Group 4 metallocenes in bioorganometallic chemistry

Group 4 metallocene complexes can form adducts or condensation products with a variety of typical biogenic molecules. In this account, examples are presented and discussed for the reactions of zirconocene or titanocene complexes with suitably protected/deprotected carbohydrate derivatives. Some methodological developments are shown for the attachment of aminoacid or peptide derived functional groups at the Cp-rings of the Group 4 bent metallocenes. Eventually, the reactions of methylzirconocene- and methyltitanocene cations with a series of short oligopeptides are discussed that lead to the formation of primary κO-adducts followed by O,N,O-chelate complex formation with methane evolution. The dynamic features of some such systems are discussed.     

Applications of multifunctional magnetic nanoparticles for the enrichment of proteins for PAGE separation

This paper describes the applications of multifunctional magnetic nanoparticles (MNPs) for the enrichment of low‐abundance proteins for polyacrylamide gel electrophoresis (PAGE) separation. The hemoglobin‐functionalized MNPs, named Hb–MNPs, were obtained based on electrostatic interactions and covalent binding between the hemoglobin (Hb) and the MNPs. It was demonstrated that the proteins in human serum were selectively conjugated to Hb‐MNPs, which can be used for the selective enrichment of low‐abundance proteins. Three and seven kinds of proteins were identified by MS after 1‐D and 2‐D PAGE, respectively. Comparing with native PAGE without the treatment of MNPs, some proteins were observed, such as human serum amyloid P component (SAP), vitamin D‐binding protein, and serine peptidase inhibitor. Because the high concentration of SAP can be considered as a signal for the neurodegeneration of Alzheimer's disease, the present Hb‐MNPs‐based method was applied to investigate the serum level of SAP for the diagnosis of Alzheimer's disease, and the results are satisfying.     

Efficient synthesis of functionalized 6-arylsalicylates via microwave-promoted Suzuki cross-coupling reaction

Functionalized 6-arylsalicylate substructures occur in a variety of pharmacologically relevant natural products and bioactive compounds. They are also broadly used as important intermediates in organic synthesis. Traditional synthetic methods have suffered from some drawbacks, such as relatively harsh reaction conditions, narrow range of substrates, and poor yields. Utilizing microwave irradiation, the synthesis of functionalized 6-arylsalicylates via a Suzuki cross-coupling has been developed with a wide range of substrates. Almost all the reactions proceeded smoothly and afforded moderate to excellent yields of products, which indicated that electronic effects and steric modifications have little effect on this reaction.     

Three-component synthesis of novel trifluoromethyl-containing tetrahydropyran derivatives

l-Proline-catalyzed reaction of ethyl 4,4,4-trifluoroacetoacetate, cinnamaldehyde and anilines provide a novel method for preparation of ethyl-6-(arylamino)-2-hydroxy-4-phenyl-2-(trifluoromethyl)tetrahydro-2H-pyran-3-carboxylate derivatives in good yields. The reaction was conducted by initial Michael addition, followed by intra-molecular cyclization under mild conditions. The structure of a typical ethyl-2-hydroxy-4-phenyl-6-(m-tolylamino)-2-(trifluoromethyl)tetrahydro-2H-pyran-3-carboxylate (4h) was confirmed by XRD analysis. A plausible mechanism is presented.     

Synthesis and desilylation of some bis(trimethylsilyl)alkenes and polymers bearing bis(silyl)alkenyl groups

The synthesis of various vinylbis(silanes) from some aryl and heteroaryl aldehydes and (Me₃Si)₃CLi in Et₂O is described. Friedel-Crafts reaction of 1,1-bis(trimethylsilyl)-2-(2-naphthyl)ethene with various acyl chlorides (RCOCl, R = Me, Et, i-Pr, i-Bu, n-pent) gave the corresponding α-silyl-α,β-unsaturated enones with high E steroselectivity. Moreover, poly(styrene)-co-[2,2-bis(trimethylsilyl)ethenyl(styrene)] obtained via the reaction of polymers bearing pendant enone functions and (Me₃Si)₃CLi, reacts with the same acyl chlorides in the presence of catalytic amount of AlCl₃ to give the new macromolecules bearing α-silyl-α,β-unsaturated enones and α,β-unsaturated enones.     

An effective new access to ethyl 2-[(alkylamino)(cyano)methyl] acrylates: first synthesis of ethyl 3-cyano-2-(hydroxymethyl) acrylate

A regioselective coupling of ethyl 2-(bromomethyl)-3-cyanoacrylate and primary amines is described to give ethyl 2-[(alkylamino)(cyano)methyl] acrylates in good yields. Whereas the conversion of allyl bromide in the presence of TEAF leads to the first synthesis of ethyl 3-cyano-2-(hydroxymethyl) acrylate.     

An efficient route to pyridine and 2,2′-bipyridine macrocycles incorporating a triethylenetetraminetetraacetic acid core as ligand for lanthanide ions

Two novel macrocyclic chelators L₁ and L₂ incorporating an intracyclic pyridine or 2,2′-bipyridine unit and a triethylenetetraminetetraacetic acid core (TTTA) were synthesized with the aim of forming lanthanide complexes suitable as efficient long-lived luminophores. For this goal, an efficient methodology for the preparation of TTTA derivatives using prealkylated precursors is described. Starting from commercially available compounds, the target ligands were obtained in seven (L₁) and nine (L₂) steps in 40% and 20% overall yields, respectively. Stable Tb(III) complexes were prepared and displayed interesting luminescence properties.     

反应性聚烯烃的分子设计、催化聚合及应用

通用高分子材料高性能化研究的一个主要内容是聚烯烃(聚乙烯和聚丙烯)的高性能化和功能化.但是,由于聚烯烃大分子的化学惰性,其化学(分子)改性和物理(材料)改性都存在很大困难.近年来,烯烃聚合催化剂技术不断进步,烯烃聚合理论研究持续深入,从而为通过分子设计手段以可控方式在聚烯烃中引入化学活泼基团而制备结构明确和组成均匀的反应性聚烯烃奠定了基础.本文从反应性聚烯烃的分子设计、催化聚合以及其在聚烯烃高性能化研究中的应用等几个方面综述了近年来反应性聚烯烃领域的研究进展,并对此领域今后的研究发展方向提出了建议.     

Preparation of functionalized magnetic nanoparticulate sorbents for rapid extraction of biphenolic pollutants from environmental samples

A new solid-phase extraction coupled with magnetic carrier technology was developed for extraction of bisphenol A (BPA) and diethylstilbestrol (DES) from water samples. The SPE sorbents, functionalized magnetic nanoparticles (Fe₃O₄@SiO₂/β-CD, core/shell), were synthesized in a two-stage system. The material was characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, and a vibrating sample magnetometer. SPE extraction parameters, such as volume and pH of sample, adsorption time, and desorption conditions were optimized. Under selected conditions: 250 mL of water sample, 0.1 g of sorbents and elution with methanol (3 mL with 1% acetic acid), the extraction was completed in 25 min. SPE followed by HPLC was employed to determine BPA and DES in environmental samples. The developed method provided spiked recoveries of 80–105%, relative standard deviations of less than 7%, and LOD of BPA (20.0 ng/L) and DES (23.0 ng/L), respectively. The proposed method offered easy preparation of sorbents, rapid analysis, high enrichment yields, and reliable quantitative assay.     

Removal of Pb and Cd from aqueous media and fish liver using novel polyurethane foam functionalized with pyrazolone as a new metal ion collector

In the present paper, an off-line preconcentration procedure for the determination of cadmium and lead by flame atomic absorption spectrometry (FAAS) is proposed. Polyurethane foam (PUF) functionalized with o-aminophenol (o-AP) followed by Pyrazolone (Pyr) packed in a minicolumn was used as a sorbent material. The metals were retained on the modified PUF, from which it could be eluted and effectively preconcentrated. The detection limits were 0.072 and 0.016 μg L⁻¹ for Pb and Cd respectively. Enrichment factors were 250 and 319 for lead and cadmium respectively. The procedure has been applied successfully to metal determination in water samples, fish liver and reference material.