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.     

Gear effect—10 : Conformational aspects of the positive or negative buttressing effects of methyl groups: polymethylpyridines

The effect of the shape of a methyl group on reactivity, which cannot be accounted for by considering a methyl group as a spherical substituent with the appropriate van der Waals radius, was considered in kinetics of alkylalion of substituted pyridines and barriers to rotation and ground state conformations of an isopropyl group attached to a planar framework. The perturbation of a methyl group by an o-methyl group is accounted for by a unique conformational explanation which involves the polyhedral shape of the methyl group.     

The effect of molecular structure on the thermal properties of ferroelectric liquid crystalline cyclic siloxane tetramers

A series of liquid crystalline cyclic siloxane tetramers was prepared to investigate, in a systematic manner, the role of molecular structure of (a) the spacer group, (b) the mesogenic side group and (c) the chiral end group, on the liquid crystalline behaviour of these novel tetramers. The results from this systematic structure/property correlation study clearly showed the effects of the structure of the chiral end group and the mesogenic side group on the thermal stability and temperature range of the SmC* phase (ferroelectric) exhibited by these materials. For a given chiral end group, the effect of the length of the spacer group on the thermal stability and temperature range of the SmC* phases depended greatly on the structure of the mesogenic side group. By appropriate choice of spacer group, mesogenic side group and chiral end group, a number of tetramers exhibiting wide SmC* ranges (ferroelectricity) from below room temperature were synthesized.     

肾炎及肾衰患者血中金属元素含量的变化

用原子吸收法或极谱法测定了对例慢性肾炎病人（A组）和24例慢性肾衰病人(B组)及40名健康人（对照组，C组）全血中的Fe、Zn、Cu、Mn、Se、Pb和Ga含量。结果表明，A组与C组比较．血中Fe的含量A组明显低于C组（P＜0.05），Zn、Mn和Se的含量A组均非常明显低于C组（P＜0.01），Pb含量A组非常明显高于C组（P＜0．01），Cu和Ca含量两组间均无明显差异（P＞0.05）；B组与C组比较，Fe含量B组明显低于C组（P＜0.06），Se含量则B组明显高于C组（P＜0.05）；Zn、Mn、Cu、Ga含量B组均非常明显低于C组（P＜0.01），而Pb含量则B组非常明显高于C组（P＜0．01）。     

Synthesis of enantiomerically pure (S)-methanocarbaribo uracil nucleoside derivatives for use as antiviral agents and P2Y receptor ligands

We have developed an approach toward enantiomerically pure (S)-methanocarba ribonucleosides based on several functional group transformations on a sensitive bicyclo[3.1.0]hexane system. D-ribose was transformed into methanocarba alcohol 3 followed by conversion of the OH group to a nitrile with inversion of configuration at C4. The nitrile group was subsequently reduced in two stages to the 5'-hydroxymethyl group. An ester group appended to a tertiary carbon (C1) was transformed to an amino group as a nucleobase precursor.     

Synthesis of 4-alkoxy-8-hydroxyquinolines

Quinolines with a hydroxyl group at the 8-position and an alkoxy group at the 4-position are rare compounds. In this paper the synthesis of five 4-alkoxy-8-hydroxyquinolines is reported. The key reaction in the synthetic route is a selective protection of the hydroxyl group at C-atom 8 in 4,8-dihydroxyquinoline with a tosyl group and the hydrolytic removal of the protective group after the alkylation. The tosyl group is stable during the alkylations with various alkylating agents in the presence of sodium hydride.     

Multisite Solid Catalyst for Cascade Reactions: The Direct Synthesis of Benzodiazepines from Nitro Compounds

Substituted 1,5‐benzodiazepines are selectively synthesized in one pot from substituted nitroaromatics and ketones. The reaction is performed in the presence of hydrogen and in the absence of solvent by using a bifunctional solid catalyst with a chemoselective hydrogenation functional group capable of reducing the nitro group to a diamino group and an acid functional group, which catalyzes the cyclocondensation of the amino group with the ketone.     

螺旋型高分子链晶体结构所属空间群的演变规律性

本文利用有色对称的理论讨论了螺旋型高分子链晶体结构所属空间群的演变规律性。得出：（１）有序链结构的空间群是无序链结构空间群的有色空间群；（２）对称性较低的螺旋链所属空间群是高对称螺旋链所属空间群的有色空间群；（３）从而得出空间群演变的方向、途径和结果，总结出其演变的规律性。     

Synthesis of block copolymer containing dextran and polyamide sequences

A novel AB-type block copolymer composed of dextran and polyamide sequences was prepared through the following two approaches. One is a coupling reaction of a terminal functional group introduced in the dextran chain with that in the polyamide chain, such as the reaction of an amine group with an acyllactam group or that of a lactone group with an amine group at the corresponding chain ends. The other is an anionic polymerization of a bicyclic lactam activated with a trimethylsilylated dextran derivative having an acyllactam end group. The latter procedure was found to be more effective for the preparation of the block copolymer having a high molecular weight polyamide sequence.     

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.     

The effect of bridge group on the thermal stability of nitro-substituted aromatic polyamides

The effect of introducing a bridge group into the diamine moiety on the thermal stability of aromatic polyamides substituted with a nitro group in the diamine ring at the ortho position to the amide group was studied. Our present work showed that the bridge group, whether it was electron withdrawing or releasing, did not have a significant effect on the activity of the nitro group for the intramolecular cyclization reaction to poly(benzoxazole)s.     

Improvement of stability of phenacyloxycarbamidomethyl (Pocam) group,a cysteine protecting group removable with zinc reduction,under acidic conditions

In order to improve the stability of phenacyloxycarbamidomethyl (Pocam) group, a cysteine protecting group removable with zinc reduction, under acidic conditions, various alkyl substituents on the nitrogen atom of Pocam group were examined. As a result, attachment of an electron-withdrawing group improved the stability, and 2,2,2-trifluoroethyl (Tfe) group was most effective among four substituents tested. Tfe-Pocam group could be used in solid-phase peptide synthesis and peptide condensation reactions, and it was also useful for regioselective disulfide formation reactions.     

Fuzzy space periodic symmetries for polyynes and their cyano-compounds

In our previous papers on the molecular fuzzy symmetry, we analyzed the basic characterization in connection with the fuzzy point group symmetry. In this paper, polyynes and their cyano-derivatives are chosen as a prototype of linear molecules to probe the one-dimensional fuzzy space group of parallel translation. It is notable that the space group is an infinite group whereas the point group is a finite group. For the fuzzy point group, we focus on considering the fuzzy characterization introduced due to the difference of atomic types in the monomer through point symmetry transformation in the beginning; and then we consider the difference between the infinity of space group and the finite size of real molecules. The difference between the point group and the space group lies in the translation symmetry transformation. This is the theme of this work. Starting with a simple case, we will only analyze the one-dimensional translation transformation and space fuzzy inversion symmetry transformation in this paper. The theory of the space group is often used in solid state physics; and some of its conclusions will be referred to. More complicated fuzzy space groups will be discussed in our future papers.     

Odd-even effects in the thermotropic and optical properties of three series of chiral twin liquid crystals

Three series of novel chiral twin liquid crystals consisting of a cholesteryl and a 4'-cyanobiphenyl-4-yloxy group (III) or a 4-cyanophenoxy group (IV) and of a dihydro-cholesteryl and a 4'-cyanobiphenyl-4-yloxy group (V) connected by an alkanoate spacer with a varying number (1-7 and 10) of methylene units were synthesized and their mesogenic properties investigated. Strong odd-even effects were observed as a function of spacer length for the phase transition temperatures, the corresponding entropy changes and the selective reflection wavelengths associated with the chiral nematic phase. The compounds with an even number of methylene units have a smaller pitch than the compounds with an odd number of methylene units. Replacement of the cholesteryl group by a dihydrocholesteryl group results in an larger pitch, whereas replacement of the 4'-cyanobiphenyl-4-yloxy group by a 4-cyanophenoxy group gives a smaller pitch.     

Crystal Structure and Spectra Characters of 2-Benzoly-3-(4-(1,2,4-triazole)-5-anilino-thiophene and 2-(4-Methyl-benzoly)-3-(4- chlrolphenyl)-3-(1,2,4-triazole)-5-anilino-thiophene

Triazole derivatives are widely studied, because they represent the largest group of modern fungicides and are widely used both in human and veterinary therapy and in agriculture. We synthesized the title compound in which the thiophene ring was substituted by a 1,2,4-triazole group, a phenacyl group, a phenylaminol group and a benzene ring.     

Effect of connectivity and terminal functionality on mesophase behaviour of thermotropic liquid crystals containing biphenyl units

A series of 4,4'-disubstituted biphenyls, designated as series HBC, in which, one substituent is an ester group linked directly to the ring and the other is the hydroxy-containing group O(CH₂)_nOH, have been prepared and analysed by differential scanning Calorimetry, polarizing optical microscopy and X-ray diffraction. The introduction of a trimethylene unit between the ester functional group and the biphenyl moiety of the HBC series gives rise to the HBB series, which did not exhibit liquid crystalline behaviour. Interestingly, mesophase behaviour could be restored by replacing the methylene group (of the trimethylene unit) that was directly attached to the biphenyl ring by a keto group (HBOB series). When the terminal hydroxy group of these three series was substituted by a group such as acetoxy or hydrogen, the transition temperatures were reduced, and the disappearance of mesophase behaviour was observed in some cases. However, this could be recovered by the replacement of the ester group by a carboxylic acid group.     

The effect of the bridge group on the thermal stability of nitro-substituted aromatic polyamides

The effect of introducing a bridge group into the diamine moiety on the thermal stability of aromatic polyamides substituted with nitro group in the diamine ring at the ortho position to the amide group was studied. Our present work showed that the bridge group, whether it was electron withdrawing or releasing, did not have a significant effect on the activity of the nitro group for the intramolecular cyclization reaction to poly(benzoxazole)s.     

A new bifunctional coupling agent: synthesis and model reactions

The preparation of a new bifunctional coupling agent with one oxazoline group and one oxazinone group has been described. Model reactions with dodecanoic acid, benzoic acid, n‐dodecyl alcohol and n‐dodecylamine in melt evidenced that both carboxylic acids react selectively with the oxazoline group whereas the oxazinone group is exclusively attacked by the amino and the hydroxy compound, respectively. In blends of amino group terminated polyethers with a carboxy group containing polyethylene the new coupling agent has proven very effective.     

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.     

Are electrophilicity and electrofugality related concepts? A density functional theory study

It is proposed that the electrofugality of a fragment within a molecule is determined by its group nucleophilicity. The variation of electrofugality should be tightly related to the electron releasing ability of the substituent attached to the electrofuge moiety. This contribution closes the set of relationships between philicity and fugality quantities: while nucleofugality appears related to the group electrophilicity of the leaving group, electrofugality is related to the group nucleophilicity of the permanent group.