Synthesis and X-ray structures of new cycloalka[e]pyrano[2,3-b]pyridine derivatives: novel tacrine analogues

A new series of tacrine (9-amino-1,2,3,4-tetrahydroacridine) analogues consisting of a cycloalka[e]pyrano[2,3-b]pyridine linked to a quinolyl ring has been synthesized. These compounds were prepared from the appropriately substituted pyran derivative via a Friedländer reaction with selected cycloalkanones in high yields. Single crystal X-ray structures are reported for four compounds.     

First‐Principles Study on Doping of SnSe2 Monolayers

Doping is a vitally important technique that can be used to modulate the properties of two‐dimensional materials. In this work, by using first‐principles density functional calculations, we investigated the electrical properties of SnSe₂ monolayers by p‐type/n‐type and isoelectronic doping. Substitution at Sn/Se sites was found to be easy if the monolayer was grown under Sn‐/Se‐poor conditions. Substitutions at Sn sites with metallic atoms (e.g. Ga, Ge, In, Bi, Sb, Pb) resulted in positive substitution energies, which indicated that they were not effective doping candidates. For substitutions at Se sites with nonmetallic atoms, no promising candidates were found for p‐type doping (e.g., N, P, As). Among these, N and As showed positive substitution energies. Although P had a negative substitution energy under Sn‐rich conditions, it introduced trap states within the band gap. For n‐type doping (e.g., F, Cl, Br), all the calculated substitution energies were negative under both Sn‐ and Se‐rich conditions. Br was proven to be a promising candidate, because the impurity introduced a shallow donor level. Finally, for isoelectronic doping (e.g., O, S, Te), the intrinsic semiconducting features of the SnSe₂ monolayer did not change, and the contribution from the impurity to the states near the band edge increased with the atomic number.     

QSAR and mode of action studies of insecticidal ecdysone agonists†

A series of our SAR and QSAR studies of synthetic moulting hormone agonists, dibenzoylhydrazines (DBH), exhibiting insecticidal/larvicidal activity are reviewed in this article. We prepared a number of analogues where various substituents are introduced into the two benzene rings of DBH and measured their biological activity using various biological systems. Larvicidal activity was against larvae of the rice stem borer Chilo suppressalis and the moulting hormone activity was in terms of the stimulation of N-acetylglucosamine incorporation in a cultured integument system of the same insect species. Binding affinity to the ecdysone receptor was assayed with intact Sf-9 cell lines in which the ADME processes are negligible as well as using receptor proteins obtained by in vitro translation of the responsible cDNA cloned from cell-free preparation of integumentary tissue of C. suppressalis. Variations in the biological activity indices were either correlated between two types of activity or correlated using physicochemical molecular and substituent parameters in terms of the classical QSAR. Comparisons among correlations and with recently revealed X-ray crystallographic findings clearly indicate the physicochemical meaning of parameters significant in the correlation equations to help understanding molecular mechanism of the moulting hormonal action.     

Synthesis of Neoglycolipid Analogues of the Oligosaccharide Portion of Ganglioside GM3

In order to elucidate the molecular specificity of the antimelanoma response induce by GM3 included in proteoliposome preparation, we designed syntheses of a series of neoglycolipids containing the trisaccharide portion of GM3 or its fragment. In the present paper, we synthesized two neoglicolipids containing as a lipid, a racemic glycerol unit substituted by two aliphatic octadecyl ether chains. The di‐ and trisaccharide derivatives were prepared as glycosides of the spacer by a sequence of isopropilidenation‐benzylation‐hydrolysis followed by sialylation. The condensation between the oligosaccharides and the lipid was performed by an amidation reaction.     

Efficient Synthesis of New Nucleoside Analogues with a Methylenecyclobutane Unit

Synthesis of eight nucleoside analogues 4–11 with a methylenecyclobutane unit is described. Wittig reaction with 2‐hydroxymethylcyclobutanone 12 gave a mixture of Z (13) and E (14) derivatives, which was separated before functional modifications. The heterocyclic moieties were introduced via a Mitsunobu reaction either on the saturated chain or on the unsaturated chain. When adenine was used in this reaction, only the N‐9 substitution products were obtained. Removal of the protecting groups provided the target products.     

Synthesis of a novel Boc-protected cyclopropane-modified proline analogue

The synthesis of the Boc derivative of a novel member of the cyclopropane-modified proline library, Boc-protected 5-azaspiro[2.4]heptane-6-carboxylic acid, is reported. The synthesis was performed in six steps starting from (2S,4R)-4-hydroxyproline using a modified Simmons-Smith reaction as the key step. The reaction conditions for all the steps were carefully selected to avoid racemization at the chiral centers in the intermediates and the final product.     

含有二糖结构的核苷类似物的合成

利用Ferrier重排反应合成了两个系列的连有核音的2,3-不饱和糖苷(其中核耷包括尿苷、腺苷、肌苷等).这些新化合物的结构通过NMR和MS(HRFAB)得到证实.     

Synthesis,characterization and cytotoxic investigations of novel bis(indole) analogues besides antimicrobial study

Two series of novel bis(indole) analogues viz., N′-((5-substituted-1H-indol-3-yl)methylene)-n-(1H-indol-3-yl)alkanehydrazides (7a–f) and N′-((5-substituted-1-(3-methylbut-2-enyl)-1H-indol-3-yl)methylene)-n-(1H-indol-3-yl)acetohydrazide (8a–f) were synthesized and characterized by spectral analysis. The target molecules were screened for their antimicrobial, anticancer activities and structure and activity relationship (SAR) was investigated. Compounds 7a, 7c and 8a were found to be active in antimicrobial screening. Anticancer screening reveals that Compound 7c was active against HeLa cell line with an IC₅₀ of 43.1 μM and compound 7d was found to be interesting candidate with an IC₅₀ of 26.0 and 30.2 μM against Colo-205 and Hep G2 cell lines respectively.     

A Switch in the Hydrophobic/Hydrophilic Gas-Adsorption Character of Prussian Blue Analogues: An Affinity Control for Smart Gas Sorption

Porous coordination polymers are molecule-based materials presenting a high degree of tunability, which offer many advantages for targeted applications over conventional inorganic materials. This work demonstrates that the hydrophilic/hydrophobic character of Prussian blue analogues having a lipophilic feature may be tuned to optimize the gas adsorption properties. The role of the coordinatively unsaturated metal sites is emphasized through a combination of theoretical and experimental study of water, ethanol, and n-hexane adsorption.