N-Cyanation of Primary and Secondary Amines with Cyanobenzio-doxolone (CBX) Reagent

An efficient electrophilic N-cyanation of amines with a stable and less-toxic cyanobenziodoxole reagent towards the synthesis of cyanamides is disclosed. This synthetically practicable strategy allows the construction of a wide variety of cyanamides under very mild and simple conditions with a broad functional group compatibility, and showcases a huge potential in late-stage modification of complex molecules.     

NBD-Cl as a Post-Column Reagent for Primary and Secondary Amines after Separation by Ion-Exchange Chromatography

In this study 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) is proposed as a post-column derivatization (PCD) reagent for the fluorescence detection of aliphatic primary and secondary amines after HPLC separation. Five primary (methylamine, isoamylamine, 2-phenylethylamine, putrescine, and histamine) and one secondary amine (dimethylamine) were separated isocratically on a cation-exchange column using HNO₃ (5 × 10^?3 mol L^?1) as the mobile phase. Post-column derivatization was based on two steps: 1) the derivatization of amines with NBD-Cl in alkaline medium, and 2) the acidification of the resulted mixture in order to minimize the background signal of the reagent and improve dramatically the sensitivity and determination range. The variables of the post-column reaction (concentration of NBD-Cl, buffer concentration and pH, reaction temperature, concentration of HCl, flow rates of the reagents) were thoroughly investigated. Critical chromatographic parameters such as the concentration of HNO₃, the percentage of organic solvent, and the column temperature were also examined to achieve adequate separation. An internal standard of 1,7-diaminoheptane was used. The developed post-column method provides the ability for a fully automated analysis, low detection limits (LODs 20–100 µg L^?1 with S/N = 3), and it requires less sample preparation. The applicability of the proposed analytical scheme was demonstrated by the determination of histamine (HIS) in tuna fish tissues according to US Food and Drug Administration (FDA) guidelines.     

Evaluation of Fluorescamine as a Phosphogenic Derivatizing Reagent of Primary Amines

Abstract

Fluorescamine has been shown to be a promising derivatizing reagent for the room temperature phosphorescence analysis of primary amino acids. The fluorescamine concentration used for derivatization in solution was 600 μg/ml and for direct derivatization, 1160 μg/ml. For derivatized primary amino acids the limits of detection were found to be between 0.8 ng and 2.9 ng with linear dynamic ranges between 2 and 3 orders of magnitude.     

Selective Removal of the Tert-Butoxycarbonyl Group from Secondary Amines: ZnBr2 as the Deprotecting Reagent

ZnBr₂ in dichloromethane is a convenient reagent for mild and selective removal of the tert-butoxycarbonyl group from secondary amines.     

A Precautionary Note Regarding Derivatization of Secondary Amines with Dialkylacetals of Formamide Other Than the Diethyl Derivative

Abstract

We have extended our earlier work on alkylation of secondary amino compounds with dimethylformamide diethyl acetal to other alkyl acetals, such as dimethyl and dipropyl acetal. All the alkylating DMT-dialkyl acetal reagents tested gave only N-ethyl derivatives of the secondary amines. The reagent purity was tested by preparing the esters of carboxylic acids, where the appropriate alkyl (methyl or propyl) ester is obtained. It is concluded that all dimethylformamide dialkyl acetals yield a single N-ethyl derivative of secondary amine. The reaction mechanism is not understood.     

A Precautionary Note Regarding Derivatization of Secondary Amines with Dialkylacetals of Formamide Other Than the Diethyl Derivative

Abstract

In an earlier communication we reported GC-MS studies on the reaction products of secondary amino tricyclics and dimethylformamide.¹ The diethyl acetal reaction products were identified as N-ethyl derivatives on the basis of mass spectroscopic analysis. In a follow-up study, we reported the same reaction products were formed from other DMF -dialkyl acetals, such as dimethyl and dipropyl acetals.² In view of this unusual reaction we reinvestigated the structure of the reaction products utilizing alternative spectroscopic methods, viz. NMR and IR.     

Preliminary Evalution of Fluorscamine As a Clorimetric Reagent for Primary Amines

Abstract

Fluorescamine reacts efficiently with primary amines to form pyrrolinones with long wavelength absorption at 390–410nm. A procedure has been worked out which allows the use of this reaction for the colorimetric assay of primary amines.     

2-(2-Thiazolylazo)-p-cresol(TAC) as a Reagent for the Spectrophotometric Determination of Lead(II)

Abstract

The reaction between lead(II) and 2-(2-Thiazolylazo)-p-Cresol(TAC) in the presence of TERGITOL NPX (4 mg/ml) at an apparent pH 9.0–10.0 results in an intensely colored complex which is stable for at least 4 hr.

The composition of the complex is 1:2 cation: TAC and the log of the formation constant is 11.92 ± 0. 40. Beer's law is obeyed up to 6.0μg.ml^?1 of lead(II) at 650nm.

The apparent molar absorptivity at 650 nm is 2.07 × 10⁴ 1. mole^?1.cm^?1 and the detection limit was obtained as 10.0 ng.ml^?1 of lead(II).

The method is applied to determination of lead(II) in copper-base alloy.     

Nucleophilic Vinylic Substitutions of (E)- and (Z)-Ethyl 3-Aryl-3-chloro-2-cyanopropenoates with Primary and Secondary Amines

Some new (Z)-ethyl 3-amino-3-aryl-2-cyanopropenoates have been prepared in good yields by reacting (E)- and (Z)-ethyl 3-aryl-3-chloro-2-cyanopropenoates with primary and secondary amines. The (Z)-isomers were exclusively formed.although the starting material consisted of a mixture of (E)- and (Z)-isomers (≈ 1:1)     

The Use of Chloroformamidine Hydrochloride as a Reagent for the Synthesis of Guanidines from Electron Deficient Aromatic Amines

In efforts to optimize a manufacturing process for an internal development compound, a clean, efficient approach to guanidine synthesis using chloroformamidine hydrochloride was identified. To investigate the general utility of this methodology towards electron‐deficient aromatic amines, a set of favorable conditions were developed from a series of screens, and the scope of the reaction was probed. The successful application of this chemistry to a variety of pyridines, anilines, and heterocyclic compounds highlights its use as an improved, alternative guanylation method for this often challenging set of aromatic amines.     

Electrogenerated Base-Promoted Synthesis of Dithiocarbamate Acid Esters and 3-(N-Substituted-amino)-2-cyanodithiocrotonates from Primary or Secondary Amines and Carbon Disulfide

Electrogenerated cyanomethyl anion promotes the reaction between primary or secondary amines, carbon disulfide, and alkyl or benzyl halide. Secondary amines are converted to alkyl or benzyl dithiocarbamates, whereas primary amines give N-substituted alkyl or benzyl 3-amino-2-cyanodithiocrotonates. The mechanisms are discussed.     

PAN-S作为显色剂的研究

目前,一些性能优良的光度显色剂水溶性较差,一般需用有毒性的有机溶剂进行萃取光度测定。因此,改造老试剂,寻求可溶性的无毒新试剂对分析化学是有意义的。Ohshita等人^[1]通过2-氨基吡啶重氮化与β-萘酚磺酸偶联合成了1-(2-吡啶偶氮)-2-萘酚-磺酸(简称PAN-S),合成步骤繁琐,提纯困难,产率低。张孙玮等曾用PAN直接磺化来制备PAN-S,但由于磺化后用氢氧化钠处理,未能得到纯品。我们发现,将磺化后的溶液倾入适量的水中,就能析出PAN-S。该法具有制备简单、易得纯品、成本低等特点。本文报导PAN-S的制备和性质及其与金属离子的反应。     

Synthesis and Bioassay of Ethyl-2- (2-((Diethoxyphosphoryl) (Aryl) Methylamino)Thiazol-4-Yl)-2-(Methoxyimino)Acetates

Abstract

A simple, efficient, and environmentally benign methodology has been accomplished for the synthesis of α-aminophosphonates by one-pot three-component reaction of ethyl-2-amino-α-(methoxy-imino)-4-thiazoleacetate, aldehydes, and diethylphosphite by using Amberlyst-15 as catalyst at room temperature under solvent-free conditions. Their chemical structures were characterized by infrared (IR), NMR (¹H, ¹³C & ³¹P), mass spectral, and elemental analysis. All the title compounds were screened for radical-scavenging activity by 1,1-diphenyl-2-picrylhydrazyl (DPPH), nitic oxide (NO), and hydrogen peroxide (H₂O₂) methods.

Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: Additional text and figures.     

查尔酮衍生物E-2-(甲氨基)-7-(3-(吡啶基)丙烯酰基)卓酮的合成(英文)

以2-乙酰基-7-(甲氨基)卓酮(1)为原料,经由与各种吡啶醛的Claisen-Schmidt缩合反应得到查尔酮衍生物E-2-(甲氨基)-7-(3-(吡啶基)丙烯酰基)卓酮(2～5).全部合成产物均为新化合物,未见文献报道;其结构均由红外光谱分析、1H核磁共振、质谱及元素分析得以证实.     

Synthesis of N-(2-(Methylamino)ethyl) Derivatives of 2H-Phthalazin-1-ones

A series of new alkyl, tosyl, acetyl, and tert-butoxycarbonyl derivatives of 2-(2-aminoethyl)-phthalazinones were efficiently synthesized by reaction of lactams with N-Boc-, N-acetyl-, or N,O-ditosyl derivatives of N-methylethanolamine in the presence of MeONa or under Mitsunobu reaction conditions. Selected compounds were converted into corresponding 2-[2-(methylamino)ethyl]phthalazinones in good yields.     

Reaction of 2-(4-Arylthiazol-2-yl)-4-chloro-3-oxobutyronitriles with Secondary Aliphatic Amines

We have obtained 2-(4-arylthiazol-2-yl)-4-chloro-3-oxobutyronitriles by acylation of 4-aryl-2-cyanomethylthiazoles with -chloroacetyl chloride. We have studied their reaction with secondary aliphatic amines, leading to formation of 4-dialkylamino-2-(4-arylthiazol-2-yl)-3-oxobutyronitriles, and also intramolecular alkylation with formation of 3-aryl-7-cyano-6(5H)-oxopyrrolo[2,1-b]thiazoles. We have determined some aspects of the tautomerism of the synthesized compounds.     

On-Line Derivatization of N-acetylcysteine Using Ethyl-Propiolate as a Novel Advantageous Reagent and Sequential Injection Analysis

This study reports a novel automated assay for the determination of N-acetylcysteine (NAC). The method is based upon the on-line derivatization of the analyte with a new reagent, ethyl-propiolate (EPL), to form a UV-absorbing derivative. The reaction is fast, proceeds in aqueous solutions under mild conditions and is, therefore, ideal for automation using sequential injection analysis. All major chemical and instrumental variables were examined thoroughly. The assay was validated for linearity, range, LOD-LOQ, within and day-to-day precision, selectivity, and accuracy. The experiments confirmed its suitability for the reliable quality control of NAC-containing formulations at a sampling rate of 80 h^?1.     

氮杂环荧光试剂2-(11H-苯[a]咔唑)乙基氯甲酸酯对胺类化合物标记及质谱鉴定

含氮类荧光试剂2-(11H-苯[a]咔唑)乙基氯甲酸酯(BCEC-Cl)经柱前衍生处理后,采用荧光检测及柱后在线质谱鉴定对食品中胺类化合物进行了测定。标记反应在pH9的硼酸缓冲液中进行,3min后获得稳定的荧光产物。衍生物于λex=279nm激发条件下产生强烈荧光,其发射波长在λem=380nm处。产物的分离在EclipseXDB-C8色谱柱(150mm×4.6mm,5μm)上进行,采用梯度洗脱对12种脂肪胺衍生物进行了优化分离。采用大气压化学电离源(APCISource)正离子模式进行在线的柱后质谱鉴定,实现了多种脂肪胺衍生物的快速、准确测定。建立的方法具有良好的重现性,回归系数大于0.9996,检出限为1.8~14fmol。     

N-Isocyaniminotriphenylphosphorane (Ph3PNNC) as an Efficient Reagent for the Synthesis of Fully Substituted 1,3,4-Oxadiazoles from 3-Phenyl-2-Propynoic Acid,Secondary Amines and Aromatic Bis-Aldehydes

Abstract

Reactions of N-isocyaniminotriphenylphosphorane (Ph₃PNNC) with aromatic bis-aldehydes (isophthalaldehyde and terphthalaldehyde) in the presence of 3-phenyl-2-propynoic acid and secondary amines proceed smoothly at room temperature and in neutral conditions to afford sterically congested 1,3,4-oxadiazole derivatives in high yields. The reaction proceeds smoothly and cleanly under mild conditions and no side reactions were observed.     

氯化亚铁催化的醛与伯胺和仲胺的氧化酰胺化反应

酰胺化反应是合成含有酰胺键的天然产物、材料以及药物分子中一类非常重要的化学反应.发展高原子经济性和环境友好的新型酰胺键的合成方法仍然是该领域具有重要研究意义和价值的研究内容.报道了在氯化亚铁作为催化剂和叔丁基过氧化氢作为氧化剂的条件下,实现了芳香醛和脂肪醛分别与伯胺和仲胺的直接酰胺化反应,获得了较高的收率.进一步研究发现,该反应体系对氮杂环化合物也有较好的适用性.