L-苏式二氢鞘氨醇的立体选择性合成

二氢鞘氨醇（ＤＨＳ）是２－氨基－１，３－二羟基的饱和长链氨基醇化合物，是构成鞘脂类（包括鞘磷脂和糖鞘脂）的主链部分．由于鞘脂类在自然界中来源稀少，又很难得到纯品．因此，作为鞘脂类主链部分的二氢鞘氨醇的合成有重要的意义［１］．二氢鞘氨醇有两个手性碳，共...     

鞘氨醇的化学

动植物细胞中鞘脂及其代谢产物鞘氨醇等具有多种生理作用，是生命体传递信息的化学信使。鞘氨醇等的合成在有机合成界形成了一个经久不衰的热潮，应用各种新技术的合成方法不断出现。本文主要综述了鞘氨醇等衍生脂质的化学研究，特别是它们的化学合成进展。     

鞘氨醇激酶的相关抑制剂研究进展

鞘氨醇激酶(SphK)是脂质激酶,其作为癌症生物学中的重要限速酶受到了广泛的关注.它们通过产生鞘氨醇-1-磷酸(S1P)参与多种信号通路的调节,而S1P可介导细胞生长、分化、迁移和血管生成等多种生物学功能.目前鞘氨醇激酶抑制剂的研究是国内外研究的热点,并且随着鞘氨醇激酶1 (SphK1)晶体结构的解析,更多高选择性、高活性的抑制剂被开发出来.本文综述了具有抗肿瘤作用的与鞘氨醇激酶通路相关的抑制剂的研究进展.     

从D-甘露糖醇合成(2S, 3R)-鞘氨醇

以D-甘露糖醇为原料, 在制得了(2E)-4, 5-氧异亚丙基戊烯酸酯(5)以后,经不对称双羟基化反应、环硫酸酯化和叠氮化钠区域选择性开环等12步反应以7.7%的总产率合成了标题化合物的2, 3-二苯甲酰产物, 由此为鞘氨醇和神经鞘脂类化合物的合成开辟了又一新的途径。     

降解溴氨酸的鞘氨醇单胞菌N1菌株的固定化研究

用聚乙烯醇(PVA)做载体，用包埋法固定降解溴氨酸(学名为1-氨基-4-溴蒽醌-2磺酸，简称ABA)的鞘氨醇单胞菌(Sphingomonas sp.)N1菌株，并对固定化菌的制备条件及固定化菌降解溴氨酸的一般性质进行了研究．实验结果表明，细胞固定化以后的溴氨酸降解速度明显高于游离细胞，反应遵循一级反应动力学，反应的最适pH和温度范围明显变宽．固定化细胞的储存稳定性也高于游离细胞，4℃储存50d后，其对溴氨酸的降解率仍在99％以上，而游离细胞仅为7．4％．固定化细胞经过50次重复使用后，对溴氨酸仍具有很高的降解活性．     

HPLC-ICP-MS或HPLC-FAAS法分离测定硒化合物（英文）

提出了一种用高效液相色谱（HPLC）分离和用电感偶合等离子体质谱仪（ICP－MS）或火焰原子吸收光谱仪（FAAS）作元素专一检测器在线测定硒的化学形态的方法。在优化的HPLC条件下,用ESAⅢ阴离子色谱柱（250mm×4．6mm）,以柠檬酸铵为流动相（5．5mmol／L,pH5．5,流速1．5mL／min）,进样量100μL,分离和测定三甲基硒离子、硒代蛋氨酸、亚硒酸和硒酸盐只需8min。HPLC－FAAS在线分析4种硒化合物的检测限为p（Se）=1mg／L。用超声雾化器作ICP－MS的接口,HPLC－ICP－MS在线分析4种硒化合物的检测限分别为P（Se）=0．34μg／L（亚硒酸）,0．18μg／L（硒代蛋氨酸）,0．08μg／L（三甲基硒离子）和0．07μg／L（硒酸盐）。与气动雾化器接口相比,信号强度增加7至31倍。     

测定尿中痕量碘的高锰酸钾-亚砷酸体系催化光度法

在硫酸和磷酸的介质中,碘离子催化高猛酸钾与亚砷酸反应生成的锰（Ⅲ）氧化砷酸的反应,据此建立了催化光度法测定痕量碘的新方法。该法的检出限为0．4μg/L,测定的线性范围为1．0－25．0μg/L。应用该法测定了尿样中痕量碘的含量,获得了满意的结果,测定样品的相对标准偏差（n＝6）为2．5％－3．7％,加标回收率为96．4％－102．6％。     

红景天中红景天甙和酪醇的毛细管电泳法分析

利用毛细管电泳法分离测定两种红景天中红景天甙和酪醇的含量,所用毛细管规格为48.5cm×50μm,二极管阵列紫外检测器(DAD)检测波长221nm,最佳分离条件:电压21kV,分离温度25℃,背景电解质为含有30mmol/L十二烷基硫酸钠(SDS),2.5+97.5(V/V)乙腈的14mmol/L硼酸溶液,pH10.7。红景天甙与酪醇分别在60.0～7.5μg/mL和27.5～3.5μg/mL质量浓度范围内与电泳峰面积呈现良好线性关系,检测下限分别为3.0和1.5μg/mL。对标准品进行6次测定,迁移时间的RSD为0 25%和0 39%,峰面积的RSD为5 26%和3 52%。     

尿样中神经性毒剂代谢产物的HPLC/Q-TOFMS/MS检测方法研究

建立了尿样中甲基膦酸单乙酯(EMPA)、甲基膦酸单异丙酯(IMPA)、甲基膦酸频哪基酯(PMPA)3种神经性毒剂代谢产物的HPLC/Q-TOFMS/MS检测方法。以StrataSi-1型固相萃取小柱对尿样中的3种神经性毒剂代谢产物进行分离,HPLC/Q-TOFESIMS/MS进行测定,内标法定量。该方法对EMPA、IMPA、PMPA的线性范围均为5～320μg/L,相关系数均不低于0.9974;EMPA、IMPA、PMPA的加标回收率分别为57%、98%、81%;检出限(S/N≥3)均为0.1μg/L,定量下限(S/N≥10)均为1μg/L。并将该方法应用于禁化武组织(OPCW)首次生物医学样品分析演练未知尿样的检测,结果满意。     

鞘氨醇／胆固醇单层分子膜的热力学特性及表面形态的AFM观测

脂筏是近年来在生物膜研究中发现的一种富含鞘脂、胆固醇和特殊蛋白质的动态微区结构,其结构和功能的改变,会引发多种疾病．本文利用LB膜技术模拟脂筏的动态微区结构,通过测量表面压力与平均分子面积（π-A）曲线数据,计算出鞘氨醇／胆固醇LB单层膜的过量分子面积（△A（ex））、表面过量吉布斯自由能（△G（ex））、活度系数（f1和f2）以及弹性模量（Cs^-1）,系统的研究了二元组份混合单层膜的热力学特性,并用原子力显微镜对鞘氨醇与胆固醇混合膜的形态进行观察．热力学分析表明过量分子面积和过量吉布斯自由能相对理想状态都具有负偏差作用,这说明分子间相互作用表现为吸引力,且单层膜的稳定性、弹性模量和活度系数的数值明显的依赖于胆固醇与鞘氨醇的比例．AFM观察结果表明,纯鞘氨醇单分子膜表现为小的颗粒体结构;当鞘氨醇与胆固醇按不同摩尔比混合时,随着胆固醇摩尔比例的增加,混合膜呈现出从链状结构向较大的片层与网状共存结构的转化．最终纯胆固醇形成高度紧密的膜结构．AFM实验有力的支持了理论分析的结果．     

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%).     

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.     

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.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

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.