively. The recoveries of SAs obtained by analyzing four spiked soil samples at three fortified levels (20 ng g⁻¹, 100 ng g⁻¹ and 500 ng g⁻¹) were from 82.6 ± 6.0% to 93.7 ± 5.5%. The effect of standing time of spiked soil sample on the SAs recoveries was examined. The recoveries of SAs decreased from (86.3-101.9)% to (37.6-47.5)% when the standing time changed from one day to four weeks.     

Self-assembly of aromatic sulfonamide-amide hybridized molecules: formation of 2D layers and 3D microporous networks in the solid state

Three sulfonamide-amide hybridized molecules and one cyclic analogue were synthesized and their assembling behaviors in the solid state were investigated by X-ray crystallography. The results showed that the hybridized molecules could be not only induced to take up helical secondary structures by a network of intramolecular hydrogen bonds, but also utilized as useful building blocks for assembling into 1D zigzag chains and superhelices, 2D layers and further 3D networks. Moreover, it was found that the multiple C-H?OS hydrogen bonds played an important role in the assembling processes.     

Fe(II)-catalyzed N-alkylation of sulfonamides with benzylic alcohols

The FeCl₂/K₂CO₃ catalyst system was developed successfully for the N-alkylation of sulfonamides with benzylic alcohols via borrowing hydrogen method. XPS analysis suggested a possible catalyst cycle between Fe(II) and Fe(0). Under the optimized condition, the scope of the protocol was demonstrated in 21 different alkylation reactions. High yields, in general >90%, are achieved in most cases.     

新型大环磺酰胺肽模拟物的设计及其关键前体的合成

动植物、微生物和病毒等都含有微量的环肽 ,其中大多具有明显的生理活性 ,因此 ,受到科学家们的高度重视 [1] .设计与合成具有生理活性的新型环肽是目前有机合成的前沿课题 [2～ 4 ] .烯烃复分解闭环反应 ( RCM)已成为构成碳环和杂环的重要手段 [5～ 7] .由于 Schrock和 Grubbs催化剂的高活性和官能基适用性 ,烯交换闭环反应已被应用于肽的合成 [8～ 10 ] .在研究通过烯交换闭环反应设计与合成新型肽化合物的基础上 [11] ,我们设计了通过烯交换闭环反应从含有两个末端烯双键化合物合成新型大环磺酰胺肽模拟物的新途径 ,如 Scheme 1 ,其中…     

Synthesis of chiral vicinal C2 symmetric and unsymmetric bis(sulfonamide) ligands based on trans-1,2-cyclohexanediamine by aminolysis of N-tosylaziridines

The ring opening of N-tosylaziridines with aliphatic amines can be efficiently catalyzed by lithium perchlorate to provide derivatives of the trans-1,2-diamine in high yields. The reaction was used in desymmetrization of several cyclic N-tosylaziridines using chiral amines. Using this strategy, an efficient synthesis of chiral vicinal C₂ symmetric bis(sulfonamide) and unsymmetrical bis(sulfonamide) ligands based on trans-1,2-cyclohexanediamine was developed.     

Electrochemical Synthesis and Characterization of Zinc(II) Complexes with [(4‐Methylphenyl)Sulfonyl]‐1H‐Amido‐2‐Phenyl‐2‐Oxazolines

A series of [(4‐methylphenyl)sulfonyl]‐1H‐amido‐2‐phenyl‐2‐oxazoline ligands, HTs‐ROz, has been synthesized by the reaction of substituted 2‐(2‐aminophenyl)oxazolines and p‐toluensulfonyl chloride. The electrochemical oxidation of a sacrificial zinc anode in an acetonitrile solution of the corresponding ligand gave compounds of general formula [Zn(Ts‐ROz)₂]. All complexes have been characterized by microanalysis, IR and ¹H NMR spectroscopy and single‐crystal X‐ray diffraction. In all cases, the metal atom is coordinated by the nitrogen atoms of two monoanionic ligands.     

Microwave assisted ring-opening of epoxides with N-biaryl sulfonamides in the synthesis of matrix metalloproteinase-9 inhibitors

A microwave accelerated epoxide ring-opening process with N-biaryl sulfonamides is described. Under this mild, highly efficient condition, an α-hydroxy-β-N-biaryl sulfonamide skeleton is rapidly assembled leading ultimately to a novel series of matrix metalloproteinase-9 inhibitors with single digit nanomolar activities.     

Efficient Large-Scale Synthesis of 2-Amino-5-methanesulfonylaminobenzenesulfonamide

A novel synthesis of 2-amino-5-methanesulfonylaminobenzenesulfonamide is described. This preparation begins with readily available 4-nitroaniline and proceeds through five steps (isolations) in 41% overall yield. The described chemistry is conducted on a 50- to 100-g scale and does not require extractive workup procedures or chromatographic purifications.