胶束增稳荷移反应紫外分光光度法测定洛美沙星

提出了一种基于胶束增稳荷移反应测定洛美沙星的紫外分光光光度法 ,研究了在阳离子表面活性剂溴化十六烷基吡啶 (CPB)胶束体系中电子给体洛美沙星与电子受体四氯对苯醌之间的荷移反应产物的紫外光谱性质。发现CPB对洛美沙星与四氯对苯醌的荷移反应络合物有显著的增稳效应。洛美沙星的浓度在0 .8～ 5 4mg L范围内符合比尔定律 ,r =0 .9994。在测定波长 32 3nm处 ,络合物的表观摩尔吸光系数为 3.5 6×10 - 4L·mol- 1 ·cm- 1 。本方法用于片剂中洛美沙星含量的测定 ,其回收率为 97.8%～ 10 0 .5 % ,相对标准偏差为0 .9%～ 2 .4 %。     

奎宁与氯冉酸的胶束增敏荷移反应及其测定

提出了一种基于胶束增敏荷移反应测定奎宁的光度分析法。研究了在阳离子表面活性剂氯化十六烷基吡啶 (CPC)胶束体系中电子给体奎宁与电子受体氯冉酸之间的荷移反应产物的光谱性质。发现CPC对奎宁与氯冉酸的荷移反应络合物的光吸收有显著的增强作用 ,使络合物的表观摩尔吸光系数提高了 2 .5倍(λmax=5 2 0nm ,ε=3.6 4× 1 0 3 L·mol-1 ·cm-1 )。奎宁浓度在 2 0～ 80 0mg/L范围内符合比耳定律 ,r =0 9991。本方法用于片剂中奎宁含量的测定 ,其回收率为 97.3%～ 99.2 % ;5次测定的相对标准偏差为 1 .6 %～ 2 5 %。     

电荷转移络合物分光光度法测定磺胺脒的研究

研究了电子给体磺胺脒与电子受体对苯醌之间的荷移反应。结果表明 ,在乙醇介质中磺胺脒与对苯醌能形成橙红色电荷转移络合物 ,且反应体系的pH范围较宽。络合物的最大吸收波长λmax=497.6nm ,表观摩尔吸光系数为 2 .3 5× 1 0 3L·mol- 1 ·cm- 1 ,比耳定律的线性范围是 0～ 5 0mg/L ,络合比为 1∶2。应用拟定的方法测定磺胺脒制剂的含量 ,平均回收率为 1 0 0 .4% ,可用于磺胺脒制剂的分析。     

罗红霉素与紫色素的荷移反应及其测定

建立了一种测定罗红霉素的方便而快捷的荷移分光光度法。罗红霉素与紫色素在乙醇介质中发生电荷转移反应 ,荷移络合物在 5 4 4nm处有最大吸收 ;表观摩尔吸光系数是 6 .5 6× 10 3L·mol- 1 ·cm- 1 ,该络合物的组成是 1∶1,稳定常数是 3× 10 4 。药物浓度在 0～ 12 0mg L范围内服从比耳定律。当罗红霉素浓度为 5 0mg L时 ,5次测定结果的相对标准偏差为 1.3%。利用本法测定了罗红霉素胶囊中有效成分的含量 ,并与文献法进行比较 ,二者结果基本吻合 ,回收率在 96 %以上。     

司帕沙星与茜素红荷移反应的研究

采用紫外分光光度法研究了π电子受体茜素红与电子给予体司帕沙星的荷移反应。确定了反应条件,建立了一种快速简便灵敏准确测定司帕沙星的荷移分光光度法。结果表明,司帕沙星与茜素红在(4+6)乙醇-水介质中,室温条件下即可形成1∶1稳定的荷移络合物,该络合物的最大吸收波长为530 nm,表观摩尔吸光系数为4.8×103L.mol-1.cm-1,司帕沙星药物质量浓度在6~160mg/L范围内服从比尔定律,r=0.9991。当该法用于片剂中司帕沙星的测定时,回收率为99.75%~100.00%,相对标准偏差为1.4%(n=10)。     

诺氟沙星荷移络合物的荧光特性和应用

研究了电子受体四氯对苯醌(TCBQ)和2,3二氰5,6二氯1,4对苯醌(DDQ)与电子给体诺氟沙星之间的荷移反应。实验发现,诺氟沙星与以上两种电子受体可生成稳定的nπ络合物,其荧光强度较之诺氟沙星分别增强了12和17倍。据此建立了两种基于荷移反应简便可靠地测定诺氟沙星的荧光光谱新方法。TCBQ法和DDQ法测定诺氟沙星的浓度分别为0.02~1.2和0.14~2.8mg/L时,荧光强度与质量浓度呈良好的线性关系。该方法已成功地用于药物制剂中诺氟沙星含量的测定,其回收率(%)分别为98.87±142~99.63±1.26和98.49±1.46~99.21±1.62。本方法也可用于生物体液中诺氟沙星的测定。     

阿替洛尔与醌茜素的荷移反应研究

研究了阿替洛尔与醌茜素之间的荷移反应。阿替洛尔作为电子给体,醌茜素作为电子受体,两者在乙醇-水介质中反应生成荷移络合物。该络合物的λmax=568nm,表观摩尔吸光系数为7.91×103L.mol-1.cm-1,阿替洛尔药物质量浓度在0～30mg/L范围内服从比耳定律,相对标准偏差为0.92%(n=6)。应用本法测定了片剂中阿替洛尔的含量,回收率为98.9%～101.6%。     

阿奇霉素与茜素的电荷转移反应及其测定

建立了一种快速测定阿奇霉素的荷移分光光度法。阿奇霉素与茜素在乙醇介质中发生电荷转移反应 ,电荷转移络合物在 5 4 6nm处有最大吸收 ,表观摩尔吸光系数为 5 .79× 10 3 L·mol-1·cm-1;该络合物的组成是 1∶1;稳定常数为 4 .8× 10 3 ;药物浓度在 5～ 12 0mg/L范围内服从比耳定律。利用本法测定了阿奇霉素制剂中有效成分的含量 ,并与文献法进行比较 ,二者结果基本吻合。     

氧氟沙星与四氰基乙烯的荷移反应研究

研究了氧氟沙星与四氰基乙烯 (TCNE)的荷移反应 ,确立了形成电荷转移 (CT)络合物的最佳条件。在丙酮介质中 ,于 50℃水浴中恒温 30 min即可形成 1∶ 1络合物 ,其最大吸收波长为 40 9nm。表观摩尔吸光系数 ε为 2 .8× 1 0 4 L· mol- 1· cm- 1。在 0～ 1 2 μg· m L- 1范围内符合比耳定律。方法的相对标准偏差小于 1 %。对形成 CT络合物的机理进行了探讨。用拟定的方法对样品氧氟沙星药片进行测定 ,结果与紫外分光光度法一致 ,回收率符合要求     

荷移光度法测定双嘧达莫

用光度法研究了双嘧达莫与氯冉酸之间发生的电荷转移反应,其中双嘧达莫是电子给予体,氯冉酸是电子接受体,反应介质是乙醇丙酮混合溶剂。应用等摩尔连续变换法和摩尔比法测得荷移络合物的组成为1∶1,稳定常数为3.9×104。络合物在526nm波长处有最大吸收,双嘧达莫浓度在10～380mg·L-1范围内服从比耳定律,相关系数为0.9996,表观摩尔吸光系数为1.34×103L·mol-1·cm-1,回收率为98.4%,测定结果的相对标准偏差为1.14%。应用该法可以快速测定双嘧达莫片中有效成分的含量,结果满意。     

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.     

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.     

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.