α-氟-β-氨基酸酯的合成

采用简易方法从取代苯乙酮出发制得α-氟-β-脱氢氨基酸酯;在N,N-二甲基甲酰胺存在下用三氯硅烷将其还原,高收率和非对映选择性地合成了α-氟-β-氨基酸酯,其结构经1H NMR,13C NMR和MS确证。     

EUROPIUM(III) PICRATE COMPLEXES WITH α-(DIETHOXYPHOSPHORYL)-PROPANONE AND DIETHYL-1-METHYLVINYLPHOSPHATE: SYNTHESES,SPECTROSCOPY AND STRUCTURES

Abstract

The Eu(III) picrate complexes with the isomers α-(diethoxyphosphoryl)propanone and diethyl-1-methylvinylphosphate were synthesized and characterized by elemental analyses, IR spectroscopy and emission spectroscopy. X-ray single crystal analyses show that in both complexes the picrate anions are bidentate, bonded through the phenolic and one o-nitrogroup oxygens. The neutral ligands are bonded only through their phosphoryl oxygens, resulting in tricapped trigonal prism coordination polyhedra with C_3v symmetry.     

Reductive Isopropylation of Amino Groups in Lysine Containing Peptides

Abstract

Model peptides, Gly-Gly-Lys-Arg, Arg-Lys-Asp-Val-Tyr, and Pro-Gly-Lys-Ala-Arg were reductively alkylated with [²H₆]acetone and sodium borohydride to assess the effects on peptide behavior. Lysine residues were converted to ?-N-isopropyllysine which eluted between phenylalanine and histidine on amino acid analysis. Amino terminal groups were also modified to an extent which depended on the particular peptide (glycine 100%, arginine 30%, and proline 10%-20%). High voltage paper electrophoresis of native and isopropylated peptides showed similar properties except for minor decreases in the mobility of the modified peptides due mainly to increased molecular weight. Isopropyllysine was not an effective substrate for trypsin, and α-N-isopropyl-amino acids did not form dansyl chloride derivatives. These findings should aid in the location, by peptide mapping techniques, of specific modified residues in reductively isopropylated proteins.     

Determination of α-tocopherol in Cosmetic Products by Chronopotentiometry

Abstract

In the present study, a rapid chronopotentiometric method was developed for the determination of α-tocopherol in various cosmetic products. Determination of α-tocopherol is based on its irreverse oxidation by constant current at the planar glassy carbon electrode. The influence of the most important experimental parameters of chronopotentiometry was investigated. After optimization, an appropriate procedure for the sample preparation was developed. Under the defined experimental conditions, a detection limit of 7.5 mg L^?1 of α-tocopherol was obtained. The accuracy of the defined method was confirmed by means of recovery assay. The developed method was successfully applied to quantitation of α-tocopherol in various cosmetic products.     

微波促进立体选择性高效合成糖基α,β-不饱和酯类化合物

利用微波促进糖醛与叶立德(Ph3P=CHCOOEt)发生Wittig反应,立体选择性地合成了含有α,β-不饱和酯的糖烯类化合物,反应效率显著提高,使用不同的反应溶剂可实现对反应立体选择性的控制.并通过1H NMR中双键氢的偶合常数确定了产物的构型.     

无溶剂无催化剂条件下二硫代氨基甲酸酯衍生物的合成研究

主要研究了二硫代氨基甲酸酯衍生物的合成,将脂肪胺、CS2与α,β-不饱和羰基化合物或卤代烃在无溶剂无催化剂室温条件下,"一锅法"进行了Michael-type的加成反应,合成了二硫代氨基甲酸酯衍生物.该方法产率高,操作简单,是一种原子经济的合成方法,并可大规模地用于制药及农药方面.     

Efficient solid-phase synthesis of cyclic RGD peptides under controlled microwave heating

Cyclic RGD peptides are potent antagonists for the α_vβ₃ integrin receptor. In this Letter, microwave-assisted solid-phase synthesis of cyclic RGD peptides is described. In a coupling reaction between Fmoc-Arg(Pbf)-OH and high-loading H-Gly-Trt(2-Cl) resin, multiple coupling reactions were required for completion under the conventional HBTU activation. We found that the use of COMU, a new coupling reagent, under microwave heating to 50 °C accelerated the reaction even inside the resin. This method was applicable to the synthesis of linear pentapeptides, H-Asp(OtBu)-Xxx-Yyy-Arg(Pbf)-Gly-OH (Xxx = d-Phe(p-Br) or d-Tyr, Yyy = Lys(Boc) or MeVal). Cyclization of these peptides followed by deprotection gave the desired cyclic RGD peptides with high purity.     

An efficient method for the preparation of mono α-aryl derivatives of diethyl malonate and ethyl cyanoacetate using ethyl-1-imidazole carbamate (EImC)

An efficient method for the synthesis of mono α-aryl derivatives of diethyl malonate and ethyl cyanoacetate using ethyl-1-imidazole carbamate (EImC) has been described. Using this method many sterically hindered and highly substituted mono α-aryl derivatives of diethyl malonate and ethyl cyanoacetate were synthesized in high yield.     

Microwave-assisted novel and efficient one-pot synthesis of fused steroidal and non-steroidal isothiazoles

An efficient microwave promoted one-pot synthesis of steroidal and non-steroidal isothiazole derivatives from corresponding β-bromo-α,β-unsaturated aldehydes has been described using a sodium thiocyanate-urea system. The β-bromo-α,β-unsaturated aldehydes derivatives are efficiently synthesized from corresponding cyclic ketones using Vilsmeir formylation reaction. The synthetic protocol is also applied for the synthesis of antifungal brassilexin.     

Functional Magnetic Nanoparticles for Clinical Application: Electrochemical Immunoassay of Hepatitis B Surface Antigen and α-Fetoprotein

This work reports an efficient method to quantify the Hepatitis B surface antigen and α-fetoprotein in human serum using a functional magnetic nanoparticle-assisted sandwich-type electrochemical immunoassay. The Fe ₃ O ₄ magnetic nanoparticles were first modified with carboxyl functional groups to permit stable bioconjugation to the amine groups of most biological targets. The primary antibodies were then covalently stained on the surface of the functional magnetic nanoparticles, followed by the analyte and secondary antibodies, resulting in a sandwich-type (antibody-antigen-antibody/enzyme) immune complex. The secondary antibodies were labeled with horseradish peroxidase for the catalytic oxidation of 2-aminophenol to yield electrochemically reducible molecules. The separation using an external magnetic field guaranteed fast and reliable purification and enrichment of analytes. Quantitative analysis was performed upon representative clinical targets: Hepatitis B surface antigen and α-fetoprotein in human serum. The detection limits were 0.06 ng/mL for the former and 0.5 ng/mL for the latter, which were about 10 times lower than values obtained by conventional enzyme-linked immunosorbent assays. The reported method may be adopted as a general strategy for the sensitive and selective determination of additional proteins and biological molecules.