Oxidative decarboxylative synthesis of 2-H-imidazolines from glyoxylic acid and 1,2-diamines

A novel method to prepare 2-H-imidazolines from glyoxylic acid monohydrate and 1,2-diamines is described; the key reaction of this method is the oxidative decarboxylation of the 2-carboxy imidazolidines by NBS.     

New solid support for the synthesis of 3'-oligonucleotide conjugates through glyoxylic oxime bond formation

A novel solid support 1 was synthesized to incorporate glyoxylic aldehyde functionality at the oligonucleotide 3'-terminus. 6-mer and 11-mer oligonucleotide sequences containing 3'-glyoxylic aldehyde functionality were prepared by using this support. These modified oligonucleotides were coupled to reporters containing an aminooxy group to prepare oligonucleotide 3'-conjugates through glyoxylic oxime bond formation. The hydrolytic stability of a glyoxylic oxime linkage was also investigated. [reaction: see text].     

Novel intermolecular carbon radical addition to a nitrone: asymmetric synthesis of alpha-amino acids

A nitrone was used as a synthetically useful radical acceptor in carbon-carbon bond-forming radical reactions; the intermolecular addition of alkyl radicals to chiral glyoxylic nitrone was studied; a high degree of stereocontrol in radical addition to glyoxylic nitrone was achieved to provide a new method for asymmetric synthesis of alpha-amino acids.     

Modular synthesis of supramolecular ureidopyrimidinone-peptide conjugates using an oxime ligation strategy

A convenient method to prepare supramolecular bioconjugates in a facile and scalable manner is by a modular approach, whereby self-assembling units and peptides are coupled using oxime chemistry. We here report syntheses of bioactive ureidopyrimidinone-based peptide conjugates, and their resultant self-assembly into fibrous structures.     

A straightforward synthesis of 5'-peptide oligonucleotide conjugates using N(alpha)-Fmoc-protected amino acids

[reaction: see text] 5'-Peptide oligonucleotide conjugates were prepared stepwise on a single support using N(alpha)-Fmoc-protected amino acids and unprotected phosphate groups. The method uses commercially available reagents and is successful with most natural amino acids. The simplicity of the method may encourage researchers to prepare new oligonucleotide-peptide conjugates with novel properties.     

Synthesis of DNA-peptide conjugates by solid-phase fragment condensation

[reaction: see text] DNA-peptide conjugates were synthesized by condensing partially protected peptide fragments and oligonucleotides on a CPG support using diisocyanatoalkane as a linker. After cleavage and deprotection with aqueous ammonia, pure products were obtained by single RPHPLC purification in satisfactory yields and identified by a MALDI-TOF MS spectrometer. This method allows one to prepare DNA-peptide conjugates with any components and sequences of DNA and peptides.     

Determination of glyoxylic acid in urine by liquid chromatography with fluorescence detection, using a novel derivatization procedure based on the Petasis reaction

The Petasis reaction is the multi-component reaction of a carbonyl compound, amine, and arylboronic acid to form an α-amino acid or a β-aminoalcohol. In this work, as the first analytical application of the Petasis reaction, a high-performance liquid chromatographic (HPLC) method with fluorescence detection was developed for determination of glyoxylic acid. The glyoxylic acid was derivatized with 1-pyreneboronic acid, as fluorescent arylboronic acid, in the presence of N-methylbutylamine, as amine, to give a fluorescent α-amino acid. HPLC separation of the fluorescent derivative was performed within 30 min on an octyl column eluted with a gradient prepared from acetonitrile and 50 mmol L(-1) acetate buffer (pH 4.0). The detection limit (S/N=3) for glyoxylic acid was 5.0 nmol L(-1) (20 fmol/injection). The method can be used to determine the concentration of glyoxylic acid in human urine without interference from biological components.     

A Convenient,Large-Scale Preparation of a Differentially Protected α-Aminoglycine Suitable for the Synthesis of α-Aminoglycine-Containing Peptides

α-Boc-amino-Fmoc-glycine 6 was prepared in two steps from 9-fluorenyl-methylcarbamate 1, glyoxylic acid 3 and t-butyl carbamate 5. This compound is useful in Solid Phase Peptide Synthesis to prepare α-aminoglycine-containing peptides using Fmoc-strategy.     

草酸电解合成乙醛酸连续化工艺研究

针对传统草酸电解生产乙醛酸工艺只能间歇循环的缺陷,本文提出模拟连续化实验方案,并分别设计阴极冷却反应器和阴极冷却固定床反应器,探讨连续化实验的可行性.另外还考察了草酸饱和度和温度工艺参数对反应的影响.实验表明,保持草酸过饱和和利用变温操作可在反应停留时间(30m in)内于连续化反应过程中得到分别含有3.76%和3.66%乙醛酸的反应液,因此阴极冷却固定床反应器可望实现草酸电解还原乙醛酸的连续化生产.     

多波长线性回归-矩阵法同时测定乙二醛、乙醛酸、草酸的含量

根据实验得出的乙二醛、乙醛酸、草酸三组分混合物中各组分在特定波长下呈现出的良好的线性关系,建立起三组分质量浓度与混合吸光度的回归方程组,形成了多波长线性回归-矩阵法,实现了乙二醛氧化制备乙醛酸体系中反应产物乙二醛、乙醛酸、草酸含量的同时测定.研究结果表明:当乙二醛检测下限为1.024 mg/L时,回收率为94%~98%...     

Surface functionalized silver nanoparticle conjugates: demonstration of uptake and release of a phototherapeutic porphyrin dye

A facile supramolecular approach to prepare surface functionalized silver nanoparticle conjugates has been established and their enhanced molecular recognition features have been explored to demonstrate the uptake and stimulus responsive release of a phototherapeutic porphyrin dye, the TMPyP.     

阴极冷却固定床电合成乙醛酸的连续过程模拟

联用反应动力学、电荷衡算和物料衡算建立阴极冷却固定床草酸电合成乙醛酸反应器模型方程.针对反应器连续化操作过程,用正交配置法数值求解该模型方程.结果表明,在连续化操作的反应初期,反应液中的乙醛酸能够较快地达到预定浓度,但继续增加反应器的长度,反应的效果不明显.该模型还模拟了分段温控和部分回流对反应的影响.结果表明,分段温控和部分回流均可较好地提高乙醛酸在阴极液中的浓度.计算结果与试验操作基本相符.该结果对阴极冷却固定床草酸电合成乙醛酸的连续化操作工艺和反应器的优化具有重要的参考意义.     

A new method of ion chromatography technology for speedy determination and analysis in organic electrosynthesis of glyoxylic acid

Based on ion chromatography (IC) technology, we have developed a new method that combines ion chromatography with a conductivity detector to separate and determine the substances of glyoxal, glycolic acid, oxalic acid and glyoxylic acid. The ion chromatography was applied for the first time in quantitative determination of substances involved in electrosynthesis of glyoxylic acid. The method has been applied to separate and analyze simultaneously either glyoxylic acid and glyoxal in electroxidation of glyoxal, or glyoxylic acid and oxalic acid in electroreduction of oxalic acid. An aqueous Na2CO3-NaHCO3 or NaOH-Na2CO3 solution was confirmed to be the most desirable eluent. The experimental results demonstrated that the detection sensitivity is ahead of ppm grade, and the variation coefficients such as the retention time, the peak height and the peak area outperform 2%. All the recoveries of the detected substances are ranged between 97 and 103%. The method exhibits advantages of high selectivity, high sensitivity, speediness and simple apparatus requirement. Furthermore, simultaneous determination of a mixture of several substances can be achieved by the developed method, and even a neutral molecule of glyoxal can be also determined by choosing an appropriate composition and concentration of eluent.     

A Flexible Method for Covalent Double Functionalization of Graphene Oxide

A method for the double functionalization of graphene oxide (GO) under mild alkaline conditions has been developed. Two functional groups were covalently linked to GO in two steps: the first group was attached by an epoxide ring‐opening reaction and the second, bearing an amine function, was covalently conjugated to benzoquinone attached to the GO. The doubly functionalized GO was characterized by several techniques, confirming the sequential covalent modification of the GO surface with two different functional groups. This method is straightforward and the reaction conditions are mild, allowing preservation of the structure and properties of GO. This strategy could be exploited to prepare multifunctional GO conjugates with potential applications in many fields ranging from materials science to biomedicine.     

Facile polyol synthesis of ultrasmall water-soluble cobalt ferrite nanoparticles

A facile protocol to prepare ultrasmall citrate-coated cobalt ferrite NPs was proposed from the comparison between one-step and two-step chemical routes based on the polyol method. Infrared spectroscopy, thermogravimetry and zeta potential data indicated different coordinations of citrate groups affecting the NP colloidal stability. The magnetic core size and saturation magnetization were also affected. The surface-modified NPs prepared by the one-step route presented superior colloidal stability, low core (2.9 nm) and hydrodynamic (4.8 nm) sizes, high magnetization (45 emu/g), and can be considered suitable platforms to produce nanoparticle-biomolecule conjugates.     

Synthesis of DNA conjugates by solid-phase fragment condensation via aldehyde-nucleophile coupling

Oligodeoxyribonucleotides were synthesized that contain a novel nucleoside, 2′-O-(2,3-dihydroxypropyl)cytidine. Its 2′-diol group was blocked by an allyloxycarbonyl protecting group. Selective deprotection of diol group(s) of the support-immobilized blocked oligodeoxyribonucleotide by Pd(0) followed by periodate oxidation resulted in generation of the 2′-aldehyde group(s) on solid-phase. The modified oligonucleotides were used to prepare a number of conjugates with acridine, biotin and N-modified laminin peptides by oxime, hydrazone and hydrazine formation. The method may be applicable to the synthesis of oligonucleotide-peptide conjugates.     

Efficient bioactive oligonucleotide-protein conjugation for cell-targeted cancer therapy

Oligonucleotide-protein conjugates have important applications in biomedicine. Simple and efficient methods are described for the preparation of these conjugates. Specifically, we describe a new method in which a bifunctional linker is attached to thiol-oligonucleotide to generate a reactive intermediate that is used to link to the protein. Having similar conjugation efficacy compared with the classical method in which the bifunctional linker is attached first to the protein, this new approach produces significantly more active conjugates with higher batch to batch reproducibility. In a second approach, direct conjugation is proposed using oligonucleotides carrying carboxyl groups. These methodologies have been applied to prepare nanoconjugates of an engineered nanoparticle protein carrying a T22 peptide with affinity for the CXCR4 chemokine receptor and oligomers of the antiproliferative nucleotide 2’-deoxy-5-fluorouridine in a very efficient way. The protocols have potential uses for the functionalization of proteins, amino-containing polymers or amino-lipids in order to produce complex therapeutic nucleic acid delivery systems.     

Polyamide resin: A novel immunoadsorbent

A solid phase assay for radiolabeled antibody synthesizedde novo in vitro has been described (1). The solid phase consists of antigen covalently bound to bromacetyl cellulose, a useful but difficult to prepare immunoadsorbent. Herein, we describe the preparation of polyamide resin immunoadsorbent and the procedure for coupling antigen to the polymer. Data are presented that show that polyamide resin-Ag? conjugates can replace bromacetyl cellulose-Ag conjugates. The usefulness of this easily prepared and inexpensive immunoadsorbent is discussed.     

Synthesis of Aldehydes by Organocatalytic Formylation Reactions of Boronic Acids with Glyoxylic Acid

Reported herein is a conceptually novel organocatalytic strategy for the formylation of boronic acids. New reactivity is engineered into the α‐amino‐acid‐forming Petasis reaction occurring between aryl boronic acids, amines, and glyoxylic acids to prepare aldehydes. The operational simplicity of the process and its ability to generate structurally diverse and valued aryl, heteroaryl, and α,β‐unsaturated aldehydes containing a wide array of functional groups, demonstrates the practical utility of the new synthetic strategy.     

Analysis of Terbutaline in Human Serum by Thin-Layer Fluorimetry

Abstract

An assay procedure has been developed for the measurement of terbutaline levels in human serum following a single 5 mg oral dose. Intact drug could be analyzed, or conjugates hydrolyzed for the determination of total terbutaline. Terbutaline and metaproterenol (internal standard) were isolated from serum by ion-exchange fractionation followed by extraction into s.-butanol. The compounds were separated by thin-layer chromatography and fluorescence induced by heating with glyoxylic acid. Quantitation was performed in situ using a scanning densitometer. Serum levels of total terbutaline were followed in nine normal males, and intact terbutaline in three of these subjects.