A concise synthesis of glycosyl-α-amino acid derivatives via homologation of dialdoses into bromo uronic acids and esters

The synthesis of the compounds of the title involves three steps from dialdoses. The reaction between potassium dibromoacetonitrile carbanion and protected dialdoses provides corresponding β-bromo-α-ketonitriles that are easily transformed into α-bromo esters by treatment with methanol or isopropanol or α-bromo acids by treatment with t-BuOH. Substitution of the bromine by sodium azide onto these last compounds and subsequent catalytic hydrogenation of the azide group afford the targeted glycosyl-α-amino acid derivatives. This methodology represents the most rapid access to the key α-amino acid moiety of polyoxins.     

二安替比林邻溴苯基甲烷与锰显色反应研究

合成了新试剂二安替比林邻溴苯基甲烷（ＤＡＯＢＭ），研究了它和Ｍｎ（Ⅶ）的显色反应条件．在磷酸介质中，Ｍｎ（Ⅱ）存在下，ＤＡＯＢＭ和Ｍｎ（Ⅶ）生成橙色产物，λｍａｘ为４８０ｎｍ，ε为９．６６×１０５Ｌ·ｍｏｌ－１·ｃｍ－１，锰含量在０．１－１．２μｇ／２５ｍＬ内符合比尔定律．方法用于食品中痕量锰的测定，结果满意．     

Liquid‐Phase Synthesis of 2‐Methyl‐2‐Aryloxypropanoic Acid Derivatives from Polyethylene Glycol) Supported 2‐Bromo‐2‐Methylpropanoate

An efficient liquid‐phase synthesis of 2‐methyl‐2‐aryloxypropanoic acid derivatives with good yields and high purity on soluble polyethylene glycol (PEG) has been developed by treatment of PEG‐bound 2‐bromo‐2‐methylpropanoate with phenoxides in the presence of a catalytic amount of NBu₄I and KI, and subsequent cleavage from the PEG.     

Selective α-Bromination of β-Keto Esters in Reusable PEG-400 under Mild and Catalyst-free Conditions

An efficient bromination protocol for the synthesis of α-bromo-β-keto esters has been developed. In PEG-400 （poly（ethylene glycol-400））, a variety of β-keto esters were treated with NBS （N-bromosuccinimide） at room temperature to selectively afford the corresponding α-monobromination products in excellent yields. It is noteworthy that the reaction was conducted under mild, environmentally benign and catalyst-free conditions.     

5-Br-PADAP-NO_2~--SCN~-三元离子缔合物分光光度法测定微量NO_2~-的研究

研究了在硫酸介质中 5 Br PADAP与NO-2 和SCN- 形成三元离子缔合物的最佳条件 ,其表观摩尔吸光系数ε550 =2 .4× 1 0 4 L/(mol·cm) ,缔合物组成比为n( 5 Br PADAP)∶n(NO-2 )∶n(SCN- ) =1∶1∶1 .提供了测定微量NO-2 离子的新方法 ,应用于环境水体中微量NO-2 离子的测定 ,结果较为满意。     

Simultaneous determination of amphetamine derivatives in human urine after SPE extraction and HPLC-UV analysis

Amphetamine derivatives are a class of compounds increasingly abused as recreational drugs in various regions of the world. Although d-amphetamine (AMPH) and 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) are among the most commonly used, the abuse of other designer drugs such as 4-bromo-2,5-dimethoxyphenethylamine (2C-B) and 4-methylthioamphetamine (4-MTA) and their involvement in acute intoxications has been increasingly reported. There is evidence that abusers ingest these compounds either alone or in combination and the respective monitoring is important for both legal and health care purposes in hospital emergency. In the present study a simple and clean solid-phase extraction procedure from urine of AMPH and MDMA, and their major metabolites p-hydroxyamphetamine (OH-AMPH) and methylenedioxyamphetamine (MDA) and 2C-B and 4-MTA was developed. Analysis was performed by HPLC-UV and the precision of the technique was between 2.9 and 5.3% for all compounds. For the overall procedure, the precision values were between 3.3 and 5.9%. Recoveries obtained from spiked urines at three concentration levels were better than 84 +/- 4% for the six compounds. The limit of detection of the method for the compounds (between 5.3 and 84.0 ng) enables their identification in urine after ingestion of fatal and non-fatal doses. The main advantages of the present method lie in its simple, clean and reliable SPE extraction method of the six amphetamine derivatives from urine followed by their simultaneous detection and quantification by liquid chromatography with UV detection.     

New Synthesis of 2,2‐Bis(hydroxymethyl) methylenecyclopropane,a Key Intermediate for Antiviral Cyclopropavir

Synthesis of 2,2‐bis(hydroxymethyl)methylenecyclopropane (2) is described. Cyclopropane dicarboxylate 3 was reduced to diol 4, which was acetylated to give diacetate 5. Acetoxy‐bromo elimination afforded methylenecyclopropane 6. Debenzylation gave the title compound 2.     

Preconcentration/Separation of Some Metal Ions Using Sodium Dodecyl Sulfate Coated Alumina Modified with Bis(5‐bromo‐2‐hydroxy‐benzaldehyde)‐2‐methyl‐1,5‐pentane Diimine (BBHBPDI) Prior to Their Flame‐AAS Determination

Preconcentration/separation of Co(II), Fe(III), Pb(II), Cr(III), Cu(II) and Cd(II) ions using bis(5‐bromo‐2‐hydroxy‐benzaldehyde)‐2‐methyl‐1,5‐pentane diimine (BBHBPDI) on SDS coated alumina has been reported. The influences of the analytical parameters including pH, ligand and SDS amount, type and concentration of eluent and sample volume on metal ions recoveries were investigated. At optimum values of all variables the relative standard deviation are between 2.5–2.7 and preconcentration factor was 375, while recoveries for all understudy metal ions are higher than 95%, determination limits are between 1.5–2.7. The method has been successfully applied to determination of Co(II), Fe(III), Pb(II), Cr(III), Cu(II) and Cd(II) ions content in some real samples.