流动注射化学发光抑制法测定吡罗昔康

基于吖啶橙在氢氧化钠介质中能被高锰酸钾氧化产生较强的化学发光,吡罗昔康能强烈抑制其化学发光,建立了高锰酸钾-吖啶橙-吡罗昔康化学发光抑制测定吡罗昔康的新方法。吡罗昔康在1.0×10-5~7.0×10-4g/mL范围内与化学发光强度呈良好线性关系,方法的检出限为4.5×10-6g/mL,对1.0×10-5g/mL吡罗昔康连续进行6次测定的相对标准偏差为3.6%。     

鲁米诺-铁氰化钾化学发光体系测定甲基多巴

本文研究发现,铁氰化钾在碱性条件能氧化鲁米诺产生微弱的化学发光,而甲基多巴能大大增强该体系的发光强度.基于此,结合流动注射技术,建立起一种直接测定甲基多巴的流动注射化学发光新方法.该方法的检出限为5.7×10-10g/mL,甲基多巴浓度在1.0×10-9～1.0×10-7g/mL范围内与发光强度呈良好的线性关系.对1.0×10-9g/mL的甲基多巴平行测定11次,其相对标准偏差为2.3%.利用该方法对甲基多巴片剂含量的测定,结果令人满意.     

高锰酸钾-亚硫酸钠-氨基比林化学发光体系的研究

采用流动注射技术,研究了高锰酸钾-亚硫酸钠-氨基比林体系的化学发光行为,对影响化学发光强度的诸因素进行了实验和探讨,建立了化学发光法测定氨基比林的新方法.方法的检出限为3×10-8 g/mL,线性范围为1.0 ×10-7～8.0×10-5 g/mL.对4.0×10-6 g/mL的氨基比林进行11次平行测定,得方法的相对标准偏差为1.7%.方法用于药剂中氨基比林含量的测定,结果与分光光度法测得值一致.     

流动注射后化学发光法测定异烟肼

本文发现了异烟肼在铁氰化钾-钙黄绿素化学发光反应体系中的后化学发光反应。优化了反应条件,建立了一种利用后化学发光反应测定异烟肼的流动注射化学发光分析法。方法的检出限为6×10-8g/mL, 相对标准偏差为1.8% (2.0×10-6 g/mL 异烟肼,n=11）,线性范围为2.0×10-7~1.0×10-5 g/mL。此法已用于异烟肼片剂中异烟肼含量的测定,结果与药典方法测定值一致。     

铁氰化钾-鲁米诺体系后化学发光行为的研究-流动注射后化学发光法测定可待因

发现了可待因在铁氰化钾鲁米诺化学发光反应体系中的后化学发光反应。优化了反应条件,建立了一种利用后化学发光反应测定可待因的流动注射化学发光新方法。方法的检出限为3×10-8g mL,相对标准偏差为1.9%(1.0×10-6g mL可待因,n=11),线性范围为8.0×10-8～1.0×10-5g mL。此法已用于可待因片剂中可待因的测定,结果与药典方法测定值一致。     

反向流动注射化学发光法测定五氟利多

基于五氟利多对 KIO4- Luminol体系化学发光有强烈的增敏作用, 结合反向流动注射技术, 首次建立了测定五氟利多的流动注射化学发光的方法; 在优化的实验条件下, 测定五氟利多的线性范围为 4.0× 10- 8～ 1.0× 10- 5 g/mL, 检出限为 9.2× 10- 9 g/mL, 对 4.0× 10- 7 g/mL的五氟利多进行 11次平行测定, 方法的相对标准偏差为 2.1%; 该法用于片剂五氟利多的含量测定, 结果满意.     

时间分辨后化学发光同时测定林可霉素和卡那霉素

根据林可霉素、卡那霉素在过氧化单硫酸盐(PMS)-鲁米诺(Luminol)体系中的化学发光反应动力学性质的明显差异,建立了时间分辨后化学发光同时测定林可霉素和卡那霉素的新方法.在PMS-鲁米诺体系中林可霉素化学发光反应较快,0.8s达到最大值,峰尖锐;卡那霉素化学发光反应较慢,54.8s后达到最大值,峰平缓,且其动力学曲线呈现出随时间分开的两个独立的发光峰,互不干扰.该方法测定林可霉素、卡那霉素的线性范围分别为4.0×10-9～8.0×10-7 g/mL、4.0×10-7～8.0×10-5 g/mL,对8.0×10-8 g/mL的林可霉素溶液和8.0×10-6 g/mL的卡那霉素溶液进行测定,其相对标准偏差(RSD,n=11)分别为4.6％和3.3％,测定林可霉素和卡那霉素的检出限分别为1.0×10-9 g/mL和1.0×10-7 g/mL.     

流动注射-抑制化学发光测定阿莫西林的方法研究

基于阿莫西林对Co2+催化的鲁米诺-H2O2化学发光体系的抑制作用,首次建立了阿莫西林的流动注射化学发光抑制分析法。发光信号的降低值ΔΙ与阿莫西林的质量浓度在8×10-9~4×10-5g/mL的范围内呈良好的线性关系,检出限为2.7×10-9g/mL,对1.0×10-5g/mL阿莫西林测定的相对标准偏差为1.89%(n=11)。本方法快捷、简便且具有很高的灵敏度,可用于阿莫西林胶囊中阿莫西林含量的测定,并与药典规定的方法进行对照,结果满意。     

高锰酸钾-甲醛-巯嘌呤化学发光体系的研究

在酸性条件下,甲醛与高锰酸钾能够产生较弱的化学发光,而巯嘌呤的存在能够大大地增强该化学发光强度。在一定浓度范围内,增加的发光强度与巯嘌呤的浓度呈良好的线性关系,由此建立了一种测定巯嘌呤的流动注射化学发光方法。方法的检出限为8.7×10-9 g/mL,线性范围为1.0×10-8~1.0×10-6 g/mL,相对标准偏差为3.1%(c=5.0×10-7 g/mL,n=11)。     

流动注射化学发光法测定安痛定注射液中的氨基比林

在甲醛存在下 ,高锰酸钾与氨基比林能够发生化学发光反应 ,产生很强的化学发光 ,据此采用流动注射技术建立了一种测定氨基比林的化学发光分析法。方法的检出限为 3 .0× 10 -8g/mL ,相对标准偏差为 1.3 % (4 .0× 10 -6g/mL氨基比林 ,n =11) ,线性范围为 1.0× 10 -7～ 8.0× 10 -5g/mL氨基比林。该法已用于安痛定注射液中氨基比林含量的测定。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.