Optimization of extraction technology of total flavonoids from toots of chenopodium glaucum (L.)using response surface methology

采用响应面法优化微波提取藜根黄酮的条件.在单因素试验的基础上,选取乙醇体积分数、微波提取时间、液料比为影响因子,应用Box-Behnken中心组合进行3因素3水平的试验设计,以藜根黄酮得率为响应值,进行响应面分析.结果表明,微波提取藜根黄酮的最佳提取条件为:乙醇体积分数70％、液料比16:1、微波功率500W、微波时间6min.在此优化工艺下藜根黄酮的得率为0.80％,即8.0mg/g.     

正交设计与响应面优化玄参黄酮提取工艺研究

以玄参总黄酮提取率为考察指标,在单因素实验分析的基础上,采用正交设计和响应面法对比研究不同溶剂与溶剂体积分数、微波功率、提取时间及液固比等因素对玄参总黄酮提取的影响.2种实验优化方法所得玄参总黄酮的最佳提取工艺条件:固定微波功率值为500W;乙醇体积分数为60%或60.37%;提取时间为10或11.17min;液固比30∶1或31.39∶1m L/g,验证实验总黄酮提取率为1.107%~1.192%.2种优化方法所得结论基本一致,正交设计实验次数少,响应面法更精确,预测能力更强,适用范围更广.     

鸡血藤中黄酮类化合物提取工艺的研究

对提取鸡血藤中黄酮类物质的工艺条件进行优选。在单因素考察的基础上,选用4个实验因素(提取温度、提取时间、料液比、乙醇体积分数)进行3水平正交试验优选,确定提取鸡血藤中总黄酮的最佳工艺参数。4种因素对鸡血藤中总黄酮提取结果的影响程度由大到小的次序为提取时间、乙醇体积分数、提取温度、料液比。总黄酮最佳工艺条件:料液比1∶30、乙醇体积分数50%、提取温度80℃、提取时间3 h,在此工艺条件下,鸡血藤中总黄酮的提取率为7.75%。该提取工艺合理,总黄酮提取率高。     

川佛手中多酚类物质的微波和超声波联合提取工艺优化

采用微波和超声波提取技术,实现了川佛手中多酚类物质的有效提取.在微波功率800 W和微波提取时间40 min的条件下,通过单因素实验条件优化,考察了超声功率、乙醇浓度、提取温度、超声时间和提取料液比对提取效率的影响;通过正交试验设计,确定了最佳提取工艺条件参数,即超声功率800 W、乙醇体积分数60%、提取温度55℃、超声时间1.0 h和提取料液比1∶20 g/m L;通过验证实验,得到川佛手多酚的提取率约为20.79 mg/g.     

藜蒿中黄酮类化合物的微波辅助萃取研究

应用密闭微波萃取装置，分别对藜蒿茎和藜蒿叶中黄酮类化合物进行微波萃取研究。采用正交试验方法得到微波提取藜蒿中黄酮类化合物的最佳条件。微波提取藜蒿茎的最佳条件为乙醇体积分数70％，微波功率800W，提取温度80℃和料液比1：20；微波提取藜蒿叶的最佳条件为乙醇体积分数70％，微波功率600W，照射时间12min，提取温度70℃和料液比1：20；在最佳条件下，藜蒿茎和叶中总黄酮提取率分别为6．43％和7．01％。并将微波萃取与乙醇回流提取进行了比较。     

微波辅助法提取香根净油的研究

采用微波辅助法提取香根净油,通过实验确定了最佳提取工艺条件。研究结果表明,最佳提取工艺条件为：提取液中乙醇体积分数为80%,固液比1∶10（g/mL）,微波频率2450MHz,功率1190W,微波时间5min。最佳提取工艺条件下香根净油提取率为6.41%。     

响应面法优化菊花黄酮超声-微波辅助提取工艺及其抗氧化活性

以黄酮提取率为指标,采用单因素实验结合响应面法优化菊花黄酮的超声-微波辅助提取工艺,并研究了所提菊花黄酮的抗氧化活性.结果表明,菊花黄酮超声-微波辅助提取最佳工艺条件为:乙醇体积分数为76%,料液比为1∶52(g/mL),超声功率为200 W,超声时间为43min.在此工艺条件下,菊花黄酮提取率为10.623%.菊花黄酮对DPPH·和·OH清除能力明显强于BHT,表明菊花黄酮具有较强的抗氧化活性.     

翻白草中鞣质的微波提取工艺研究

采用微波辅助提取方法,以提取剂浓度、pH值、液固比、微波提取时间、温度等为考察因素,并以提取物中总鞣质的提取率为评价指标,使用磷钼钨酸-干酪素分光光度法为定量测定方法,在单因素实验的基础上,通过正交实验优化翻白草中鞣质的提取工艺.实验结果表明,最佳提取条件为:使用70%甲醇作为提取剂、液固比40∶1、提取液pH为8.0、提取温度为40℃、提取时间为10 min.还对翻白草不同部位(根、茎、叶)的鞣质含量进行分析,发现根部中鞣质的含量最大,其次为茎和叶.此外,采用高效液相色谱法对翻白草中鞣质的种类进行定性分析.     

葵花籽粕蛋白质、绿原酸分步提取工艺参数优化

在单因素试验的基础上,选取NaCl浓度、提取温度、料液比为自变量,以蛋白质提取率为响应值;选取乙醇体积分数、提取时间、料液比为自变量,以绿原酸的提取率为响应值,利用响应面法对葵花籽粕蛋白质、绿原酸的提取工艺进行优化,得到回归方程的预测模型。结果表明,最佳提取工艺条件为:蛋白质NaCl浓度1.51mol/L、液料比1∶12.88(g/mL)、提取温度60.27℃;绿原酸乙醇体积分数56.07%、液料比1∶16.03(g/mL)、提取时间47.06min.在此条件下,葵花籽粕蛋白质和绿原酸的提取率分别为36.64%和2.73%.     

超声波法提取紫甘薯叶总黄酮的工艺研究

采用超声波提取法,以总黄酮含量为考察指标,利用单因素试验法对影响总黄酮提取率的因素进行了分析,然后通过正交试验确定紫甘薯叶总黄酮的最佳工艺条件。研究表明,影响紫甘薯叶总黄酮提取率的主次因素为:溶剂pH值溶剂的浓度料液比提取时间。紫甘薯叶总黄酮的最佳提取工艺为:乙醇体积分数80%,料液比1∶40(W/V),提取时间30 min,提取溶剂pH 9。在此条件下甘薯叶中总黄酮提取率为8.22%。     

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.