环钯化二茂铁亚胺-膦配合物的电喷雾离子阱质谱研究

采用电喷雾离子阱质谱法(ESI-MS)对10种环钯化二茂铁亚胺-膦配合物的质谱特征进行了研究, 获得了其结构碎片信息, 对其质谱裂解途径进行了解析. 结果表明, 在正离子检测方式下可以得到强的准分子离子峰[M-Cl]+簇, 它们的(+) ESI-MSn(n=1~3)质谱主要产生碳-膦键断裂的碎片, 同时也能观察到Pd—P或Pd—C键的断裂, 这些特征为此类化合物及其结构类似物的结构推断提供了依据.     

新型环钯化二茂铁亚胺-膦配合物的质谱特征

采用电喷雾离子阱质谱法(ESI-MS)对两种环钯化二茂铁亚胺-膦配合物的质谱特征进行了研究,获得了它们的结构碎片信息,对其质谱裂解途径进行了解析.结果表明:在正离子检测方式下可以得到强的准分子离子峰[M-C l]+和[M-I]+簇,它们的(+)ESI-MSn(n=1~4)质谱主要产生碳-膦键断裂的碎片,同时也能观察到钯-磷键的断裂.这些特征为此类化合物及其结构类似物的结构推断提供了依据.     

乙二胺钴氧合反应的电喷雾串联质谱研究

采用电喷雾多级串联质谱技术对氧载体模型化合物乙二胺钴氧合产物的的质谱裂解规律进行了探讨。以固相法合成的乙二胺钴吸氧初和吸氧6 d两个阶段为研究体系,在正离子电喷雾质谱条件下能够清楚地观测到乙二胺钴氧合配合物的特征碎片离子。对其中m/z 150.86的碎片峰进行子离子扫描,可得到失去中性氧分子(M=32)的子离子碎片峰(m/z 118.85),从而可进一步确认其为氧合配合物碎片峰。本文采用电喷雾多级串联质谱技术对吸氧初和吸氧饱和后的两个体系进行了合理的初步探讨,根据所得质谱数据对乙二胺钴氧合产物的结构、裂解规律及氧气的存在形态给出初步合理的推论,结果表明,吸氧过程是一个老化的过程,乙二胺钴配合物从吸氧初到吸氧饱和后,其形态经历了从双核过氧桥联配合物到双核过氧羟基双桥联配合物形态的转变。初步确立电喷雾质谱(ESI-MS)可做为研究氧合反应和表征氧合配合物的有效技术手段。     

四棱草环肽C和D的ESIMS-MS分析

利用低能量碰撞诱导解离(CID)技术对四棱草环肽C和四棱草环肽D的电喷雾电离串联质谱(ESIMS-MS)进行了研究.ESIMS可以确定环肽的分子量,根据多级质谱中逐次失去氨基酸残基的碎片离子可以确定环肽中氨基酸残基的连接顺序.氨基酸残基主要从酰氨键C端断裂失去,有时亦会从N端断裂失去氨基酸残基.     

组氨酸钴氧合反应的电喷雾串联质谱

组氨酸合钴配合物是重要的氧载体模型化合物,对揭示氧载体的可逆吸氧机理的研究有着重要的作用。本文以组氨酸合钴吸氧初和吸氧中期两个阶段为研究体系,采用电喷雾多级串联质谱技术对组氨酸合钴氧载体的质谱裂解规律进行了研究。在其质谱裂解图谱中发现了氧合配合物碎片峰,将该氧合配合物碎片峰进一步裂解,可得到失去中性氧分子的子离子碎片峰,从而对其氧合形式进行了确认,根据所得质谱数据对组氨酸合钴氧合产物的结构、裂解规律及氧气的存在形态给出合理的推论。结果表明,吸氧过程是一个动态的变化过程,组氨酸合钴配合物吸氧初和吸氧24h后,分子氧均以超氧型形式存在,但其型态经历了从双核超氧桥联配合物到双核双桥联超氧羟基配合物的转变。对此过程的研究一直缺乏直接测定方法未被完全确定。本文采用电喷雾多级串联质谱技术对此氧合反应的机理进行了探讨,并初步确立电喷雾质谱（ESI-MS）可做为研究氧合反应和表征氧合配合物的有效技术手段。     

基于密度泛函理论的橘霉素衍生物质谱裂解行为研究

采用电喷雾离子阱质谱(ESI-IT-MSn),研究了橘霉素衍生物正离子模式下的裂解行为,并结合密度泛函理论(DFT)证明裂解途径的可靠性,为同类化合物的准确鉴定提供实验和理论基础。核磁共振仪对海莲内生真菌代谢产物分离得到的橘霉素衍生物结构进行确认,电喷雾离子阱质谱正离子模式扫描,测定化合物氢氘交换产物多级裂解质谱图,并结合键断裂能和Mulliken电荷分布,进一步验证裂解规律。实验结果表明,分子结构中-COOH和CH3COO-在一级裂解过程中易脱除CO2和COCH2,CID-MS2观测到丢失H2O/HDO、H2O和-CH3或CHCO/CDCO的碎片离子峰,且丰度依次降低,理论计算也证明,这些碎片离子的总能量依次增大,稳定性降低,键断裂能逐渐增大。该结果丰富了橘霉素衍生物的电喷雾质谱裂解规律,有助于橘霉素衍生物结构的准确鉴定,为该类化合物的检测和痕量分析提供了更多支持。     

氯代血红素的多级质谱研究(MS1～MS7)

在电喷雾离子阱质谱仪上,进行了氯代血红素的MS^1～MS^7 CID质谱研究。在各级碰撞诱导解离(CID)过程中,氯代血红素准分子离子[M-CI]的母环未发生碎裂反应,而与母环以碳碳单键相连的侧基依次失去。通过Hyperchem对氯代血红素分子结构的优化,对比各级质谱图,发现侧基的失去顺序与其键长有密切关系,键长越长,越优先失去。离子阱质谱仪的CID过程碰撞能量较低,有利于进行多级质谱分析,为得到母离子更详尽的结构信息提供了良好的条件。     

大黄酸ESI-IT MS质谱行为及碎片离子的量子化学研究

采用电喷雾-离子阱质谱(ESI-IT MS),获取大黄酸分子的一级质谱和多级质谱碰撞诱导解离下的碎片离子,以量子化学计算大黄酸分子及其主要碎片离子的质谱行为。通过对质谱离子几何参数、键断裂能、电荷变化、自旋密度以及前线分子轨道的分析,可得到m/z 282.8、256.9、238.9、210.8、192.8、182.8、166.8离子的稳定构型以及质谱裂解途径,从而较系统地解释了大黄酸分子在ESI-IT MS中的裂解行为。     

有机盐类化合物醋酸钠的电喷雾质谱研究

利用电喷雾质谱技术研究了有机盐类化合物醋酸钠(NaAc)的特征质谱行为,实验结果表明,在全扫描电喷雾正负离子谱中都出现了质量数相差82的质谱峰簇．这与醋酸钠的相对分子质量相一致,正负质谱峰簇分别对应于簇合物离子Na^ (NaAc)n和Ac^-(NaAc)m:簇合物离子的多级串联质谱进一步证明了簇合物离子的存在。该结果为类似结构的盐类化合物的表征提供了一种新的质谱证据。     

苦参中黄酮类化合物的电喷雾质谱研究

采用电喷雾多级串联质谱对苦参中黄酮类化合物二氢黄酮及二氢黄酮醇类化合物的特征质谱行为进行了研究.实验结果表明,两类化合物在电喷雾多级串联质谱条件下均可以在C环发生开环断裂,但断裂的位点不同;两类化合物生成的碎片离子也有很大差异,提出了由二氢黄酮醇类化合物C环上3位连接的-OH所诱发的不同反应过程的质谱碎裂机理.     

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%.     

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.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

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%).     

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.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.