First Total Synthesis of an Analogue of (±)-Hypargenin B

Hypargenin B, a diterpene with the abietane skeleton, was isolated by Ayhan from the root of an endemic species salvia hypargenia and showed antibacterial activity1. In this diterpene, the junction of A/B ring is trans. In order to provide for studying further the relationship between the structure and bioactivities, we develop a novel route whereby the hypargenin B methyl ether 22 could be obtained in good yield. To our knowledge no total synthetic work has been reported on the title com…     

Study on the Interaction between Distamycin Analogs and DNA from Herring Sperm by Fluorimetry

Distamycin is a naturally occurring antibiotic which binds to the AT rich regions in minor groove of DNA1. We have reported the interaction between the analogs and calf thymus DNA by circular dichroism spectropolarimetry (CD) and isothermal titration calorimetry (ITC)2. Due to the greater sensitivity of fluorescence-based techniques in comparison with CD, we employ the fluorimety to explore the interaction between four new distamycin analogs and DNA from herring sperm. O2NNNOHNNO…     

Synthesis of (1H)-3,4-Dihydropyrrolo[2,1-c][1,4]oxazin-1-one Derivatives

It has been found that some acyl derivatives of 1,2,3,4-tetrahydro-1-indolizin-1-one 1and (1H)-3,4-dihydropyrrolo[1,2-a]pyrazin-1-one 2 show remarkable anti-inflammatory and analgesic activities1,2. The interest in extending the study of structure-activity relationships and search of new potent anti-inflammatory and analgesic agents led us to design and synthesize (1H)-3,4-dihydropyrrolo[2,1-c][1,4]oxazin-1-one 3 derivatives. NO 1 NNHO2 87654321ONO3 A few examples of the p…     

Preliminary Study on Pyrolysis of Polymethylsilsesquioxane by FT—IR and XPS

The term polysilsesquioxanes in this paper refers to all structures with the empiri-cal formulas (RSiO3/2)n where R is hydrogen or any alkyl, alkylene, aryl, arylene, or organo-functional derivatives of alkyl, alkylene, or aryl. Polymethylsilsesquioxane (PMSQ) is characterized by its low weight loss at high temperatures. X-ray photoelectron spectroscopy (XPS) characterization of PMSQ was unavailable from reported literatures. In this study, the pyrolysis was carried out in an inert at…     

Biotransformation of 14-Deacetoxy-13-oxo sinenxan A by Ginkgo Cell Cultures

Sinenxan A, 2a, 5a, 10b,14b-tetraacetoxy-4(20),11-taxadiene, is a taxoid isolated from the callus cultures of Taxus spp. in high yield (ca. 1~2% of dry weight)1,2. The rich resources and its taxane-skeleton vest it valuable potential for the semisynthesis of paclitaxel or other structurally related bioactive compounds, such as 搒econd -generation?taxoid anticancer agents and taxane-based multidrug resistant anticancer agents3-5. Many remarkable studies on its structural modification by chemi…     

Diastereoselective α-Alkylation of β-Amino Esters: Preparation of Novel α-Substituted β-Amino Esters from α-Amino Acids

b-Amino acids and their derivatives have attracted considerable attention in recent years due to their occurrence in biologically active natural products, such as dolastatins 11, cyclohexylnorstatine 22 and taxol 33. bAmino acids also find application in the synthesis of blactams4, piperidines5, indolizidines6. Moreover, the peptides consisting of bamino acids, the so called bpeptides, have been extensively studied recently7. Consequently, considerable efforts have been directed to the synt…     

Studies on the Catalytic Properties of Magnesia Supported on γ-Alumina

ＩｎｔｒｏｄｕｃｔｉｏｎＧｌｙｃｏｌｅｔｈｅｒｓａｒｅｉｍｐｏｒｔａｎｔｉｎｄｕｓｔｒｉａｌｄｅｒｉｖａｔｉｖｅｓｏｆｅｐｏｘｉｄｅｓ .Ｐｏｌｙｅｔｈｙｌｅｎｅ ｇｌｙｃｏｌｅｔｈｙｌｅｔｈｅｒｓａｎｄｐｏｌｙｐｒｏｐｙｌｅｎｅｇｌｙｃｏｌｅｔｈｙｌｅｔｈｅｒｓａｒｅｔｗｏｉｍｐｏｒｔａｎｔｓｅｒｉｅｓｏｆｐｒｏｄｕｃｔｓ .Ｇｌｙｃｏｌｅｔｈｅｒｓａｒｅｇｏｏｄｓｏｌｖｅｎｔｓｄｕｅｔｏｔｈｅｐｒｅｓｅｎｃｅｏｆ—Ｏ—ａｎｄ—ＯＨ ｇｒｏｕｐｓ.Ａｓａｒｅ ｓｕｌｔ ,ｔｈｅｙａｒｅｗｉｄｅｌｙｕｓｅ…     

Selective Deoxygenation of Nitrones Mediated by Sm/CoCl_26H_2O Reductive System

Aldimines are an important class compounds1 which can be prepared by selective deoxygenation of nitrones. Thus more attention was paid to the selective deoxygenation of nitrones in organic synthesis. The reducing reagents, include low-valent titanium2, acetic formic anhydride3, sodium hydrogen telluride4, tributyltin hydride4, terathiomolybdate5, metallic indium in aqueous media6, zinc-aluminum trichloride7, aluminum iodide8, triphenylphosphine9, etc. However, there are various limitations …     

Mild Hydrothermal Synthesis and Optical Properties of the Complex Fluoride KMgF_3 Doped with Eu

Perovskite complex fluorides have attracted great interests due to their particular physical properties such as antiferromagnetic characteristics1, photoluminescence behavior2. Complex fluorides are usually prepared by solid state reactions at high-temperature. In spite of inert atmosphere, it is inevitable to contain a bit of oxygen. This has great effect on the luminescent character of rare earth ions. There are also reports about synthesizing some binary fluorides by high-temperature hy…     

Two New Dammarane Glycosides from the Acid Hydrolysis Product of Panax Notoginseng

In our continuing research works on Panax notoginseng (Burk.) F. H. Chen, a famous traditional Chinese herb medicine1, two new dammarane glycosides named notoginsenosides T1 (1) and T2 (2) were isolated from the mild acid hydrolysis products of the root saponins. We report herein the structure elucidation of these two novel glycosides.Notoginsenosides T1(1) was obtained as white solid, [(] = +14.49 (0.50, MeOH). Its negative mode HR-FAB-MS spectrum showing the quasimolecular ion peak a…