固相微萃取结合气-质联用分析侧柏叶中的挥发性成分

以产自河北的侧柏叶为原料,采用四种固相微萃取纤维对其中的挥发性成分进行提取,用气质联用进行分析,共分离出112种成分,采用质谱与保留指数进行定性,鉴定出87种成分(四种萃取纤维的提取物中都鉴定出的成分有59种),其中烯烃类51种(以单萜和倍半萜为主),烷烃类4种,芳香烃类3种,醇类18种,醛酮类3种,酯类4种,醚类3种,吡嗪类1种;另外采用质谱初步定性出12种。采用面积归一化法确定了它们的相对含量,含量较高的有(1R)-(+)-α-蒎烯、(+)-3-蒈烯、D-柠檬烯、β-水芹烯、δ-松油烯、β-榄香烯、石竹烯、顺式-罗汉柏烯、葎草烯、大根香叶烯D、δ-杜松烯、柏木脑等。对比所得结果可以发现,CAR/PDMS(85μm)的萃取纤维对侧柏叶中挥发性成分的提取效果较好。     

气相色谱/质谱法分析柏树叶挥发油的化学成分

采用水蒸气蒸馏技术提取了3种柏树叶的挥发油,经气相色谱/质谱分析,共分离和鉴定了64种化学成分,其主要成分为萜烯类,其他成分为烷烃类、醇类、酚类和酯类等。其中圆柏树叶中分离鉴定出33种挥发性成分,主要萜类为桧烯(20.99%)和柠檬烯(19.78%);中山柏树叶中分离鉴定出37种挥发性成分,主要为α-蒎烯(10.39%)、桧烯(11.19%)和δ-3-蒈烯(8.88%);龙柏树叶中分离鉴定出37种挥发性成分,主要为柠檬烯(24.56%)和β-月桂烯(8.04%)。分离鉴定出3种柏树叶的共有成分14种。     

火炬松挥发物的固相微萃取-气相色谱/质谱法分析

采用固相微萃取(SPME)技术,结合气相色谱/质谱(GC-MS)分析了火炬松枝条和针叶中的挥发性化合物,共鉴定了30种化学成分。其中枝条中分离鉴定出21种挥发性成分。主要成分为α-蒎烯、β-蒎烯、β-月蒎烯、反式-石竹烯、β-杜松烯、大根叶烯-D;针叶中分离鉴定出24种挥发性成分,主要成分为α-蒎烯、β-蒎烯、β-月桂烯、β-水芹烯、异长叶烯、反式-石竹烯、α-律草烯、大根叶烯-D、双环吉马烯和双环榄香烯。     

顶空固相微萃取-气相色谱/质谱联用法研究枸桔中的香气化合物

采用顶空固相微萃取-气相色谱/质谱联用法分析了湖北江汉平原的枸桔中香气化合物以及其随枸桔成熟度的变化,以D-柠檬烯、α-蒎烯、芳樟醇、α-松油醇为代表,获得了顶空固相微萃取的最佳萃取条件。气相色谱-质谱(GC-MS)联用技术结果表明:从枸桔果肉中共检测出60种香气成分,其中烃类32种,酯类10种,醇类7种,醛类11种;从果皮中共检测出37种香气成分,其中烃类27种,酯类1种,醇类3种,醛类5种,其它类1种。生长初期、中期和成熟期的枸桔果肉共有的香气成分有14种,果皮共有的香气成分有13种,其中生长初期枸桔果实中的总香气含量最高。     

GC-O-MS法对酒花中香气活性成分的分析

采用顶空固相微萃取气相色谱-嗅闻-质谱((HS-SPME-GC-O-MS)联用的方法研究酒花中的香气化合物的组成和风味,并与传统的同时蒸馏萃取、水蒸气蒸馏方法进行比较,定性采用质谱谱库检索结合保留指数进行验证。结果表明:3种方法测得的1号酒花中的香气活性成分存在较大的差异,HS-SPME法最为适合,该法共鉴定出71种成分,占总峰面积质量分数的97.93%,以月桂烯、β-石竹烯为主要成分的萜烯类化合物共22种,其质量分数达88.73%,醇类及酯类质量分数分别为1.98%,3.42%。采用该方法对3个不同的酒花品种定性并嗅闻,能够嗅闻到的香气活性成分共计34种,包括碳氢化合物(包括萜烯)类7种,醇(酚)类11种,酯类10种,酮类2种,未知化合物4种。嗅闻结果表明,在1号、2号、3号3种酒花中分别嗅闻到了26,23,16种香气物质,其中重要的香气活性成分为β-香茅醇、β-石竹烯、里那醇、香叶醇、α-萜品醇、β-香茅醇、橙花醇、橙花椒醇、香叶酸甲酯、辛酸甲酯、乙酸香叶酯等。     

固相微萃取-气相色谱-质谱法分析香樟籽挥发性成分

采用固相微萃取-气相色谱-质谱法分离和鉴定香樟籽的挥发性成分,用归一化法测定其相对含量。共分离出76种组分,鉴定出47种化合物,其含量占总挥发性成分的97.4%。主要挥发成分为樟脑(57.89%)、柠檬烯(12.68%)、α-蒎烯(4.42%)、莰烯(2.69%)、香橙烯(2.34%)、伞花烃(2.26%)及β-蒎烯(2.12%)。     

保留指数结合准确质量测定对鱼腥草挥发性成分的定性分析

采用顶空-气相色谱-四极质谱法和顶空-气相色谱-飞行时间质谱法对鱼腥草挥发性成分进行检测,运用保留指数结合准确质量测定,分别从鱼腥草茎和叶中鉴定出49、39种挥发性组分,并采用峰面积归一化法测定各组分的相对含量。鱼腥草茎和叶中的挥发性成分差别较大。鱼腥草茎以α-蒎烯(12.24%)、β-蒎烯(22.42%)、月桂烯(11.98%)、乙酸冰片酯(10.97%)、甲基正壬酮(10.83%)为主要成分,而鱼腥草叶则以月桂烯(39.48%)、(Z)-β-罗勒烯(26.52%)、癸醛(10.35%)、桧烯(4.43%)、甲基正壬酮(2.44%)为主。结合保留指数和准确质量测定能显著提高质谱定性的准确性,有利于解决质谱检索时定性不确定的问题。     

用极微弱化学发光法评价萜类化合物的稳定性

在60℃氧气中,用极微弱化学发光法测定单萜类化合物的化学发光强度,通过化学发光强度评价了单萜类化合物对氧气的稳定性。萜烯类化合物的稳定顺序为:γ-松油烯<莰烯<异松油烯=α-松油烯<β-蒎烯<β-月桂烯<α-蒎烯=柠檬烯。萜醇类化合物的稳定顺序为:桃金娘醇<紫苏醇<α-松油醇<龙脑=香茅醇=薄荷醇。萜醛类化合物的稳定顺序为:桃金娘醛<紫苏醛。具有同样骨骼,不同官能团的单萜类化合物稳定顺序为:萜醛<萜醇<萜烯。     

同时蒸馏萃取-气相色谱/质谱法分析烟草中挥发性成分

本文对云南12种烟叶中挥发性成分进行提取分离,气相色谱/质谱测定.系统地对同时蒸馏萃取条件和色谱分离条件进行优化,结合谱库检索和匹配度定性方法鉴定149种化合物,并对其中的35种重要香气成分进行了定量分析,包括酮类7种、醇类6种、烯烃类4种、烟碱类3种、烷烃类2种、醛类2种、酯类2种、呋喃类2种等.该方法具有81.09％～97.45％的高回收率.结果表明,同时蒸馏萃取集采样、萃取、浓缩于一体,操作简单快速,适合于烟草中挥发性成分的提取,结合气相色谱/质谱联用仪(GC-MS)分离测定,能准确对挥发性成分进行定性和定量分析.     

阿育魏实挥发油成分的GC-MS分析

采用水蒸气蒸馏的方法提取了阿育魏实挥发油,并利用气相色谱一质谱联用技术对其化学成分做了分析,共鉴定出麝香草酚、β-伞花烃、萜品烯、α-崖柏烯、β-月桂烯和香芹酚等53个化合物。研究阿育魏实挥发油的成分,对民族药品质提升及原料的质量保证具有十分重要的意义。     

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.