A selective,tin-free radical mediated synthesis of indoles based on a sulfonate template

A synthesis of indoles based on a vinyl sulfonate template is described. The approach employs a sulfonate group which plays three discrete roles in the synthetic sequence. Firstly the highly electron-withdrawing sulfonate group behaves as an activating group for a 1,4-addition of an aniline to the unsaturated system. Secondly, the electron-withdrawing nature of the same group also allows it to behave as a radical stabilising group which facilitates radical cyclisation to an aromatic ring to yield a transient indoline. Finally, the pendant sulfonate group behaves as a leaving group to yield the indole.     

Bi-fluorescence-labeled maltoheptaoside: convenient substrate for continual assay of alpha-amylase

A new maltoheptaose derivative was prepared as a useful substrate for continual assay of alpha-amylase. The maltoheptaoside has thionaphtyl group as a fluorescent energy donor at the reducing end and dansyl group as an acceptor group at the non-reducing end. Excitation of the thionaphthyl group at 290 nm results in emission at 523 nm from the dansyl group, while the emission from the thionaphthyl group is quenched by the dansyl group. This fluorescence energy transfer is reduced by the hydrolytic action with alpha-amylase and a significant decrease in the dansyl emission concomitant with an increase in the thionaphthyl emission was observed. Usefulness of this substrate was demonstrated for sensitive and continuous assay of alpha-amylase from Aspergillus oryzae.     

Linear synthesis of a protected H-type II pentasaccharide using glycosyl phosphate building blocks.

A linear synthesis of a fully protected H-type II blood group determinant pentasaccharide utilizing glycosyl phosphate and glycosyl trichloroacetimidate building blocks is reported. Envisioning an automated solid-phase synthesis of blood group determinants, the utility of glycosyl phosphates in the stepwise construction of complex oligosaccharides, such as the H-type II antigen, is demonstrated. Installation of the central glucosamine building block required the screening of a variety of nitrogen protecting groups to ensure good glucosamine donor reactivity and protecting group compatibility. The challenge to differentiate C2 of the terminal galactose in the presence of other hydroxyl and amine protecting groups prompted us to introduce the 2-(azidomethyl)benzoyl group as a novel mode of protection for carbohydrate synthesis. The compatibility of this group with traditionally employed protecting groups was examined, as well as its use as a C2 stereodirecting group in glycosylations. The application of the 2-(azidomethyl)benzoyl group along with a systematic evaluation of glycosyl donors allowed for the completion of the pentasaccharide and provides a synthetic strategy that is expected to be generally amenable to the solid support synthesis of blood group determinants.     

2,2‐Bis(ethoxycarbonyl)vinyl (BECV) as a Versatile Amine Protecting Group for Selective Functional‐Group Transformations

A 2,2‐Bis(ethoxycarbonyl) vinyl‐ (BECV) group was used for the selective protection of amines at room temperature in the presence of potentially interfering functional groups such as OH, SH, COOH as well as other NH₂ groups. Several functional group transformations such as esterification, O‐alkylation, O‐acylation, N‐alkylation, N‐acylation, S‐alkylation can selectively be carried out in the presence of the BECV group. The selective deprotection of the BECV group was achieved in a short time using ethylenediamine at room temperature while several other functional groups such as benzoate, aliphatic esters, amides and ethers remain intact. The BECV group shows orthogonal stability against the common protecting groups such as Fmoc, Cbz and Boc.     

超声心动图联合动态心电图检查对急性心肌梗死诊断和预后评估的价值

为探讨超声心动图联合动态心电图检查在急性心肌梗死(AMI)患者诊断和预后评估中的应用价值,本研究选取2016年6月~2018年6月我院收治并确诊的100例AMI患者作为观察组,另选取同期100例非冠心病患者作为对照组。以AMI患者心源性死亡为终点事件,将观察组分为死亡组(n=15)和存活组(n=85)。所有患者均采用飞利浦IU-Elite及EPIQ5彩色多普勒超声诊断仪进行超声心动图检查,采用DMS-3004A进行标准的12导联动态心电图检查。比较各组患者心率震荡指标[震荡起始(TO)、震荡斜率(TS)]、心率变异性指标[NN间期标准差(SDNN)、QT离散度(QTd)、经心率校正的QT离散度(QTcd)]及心功能指标[左心室舒张末期内径(LVEDD)、左心室射血分数(LVEF)]水平的变化。结果显示,观察组TO、QTd、QTcd、LVEDD均明显高于对照组,TS、SDNN、LVEF均明显低于对照组,差异有统计学意义(P<0.05)。死亡组TS、SDNN均明显低于存活组,差异有统计学意义(P<0.05);死亡组TO高于存活组,QTd、QTcd、LVEF、LVEDD均低于存活组,但差异无统计学意义(P>0.05)。本研究结果表明,AMI患者心率震荡(HRT)明显减弱甚至消失,HRV、LVEF明显降低,LVEDD、QTd明显增大,QT间期明显延长。超声心动图和动态心电图联合检查对AMI患者诊断及预后评估均有重要的临床应用价值。     

CDFI鉴别男性乳腺良恶性肿瘤价值及与CXCL1、Gab2、MVD的相关性探究

本研究选取18例男性乳腺恶性肿瘤患者作为研究组,纳入同期41例男性良性乳腺肿瘤及50例健康体检男性分别作为良性对照组和健康对照组,通过对比分析发现,研究组CDFI参数[搏动指数(PI)、阻力指数(RI)、血流速度(PSV)]高于良性对照组和健康对照组(P＜O.05);PI、RI、PSV联合诊断男性乳腺恶性肿瘤的AUC高...     

Introduction of a hydroxy group at the para position and N-iodophenylation of N-arylamides using phenyliodine(III) bis(trifluoroacetate)

The reaction of anilides with phenyliodine(III) bis(trifluoroacetate) (PIFA) in trifluoroacetic acid (TFA), TFA-CHCl3, or hexafluoroisopropyl alcohol (HFIP) is described. When the acyl group of the anilide is highly electronegative, such as trifluoroacetyl, or the phenyl group is substituted with an electron-withdrawing group, the 4-iodophenyl group is transferred from PIFA to the amide nitrogen to afford acetyldiarylamines. On the other hand, when the acyl group contains an electron-donating function, such as 4-methoxyphenyl, or the phenyl group is substituted with an electron-donating group, a trifluoroacetoxy group is transferred to the para position of the anilide aromatic ring. This group is hydrolyzed during workup to produce the corresponding phenol.     

Aspects of Electrochemical Behavior of Aldehydes and Ketones in Protic Media

Reduction of carbonyl group in aldehydes and ketones, as well as oxidation of numerous aldehydes is discussed, as well as those reductions of organic compounds where the C?O group activates cleavage of an adjacent C? X bond where X is a good leaving group like halogen, OH, NH₂ or SR or activates hydrogenation of an adjacent C?C group. Survey involves aliphatic and aromatic aldehydes, aryl alkyl and diaryl ketones, as well as α‐ketoacids, 1,2‐diketones and compounds where the carbonyl group is a part of a ring. The role of acid–base, hydration–dehydration and in some cases keto–enol equilibria on electrochemical behavior is pointed out, as well as the role of buffer kind and concentration and the nature of the cation of supporting electrolyte. Better understanding of these factors promises finding of best conditions for electroanalytical procedures.     

群的对称性偶合系数计算的新方法

本文根据群G和子群g的不可约表示基向量标准化的性质,提出了直接计算子群g的V系数和W系数的新方法。对于SO(3)群-点群的情况,可由标准化基向量与尽可能低j值的SO(3)群-点群V系数和变换系数,以及3j、 6j符号等关系,分别导出计算点群V系数和W系数的公式。并以正二十四面体Ih群为例,计算了三角组分系、五角组分系的所有V系数和W系数,计算结果列于附表。     

Catalytic applications of transition-metal complexes bearing diphosphinidenecyclobutenes (DPCB)

The preparation and characterization of sterically protected diphosphinidenecyclobutenes bearing two two-coordinate phosphorus atoms are described from the viewpoint of the development of a novel type of bidentate ligand for transition-metal complexes. They form complexes with group 6 metals such as chromium, molybdenum and tungsten, group 8 metals such as ruthenium, group 10 metals such as palladium and platinum, and group 11 metals such as copper and gold. Some of them can be used as catalysts for synthetic reactions such as cross-coupling of the Sonogashira type, Suzuki-Miyaura coupling, Ullmann coupling, Kosugi-Migita-Stille coupling, cyanation, polymerization of ethylene, dehydrogenative hydrosilylation of ketones, hydroamination of 1,3-butadienes, and direct alkylation or amination of allylic alcohols of Tsuji-Trost reactions.     

High temperature resistant tailor‐made poly(meth)acrylates bearing adamantyl group via atom transfer radical polymerization

This investigation reports preparation of tailor‐made poly(meth)acrylates bearing adamantyl group using atom transfer radical homo and copolymerization via initiator as well as via monomer approach. The ATRP of methyl methacrylate was investigated using different initiators having adamantyl group (like AdMBr or AdBr) as well as conventional EBiB initiator and CuBr as catalyst in combination with PMDETA as ligand. It was observed that the incorporation of the bulky adamantyl group increased the rate of polymerization. The polymerization proceeded through first‐order kinetics and molecular weights increased linearly with conversion, close to the targeted molecular weights. The living nature of the end‐group was confirmed by MALDI‐TOF‐mass spectrometry and chain extension experiment. The homopolymerization of adamantyl methyl acrylate (AdMA) and its copolymerization with MA was successfully carried out using methylbromopropionate (MBrP) as initiator and CuBr/dNbpy as the catalyst. Interestingly, the resultant poly(meth)acrylates bearing the adamantyl group had excellent thermal stability and much better thermal stability than the similar polymers without adamantyl group as evidenced from thermogravimetry analysis (TGA) and isothermal TGA studies. Importantly, incorporation of adamantyl group “adamantly” increases rate of polymerization, thermal stability, and glass transition temperature of the polymers. All the polymers were characterized by NMR, MALDI‐TOF‐MS, DSC, and TGA analysis. © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7101–7113, 2008     

Block copolymers and telechelic oligomers by end group reaction of polymethacrylates

Block copolymers and telechelic oligomers bearing methacrylate moities were obtained by means of a new highly selective end group reaction. Starting from polymethacrylates that were prepared by radical polymerization in the presence of mercaptanes as chain transfer agents, the resulting ester end group linked to the terminal tertiary carbon atom of the polymer backbone can be either transesterified or saponified selectively. The selectivity of the end group reactions was determined by MALDI-TOF-mass spectrometry. Polymethacrylate-b-poly(ethylene oxide)-, polymethacrylate-b-poly(methacrylic acid)- and polymethacrylate-b-polysiloxane-b-polymethacrylate-copolymers as well as α,ω-dihydroxy- and α,ω-dicarboxy-telechelic polymethacrylates were prepared by applying end group transesterification or end group saponification.     

Recent advances on carborane-based ligands in low-valent group 13 and group 14 elements chemistry

Carboranes are a class of polyhedral boron-carbon molecular clusters, they can serve as versatile ligands in stabilizing low-valent main group element compounds, due to their exceptionally thermal and chemical stabilities, easy modifications at the cage carbon vertices, as well as large spherical steric effects. These carborane-based ligands provide interesting opportunities for the synthesis of low-valent main group element compounds with novel structure and reactivity, which indeed enrich the ...     

cis-Tetrahydrofuran-3,4-diol structure as a key skeleton of new protecting groups removable by self-cyclization under oxidative conditions

A variety of carbonate-type acyl groups having a cis-tetrahydrofuran-3,4-diol (1,4-anhydroerythritol) backbone structure and a TrS or MMTrS group have been examined as new "protected" protecting groups of the 5'-hydroxyl group of nucleosides. These acyl groups were designed in a manner where they could be deprotected by I(2)-promoted removal of the TrS or MMTrS group followed by self-cyclization involving an intramolecular attack of the once-generated neighboring hydroxyl group on the acyl carbon. It turned out that these acyl groups could be introduced into the 5'-hydroxyl group of a 3'-O-protected thymidine derivative by use of the corresponding acyl imidazolides or 4-nitrophenyl esters as well as by reaction with carbonyldiimidazole or 4-nitrophenyl chloroformate. Among the acyl groups tested, it was found that the CTFOC group could be easily introduced into the 5'-hydroxyl group of 3'-masked deoxyribonucleoside derivatives and rapidly removed under mild conditions using iodine.     

Studies on the hydrogen bonding of aniline's derivatives by FT-IR

The hydrogen bonding of 23 aniline's derivatives in various solvents and in solid states are studied by Fourier transform infrared spectroscopy. The Infrared absorption of their amino group is greatly influenced by solvents. Compared with those data determined in hexane, the symmetric stretching frequency (nu(s)) and asymmetric stretching frequency (nu(as)) of amino group have an obvious bathochromic shift in benzene, but a relatively smaller shift in CCl4. It is also found that the concentration of these compounds has very little effect on the frequencies, the band shapes and relative absorption intensities of amino group. This indicates that the intermolecular hydrogen bonds are very weak between the aniline's derivatives in the solution. The substituent of methyl (-CH3) has different electronic effects in organic solvents with various polarities. Methyl group behaves as an electron-donating functional group in hexane, however, it shows an electron-withdrawing effect in benzene. When methoxyl (CH3O-) is ortho-substituted, v(as) of amino group increases and nu(s) almost does not change. While methoxyl (CH3O-) is meta-substituted, v(as) of amino group increases, but nu(s) decreases. The groups of chloro- (Cl-) and nitro- (-NO2) cause a hyposochromic shift of the nu(as) and nu(s) of amino group, while substituent of -NH2 makes a bathochromic shift. The solvents influence the relative intensities of nu(as) and nu(s) of amino group more greatly than the substituents do. In solid states, the amino group of aniline's derivatives has more than two absorption bands because of forming the inter- or intra-molecular hydrogen bonds.     

Weakly coordinating group directed rhodium-catalyzed unconventional site-selective C-H olefination of indolizines at the 8-position

A rhodium-catalyzed directing group promoted selective C-H olefination reaction of indolizines at the 8-position is re ported.Di-olefination at 2,8-positions also achieved with silver hexafluoroantimonate as an additive under similar reaction conditions.Weakly coordinating groups,such as ketone,alde hyde,amide and ester,were used as directing groups.The ester group can be removed under acid conditions and therefore is used as a traceless directing group.     

New Protecting Group Strategies for the Solid-Phase Synthesis and Modification of Peptides,Oligonucleotides, and Oligosaccharides

Blocking and activation can be achieved with protecting groups such as the ortho-nitrobenzenesulfonyl group (see picture). In solid-phase peptide synthesis, this group can be used for temporary protection (path A) as well as the activation and selective N-alkylation (path B) of an amino group.     

细菌性阴道病与甲硝唑治疗对妊娠结局的影响探讨

目的探讨细菌性阴道病和甲硝唑治疗对妊娠结局的影响。方法选取吉水县醪桥镇人口与计划生育服务所2014年7月至2015年7月收治的120例中晚期妊娠合并BV者,根据自愿原则分为治疗组和未治疗组(C组)。治疗组中口服用药为A组,阴道用药为B组。结果治疗组中两种不同用药方式都对妊娠合并BV患者有着显著的治疗效果,两组比较无统计学意义(P0.05);治疗组妊娠结局总不良率仅为10%,未治疗组中总不良率高达73.3%,对比差距显著,具备统计学意义(P0.05)。结论对妊娠期合并细菌性阴道病妇女使用甲硝唑治疗,对提升妊娠期妇女生活品质和降低不良妊娠风险有着关键的作用,同时具有十分重要的参考意义。     

Simultaneous protection and activation of amino acids using propargyl pentafluorophenyl carbonate

[reaction: see text] A very efficient method for the simultaneous protection of the amino group and activation of the carboxyl group of amino acids is reported using propargyl pentafluorophenyl carbonate (PocOPfp). The amino group is protected as a propargyloxycarbonyl (Poc) derivative, and the carboxyl group is activated as a pentafluorophenyl ester. The yields obtained are good to excellent ranging from 60 to 87%.     

Thermosensitive gels incorporating polythioether units for the selective extraction of class b metal ions

Novel temperature-responsive copolymers of N-isopropylacrylamide and monoaza-tetrathioether derivative, were synthesized for the selective extraction of soft metal ions such as silver(I), copper(I), gold(III) and palladium(II) ion. The ratio between N-isopropylacrylamide group and monoaza-tetrathioether group in the copolymer was determined. The ratio between N-isopropylacrylamide group and monoaza-tetrathioether group varied in the range of 66:1–187:1. Each lower critical solution temperature (LCST) of the polymer solution was determined spectrophotometrically by the relative absorbance change at 750 nm via temperature of the polymer solution. Metal ion extraction using the copolymer with appropriate counter anions such as picrate ion, nitrate or perchlorate ion was examined. Soft metal ions such as silver(I), copper(I), gold(III) and palladium(II) ion were extracted selectively into the solid polymer phase. The extraction efficiency of a metal ion such as silver ion increased as the increase of the ratio of the monoaza-tetrathioether group to N-isopropylacrylamide group in the polymer. The quantitative extraction of class b metal ions as well as the liquid–liquid extraction of metal ions with monoaza-tetrathioether molecule was performed.