月腺大戟中二萜类化学成分的大气压化学电离-串联质谱研究

利用大气压化学电离源多级串联质谱(APCI/MSn)方法对月腺大戟中的松香烷型二萜类成分,以及苯乙酮类成分进行了分析鉴定。根据串联质谱数据,共鉴定出7个化合物,分别为岩大戟内酯B、对映体-11α-羟基松香烷-8(14),13(15)-二烯-16,12α-内酯、岩大戟内酯A、月腺大戟甲素、月腺大戟乙素、狼毒乙素、3,3′-二乙酰基-4,4′-二甲氧基-2,2′,6,6′-四羟基二苯甲烷,并获得了相应化合物的结构信息。该方法可简便、快速鉴定月腺大戟有效成分。     

锦灯笼果实的化学成分研究

从锦灯笼中分离得到5个甾体类化合物,分别鉴定为酸浆素A(1,alkekengilin A)、酸浆素B(2,alkekengilin B)、酸浆苦素D(3,physalin D)、酸浆苦素P(4,physalin P)、4,7-二去氢新酸浆苦素B(5,4,7-didehydro-neophysalin B).其中酸浆素A(1,alkekengilin A)和酸浆素B(2,alkekengilin B)为新的天然产物.运用现代波谱技术对上述化合物的结构进行了确证.     

美丽红豆杉二萜的研究 I: 美丽红豆杉素A, B和C的结构测定

从美丽红豆杉(Taxus mairei)的茎皮中分离得三个新的二萜化合物, 其中美丽红豆杉素A(taxamairin A, 1)和美丽红豆杉素B(taxamairin B, 2)是含有 酮的三环二萜,它们的骨架尚未见文献报道; 美丽红豆杉素C(taxamairin C, 3)是含有半缩酮的四环二萜. 结构鉴定应用了高分辨的^1H NMR, ^1^3C NMR ^1H-^1H COSY和DFNOE等方法. 美丽红豆杉素A的结构还通过X射线单晶衍射予以证实.     

美丽红豆杉二萜的研究 Ⅰ.美丽红豆杉素A,B和C的结构测定

从美丽红豆杉(Taxus mairei)的茎皮中分离得三个新的二萜化合物,其中美丽红豆杉素A(taxamairin A,1)和美丽红豆杉素B(taxamairin B,2)是含有(艹卓)酮的三环二萜,它们的骨架尚未见文献报道;美丽红豆杉素C(taxamairin C,3)是含有半缩酮的四环二萜.结构鉴定应用了高分辨的~1H NMR,~(13)C NMR ~1H-~1H COSY和DFNOE等方法.美丽红豆杉素A的结构还通过X射线单晶衍射予以证实.     

红纹马先蒿中木脂素衍生物成分研究

红纹马先蒿(Pedicularis striata)是玄参科马先蒿属植物,其主要成分为苯丙素甙。本文报道对该植物进一步研究中分离得到的2个微量甙类化合物,命名为红纹马先蒿甙A和B[Striatoside A(1)和B(2)]。     

仙茅素A的全合成

首次报道了仙茅素A[2,5-双(3,4-二羟基苯基)呋喃-3-甲醛]的全合成。以3,4-二甲氧基苯乙酮为起始原料,经Paal-Knorr反应,选择性溴代及还原等反应合成了仙茅素A,其结构经1H NMR,13C NMR和ESI-MS表征。     

月光花素甲(Ⅰ)、(Ⅱ)整体分子结构的测定

本文对月光花素甲(Calonyctin A)的整体分子结构分析加以完善并进行总结。前文报道月光花素甲是两个分子量相差28a.m.u的糖甙类同系物分子的混合物。这两个分子(简称M_1和M_2)分别称为月光花素甲(Ⅰ)与月光花素甲(Ⅱ)(Calonyctm A_1,CalonyctinA_2),分子量分别为938与910。它们分别含     

狼毒乙素分子印迹膜荧光传感器的制备及在中药材检测中的应用

以狼毒大戟根部提取的狼毒乙素(ECB)为模板分子, 7-二乙氨基香豆素-3-羧酸与3-溴丙烯缩合生成的烯丙端基香豆素类化合物(DCAC)为荧光单体, 丙烯酰胺为功能单体, 乙二醇二甲基丙烯酸酯为交联剂, 偶氮二异丁腈为引发剂, 通过自由基聚合制备了具有强烈青色荧光, 并且可以选择性富集狼毒乙素的分子印迹膜荧光传感器(FL-MIF). 研究结果表明, FL-MIF吸附ECB的线性范围为1.00~50.00 μmol/L, 在线性范围内, 随着ECB浓度递增, 青色荧光(489 nm)呈现出明显的荧光猝灭响应, 狼毒乙素的检测限为0.29 μmol/L. FL-MIF对ECB具有良好的特异选择性识别性能, 印迹因子为3.58, 明显高于类似结构的2-甲氧基-4-羟基苯甲酸(MHBA)、 没食子酸(GA)和3,3'-二乙酰基-4,4'-二甲氧基-2,2',6,6'-四羟基二苯基甲烷(DDTPM). 重复再生性能优异的FL-MIF可应用于实际样品中药材狼毒大戟ECB含量的检测.     

粤北产五味子科植物风沙藤的化学成分研究(Ⅱ)

本文继续报道从粤北所采集的五味子科植物风沙藤(Schisandra viridis A.C Sm)的根和茎中分得的另外三个木脂素类新化合物,即五味子酯(schisantherin)K(1),五脂酮(schisanlignone)E(2)和异安五脂素(isoanwulignan)(3)。通过光谱分析和化学转变,确定了它们的结构和构型。     

长苞铁杉中两个新的重排羊毛甾烷型三萜

从中国特有植物长苞铁杉树枝的甲醇提物中分离得到2个新的重排羊毛甾烷型三萜,命名为铁杉内酯素A(1)和铁杉内酯素B(2),其结构通过HR-ESIMS,1D和2D NMR等光谱技术确定,铁杉内酯素A(1)的构型进一步通过X单晶衍射确认.     

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.     

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.     

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.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Catalyst free,visible-light promoted photoaddition reactions between C60 and N-trimethylsilylmethyl-substituted tertiary amines for synthesis of aminomethyl-1,2-dihydrofullerenes

An efficient and benign method for the preparation of aminomethyl-substituted fullerenes has been developed. The process, involving catalyst free, visible-light irradiation of 10% EtOH-toluene solutions containing fullerene C₆₀ and N-trimethylsilylmethyl-substituted amines by using a 20 W compact fluorescent lamp, leads to formation of aminomethyl-substituted fullerene adducts in a highly efficient manner. The photoaddition reaction takes place via a pathway initiated by visible light absorption by C₆₀, followed by SET from the amine to the triplet excited state of C₆₀. Ethanol-promoted desilylation of the resulting a minimum radical then generates the corresponding α-amino radical which couples with the C₆₀ radical anion to form the anion precursor of the fullerene adducts. The new approach using visible-light takes place under mild conditions and it does not require the use of photocatalysts. Thus, the method developed in this effort could broadens the range of functionalized fullerene derivatives that can be readily prepared.     

Highly efficient and stereoselective cycloaddition of nitrones to indolyl- and pyrrolylacrylates

The reactions of various nitrones with indolyl- and pyrrolylacrylates proceeds regioselectively with high diastereoselectivity in the case of aldonitrones, and represents an effective method for obtaining new indolyl- and pyrrolyl-substituted isoxazolidine carboxylates stabilized by weak (CH?O) and moderate (NH?N) strength intramolecular hydrogen bonding. The resulting cycloadducts exhibit promising in vitro anti-influenza activities.     

Transition metal-free direct amination of benzoxazoles using formamides as nitrogen sources

A transition metal-free method for the direct amination of benzoxazoles using formamides as nitrogen sources is reported, which was mediated by an inexpensive and environmentally friendly tetrabutylammonium iodide/tert-butyl hydroperoxide system and gave the 2-aminobenzoxazole derivatives with moderate to good yields.     

l-Proline-catalyzed five-component domino reaction leading to multifunctionalized 1,2,3,4-tetrahydropyridines

Multifunctionalized 1,2,3,4-tetrahydropyridines are concisely synthesized in good yields via l-proline-catalyzed or l-proline/FeCl₃-cocatalyzed one-pot multicomponent reactions (MCRs). The MCRs involve a domino hydroamination/prins reaction/Mannich-type reaction/intramolecular dehydration-cyclization process. The molecular structure of 5baa, one of multifunctionalized 1,2,3,4-tetrahydropyridines, was confirmed by single-crystal X-ray diffraction.