Triterpene Glycosides of Astragalus and Their Genins. LXI. Occurrence of Cycloartane 6-O-Monodesmosides

Cyclosiversigenin 6-O--L-rhamnopyranoside and 6-O--D-glucopyranoside were isolated fromAstragalus coluteocarpusBoiss. (Leguminosae) andAstragalus dissectusB. Fedtsch. et N. Ivanova, respectively. Cyclosiversigenin 5-O--L-rhamnopyranoside was shown to be an artifact forAstragalus coluteocarpus.Thus, the cyclosiversigenin 6-O--D-glucopyranoside that was isolated from certainAstragalusspecies is hypothesized also to be an artifact. Glycosylation of the 6 -hydroxyl group of cycloartanes by D-glucose and D-xylose, in contrast with other substituents, does not change the low-field position of the PMR signal of the 4-CH ₃ group (1.65 2.01 ppm) that is caused by the influence of deuteropyridine directly on the 6 -hydroxyl. Obviously one of the hydroxyls of the -D-glucopyranoside or -D-xylopyranoside residues has the same effect in this instance.     

Oxidative cyclisation of chalcones with thallium(III)nitrate: Synthesis of (Z)-2-phenylmethylene-7-nitro-3(2H)-benzofuranones

Oxidation of 2-hydroxy-3-nitrochalcones with thallium(III) nitrate gives (Z)-2-phenylmethylene-7-nitrobenzofuran-3(2H)-one derivatives, rather than the more usual 1,2-diaryl-3,3-dimethoxypropan-1-ones or the corresponding isoflavones.

---

Oxydative Cyclisierung von Chalconen mit Thallium(III)nitrat: Synthese von (Z)-2-Phenylmethylen-7-nitro-3(2H)-benzofuranonen (Kurze Mitteilung)

Zusammenfassung Die Oxidation von 2-Hydroxy-3-nitrochalconen mit Thallium(III)nitrat ergab (Z)-2-Phenylmethylen-7-nitro-3(2H)-benzofuranon-Derivate und nicht die üblichen 1,2-Diaryl-3,3-dimethoxypropan-1-one bzw. die entsprechenden Isoflavone.

     

13-甲氧基-6-羟基钩勿烷-5,8,11,13-四烯-7-酮的首次全合成

以α-环柠檬醛(2)为A环合成子,以间甲氧基苄基氯(3)为C环合成子,经缩合及分子内环化反应得关键中间体6.经1H NMR测试发现化合物6为全顺式结构.化合物6经氧化得双羰基化合物7.将7用t-BuOK/t-BuOH处理后得到烯醇式结构的化合物8.最后将异丙基通过Fride1-Crafts反应一步引入得到目标产物1.     

1-Chloro-2,6-dinitro-4-perfluoroalkylthiobenzenes in the Synthesis of Heterocycles

1-Chloro-2,6-dinitro-4-perfluoroalkylthiobenzenes was obtained in first time by perfluoroalkylation of bis(4-chloro-3,5-dinitrophenyl)disulfide in the presence of xenon bisperfluoroalkylcarboxylates. At the interaction of these compounds with potassium ethylxanthogenate only substitution of chlorine atom occurred. The reaction with sodium N,N-dimethyldithiocarbamate leads to the nucleophilic substitution of nitro group with formation of 1,3-benzodithiol-2-one, but on action of ethyl thioglycolate the intramolecular condensation occurs with formation of benzothiazoles N-oxides.     

Synthesis of Substituted 1,2,4-Triazines Based on 1,2-Bis(2,5-dimethyl-3-thienyl)ethanedione

A novel, convenient method has been developed for the synthesis of 1,2-bis(2,5-dimethyl-3-thienyl)ethanedione, from which were prepared 5,6-bis(2,5-dimethyl-3-thienyl)-1,2,4-triazines (analogs of the photochromic 1,2-diarylethenes). The principial possibility of using 1,2,4-triazines obtained as photochromic agents was investigated.     

3-(2-Pyridyl)coumarins

3-(2-Pyridyl)coumarins were prepared by reaction of substituted salicylaldehydes and 2-pyridylacetonitrile. Benzylation, acylation, and aminomethylation of 7-hydroxy-3-(2-pyridyl)coumarin was studied. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 428–431, September–October, 2005.     

Identifying ligand-binding specificity of the oligopeptide receptor OppA from Bifidobacterium longum KACC91563 by structure-based molecular modeling

As a ATP-binding cassette (ABC) transporter the OppA receptor plays key roles in protecting the host organism and transporting nutrients across the intestine by the oligopeptide transporter from symbiotic bacteria and directs maturation of the host immune system. Among lactic acid bacteria, Bifidobacterium longum KACC91563, isolated from fecal samples of healthy Korean neonates, has the capability to alleviate food allergy effects. Operating as a peptide importer, the extracellular OppA receptor from gram-positive B. longum KACC91563 translocates nutrients, specifically peptides, from the outside environment of the intestinal tract to the inside of symbiotic cells. In the present study we attempt to explicate the relationship between the substrate’s specificity from the OppA importer and the probiotic effects of B. longum KACC91563 in the host intestine. It was first identified in this study the specialized structure–function relationship from the OppA importer of B. longum KACC91563 with its structural and functional determinants. This could provide insights into substrate specificity of unique immunological properties and a key switch for the substrate’s metabolism to reprogramming immune responses in the host intestine by structure-based molecular modeling. The probiotic effects of oligopeptide substrate (such as a proline-rich peptide containing at least one branched residue of leucine, isoleucine, and valine) and its metabolism for the OppA from B. longum KACC91563 are attributed to enhancement of the epithelial barrier by several different strain specific pathways to prevent the strong adhesion of pathogens.     

Synthesis of a staurosporine analogue possessing a 7-azaindole unit instead of an indole moiety

The synthesis of a new staurosporine analogue possessing a 7-azaindole unit instead of an indole moiety is described. This synthesis could be achieved by coupling a sugar moiety previously tosylated in 2′ position to the azaindolocarbazole aglycone. Nucleophilic substitution on the carbon bearing the tosyl group yielded to the key cyclization leading to a compound in which the carbohydrate part is linked to both indole and azaindole nitrogens.     

A Review on Anode Side Interface Stability Micromechanisms and Engineering for Garnet Electrolyte-based Solid-state Batteries

Li-ion solid electrolytes, which are compatible with metallic lithium anodes, are the key component of all solid-state batteries. Recently, the garnet Li₇La₃Zr₂O₁₂ solid electrolyte has experienced booming development and shown great potential for its excellent overall performance. However, further understanding of its stability with lithium is required for a longer battery lifetime. In this review, latest research work on the interface between garnet-type solid electrolytes and lithium is presented, including both mechanisms governing interface stability and interface engineering methods. The development prospects and potential directions for following research are also discussed in the last section.     

一氧化碳在高温超导体型的Ba2-xSrxYCu3O7-a上的催化氧化

用粉末XRD法、EXAFS法,激光喇曼散射法、热重法和高真空质谱TPD法研究了超导体型氧化还原催化剂Ba_(2-x)Sr_xYCu_3O_(7-α)(x=0,0.25, 0.50, 0.75, 1.00)的物理化学性质, 并用常压连续流动法测定了它们的CO催化氧化活性, 得到了催化剂氧化反应活性大小与催化剂的可失氧量(即晶胞中O_I 位置上的氧量)之间存在着线性关系的结论.