A Green and Efficient Synthesis of Xanthenedione Derivatives Promoted by InCl_3·4H_2O in Ionic Liquid

Xanthenedione derivatives have held considerable interests in recent years, since theyconstitute a structural unit in a number of natural products1 and have been used asversatile synthons because of the inherent reactivity of the inbuilt pyran ring2. Usually,poly-hydrogenated xanthenediones (3, Scheme 1) can be obtained through the acid orbase catalyzed condensation of appropriate active methylene carbonyl compounds withaldehydes. But this method is not very satisfactory because of the prolong…     

First Application of Optically Active trans-1,2-Bis(2- aminophenyl)cyclopentane for Asymmetric Reaction: Enantioselective N-Acetylation of Secondary Alkyl Amines

Optically active amines are essential constituents or building blocks for the synthesis of many medicines. Efficient resolution of racemic amines through enzymatic or nonenzymatic methods plays an important role in the production of chiral amines1. The kinetic resolution of amines through nonenzymatic acetylation catalysts has been the focus of our interest. For this purpose, we have developed the first enantioselective N-acetylation reagent 1 (Figure 1), which was derived from 1,1'-binaphthy…     

Synthesis and Crystal Structure of aNovel Polymer Copper（ Ⅱ） Complex

1 INTRODUCTION One-dimensional coordination polymers of metal complexes have been extensively studied for many years owing to their unusual properties, and many efforts have been made to prepare these kinds of complexes. Study on these polymer complexes has an active field of coordination chemistry in recent years[1～5]. In this study we obtained a com- plex C14H9CuNO3CH3OH, of which the carboxy- late oxygen atom acts as the bridging ligands to coordinate to the second metal atom, fo…     

Stereospecifical Preparation of (E)-a-Stannyl-1-alkenylphosphonates and their Application in Stille Reaction

1-Alkenylphosphonates are very useful compounds for organic transformations1 and for the synthesis of biological active compounds 2. On the other hand, alkenylstannes are of particular synthetic interest and have attracted a great deal of attention in recent years3. For this reason, we anticipate the a-stannyl-1-alkenylphosphonates, a new class of 1, 1- difunctional reagents which combined a-stannyl and phosphonate groups in one molecule, will play an important role in organic synthesis. Th…     

Synthesis of a New β-Mercaptoalcohol

Mercaptoalcohols are a rare class of natural products. Some optically active mercaptoalcohols have been used as catalysts in asymmetric reduction of prochiral Ketone1,2. In this letter, we report the synthesis of a new optically active (-mercaptoalcohols, (R)-1,1-diphenyl-2-mercapto-3-methyl-1-butanol 7, from L- valine.Our first attempt is showed in Scheme 1. According to literature's method L-valine was converted to (S)-2-Hydroxy-3-methylbutanoic acid 21,2. 2 was treated with MeOH/SOCl2…     

Intercalation of PM-19 into and in vitro Release of Anti-tumor Drug from Layered Double Hydroxide

Recently, controlled release ot drugs and gene delivery technology have received considerable attention due to their numerous advantages including prolonged duration of action of an active agent, improved efficacy, reduced toxicity and convenience compared to the conventional dosage forms. In this field typical systems are polymer delivery systems depending on the hydrolysis-induced degradation,     

SYNTHESES AND CRYSTAL STRUCTURES OF (Et_4N)_2(Fe_2Se_2(SPh)_4) AND (Et_4N)_2(Fe_4Se_4Cl_4)

<正> Since the discovery of iron-sulfur proteins , a number of analogous compounds of the active sites of iron-sulfur proteins has been synthesized and characterized . Due to the similarity between sulfur and selenium, some selenoproteins with similar active site as iron-sulfur proteins were found . We have synthesized a series of iron-selenium compounds in correlative study with the iron-sulfur compounds. In this paper, we will discuss the syntheses and crystal stuctures of the title compounds. The spectroscopic properties of these compounds have been under investigation.     

A New Isoprenylated flavonol from the Leaves of Broussonetia kazinoki

Broussonetia kazinoki Sieb (Moraceae) is distributed throughout China and Japan. Previous investigations of this plant revealed the presence of isoprenylated flavans, isoprenylated flavonoids, isoprenylated 1,3-diphenylpropanes1 and alkaloids2,3. Natural prenylated flavonoids have shown potent inhibition against human hepatoma PLC/PRF/5 and epidermoid carcinoma KB cells in vitro4. In order to search for its biologically active compounds, chemical study on this plant was carried out and le…     

SYNTHESIS AND CRYSTAL STRUCTURE OF BIS (TETRAETHYLAMMONIUM) BIS[μ-(l,2-DITHIOETHELENE)-S,S']-BIS[l,2-DITHIOETHELENE-S,S']-DI-IRON(Ⅲ)

<正> INTRODUCTION. In our attempts of chemical simulation of the active center of nitrogenase we have been interested in the reaction system of various ferrous thiolates with thiomolybdatee. In previous papers, we have reported the syntheses of ferrous monodentothiolates and their reactions with tetrathiomolybdate. The possible structure type of ferrous thiolates when bidentothiols are used inspired our interest in this work.     

Studies of Self-assembled Monolayers Formed by Imidazoline on Iron Surface by SEM and SECM

Self-assembled monolayers (SAMs) formed from organic substances can improve the inhibition of metal corrosion, because uniform and closely packed films formed on the metal surface providing an insulating layer1, 2. SAMs on the iron surface are studied so far because iron is one active metal which is easily corroded in the air. In this paper, SECM and SEM have successfully been applied in the study of SAMs inhibition corrosion for iron. SECM has been used to study the electrochemically a…     

Asymmetric Syntheses Aided by Biocatalysts

This article summarizes the achievements of the authors‘ group in the area of biocatalyst-catalyzed organic reactions in recent 10 years. A strain of Geotrichum sp. obtained by screeninu is capable of stereoselectlvely reducing a number of carbonyl compounds. In many cases, the stermghemistry is complementary with that obtained by baker‘ s yeast. Therefore, this microorganism provides a useful pathway to the preparation of alcohol eompounds with specific configurations. On the other hand, a nmmber of plant sourees have been screened for oxynitrilases and the hydrocyanation reactions of various arylcarboxalde-hydes have been investigated.A“micro-aqueous reaction system“ was invented,by which a serles of novel optically active cyanohydrins were prepared.On this hasis,a high through-put comtimasous reaction system has been designed.This paper also deseribes examples of the syntheses of bio-active compounds by using the optieally active compounds obtained from the above mentioned catalytic reactions as precursors.     

EHMO Studies of the Structures and Reactivities of Oxyhemocyanin and Oxytyrosinase Bimiclear Copper Active Sites

We have generated one possible active site structure of Oxyhemocyanin (Oxy-Hc) and two possible active site structures of Oxytyrosinase (Oxy-Ty) using the EHMO method. Oxy-Hc active site has a plane configuration, while Oxy-Ty has boat configuration. When there exist water molecules, two water molecules are connected with the Oxy-Ty active site weakly. Calculations for the reactions of Oxy-Hc and Oxy-Ty (the water-off) with phenol demonstrate that the former reaction is thermodynamically forbidden, while the latter Is realizable.     

Study on Roots of Firmiana plantanifolia (L.f.) Marsili

Firmiana plantanifolia (L.f.) Marsili is a Chinese medicine used in the treatment of numerous disorders such as rheumatism, asthma, fracture, and tumor etc.[1] In the course of a search for biological active compounds from medicinal plants,[2] we have examined the water extract of the root of this plant and succeeded in isolating three novel constituents named firmianones A, B and C (Scheme 1), along with 9 known compounds. Their UV, HRMS and NMR spectral data indicated that they are isoprenylated naphthoquinone dimmers. Firmianones A and B have a novel hexacyclo [14.8.0.02,7.06.15.099.14.018,23]tetracosa-1(16),3,9(14),10,12,7,19,21,23-nonaen-8-one skeleton and their absolute stereochemistry was determined by CD exciton-coupling experiments.     

A Convenient and Stereospecific Synthesis of (Z)-Benzylidenephthalides

Several 3-benzylidenephthalides have been isolated from natural sources1-2. Some of them are known to possess useful biological activity1 and are also valuable intermediates3 for the synthesis of naturally occurring biologically active compound. Most of the natural 3-benzylidenephthalides exist in the (Z)-configuration. Synthe-tic methods for construction of a 3-benzylidene-phthalide skeleton have been developed4. Some of these methods for synthesizing highly oxygen-functionalized compound…     

Synthesis of a new complex Chromium (Ⅲ) 2-mercaptonicotinate

Chromium is an essential trace element for mammals[1-3].Diabetes is a chronic disease with major health consequence.Studies show that the occurrence of diabetes have great thing to do with the chromium deficient。Almost 40 years after the first report of glucose tolerance factor(GTF) [4] no conclusive evidence for an isolable ,biologically active form of chromium exited。Three materials have been proposed to be the biologically active form of chromium:“glucose tolerance factor”,chromium Pi…     

A New Monodisperse Reactive Resin with Active Groups on the Particle Surface

The cross-linked polymer beads with reactive groups as active supports have been widely used in many fields such as chromatographic separation, solid phase synthesis, catalytic reaction, ion exchange and adsorption etc. In resent years, the synthesis and application of monodisperse polymer beads with different structures have been rapidly developed1~4. It is obvious that this type of monosized resin as matrix of active supports will be even more advantageous in some applications. This paper pr…     

Synthesis, Crystal Structure and Antibacterial Activity of 1-（（2-Chloroquinolin-3-yl）-methyl）-pyridin-2（1H）-one

On the basis of the interesting structures and biological activities exhibited by several heterocyclic systems possessing the pyridone nucleus such as mappcine and camptothecin, we have planed to design the synthesis, crystal studies and antibacterial activity of the new 1-((2- chloroquinolin-3yl)-methyl)-pyridine-2(1H)-one building block. An X-ray analysis has provided valuable insight into the effect of steric factors on the three-dimensional shape of this compound which serves as a useful advanced intermediate in the synthesis of these biologically active molecules. A multistep synthesis of camptothecin (5) has been designed by retrosynthetic analysis as part of an ongoing program on lead anticancer drug.     

Alkaloids from Stems of Ervatamia yunnanensis (II)

The non-alkaloid chemical constituents, which were isolated from the stems of Ervatamia yunnanensis Tsiang (Apocynaceae), have been reported in previous paper 1. As a part of our continuing research on the isolation of active compounds for anti-addictive …     

Attempt to Resolute Chiral Clusters by Optically Active Hydrazide

Due to the framework chirality optically active clusters can provide the proof that a cluster as a whole, and not one of its fragments, acts as a catalyst, most of the work have been directed to the synthesis of tetrahedron-type chiral clusters1-3. However, there remains another major problem to obtain the pure enantiomers. Although Vahrenkamp had obtained some pioneering results in this area before 19901, only several racemic chiral clusters have been separated into pure enantiomers until now…     

NAD~ ANALOGS IN FORMATION OF NEW FLUOROPHORES ON ULTRAVIOLET IRRADIATION WITH D-GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE

A number of NAD~ analogs have been tested in their ability to form fluorescent deriva-tives when UV irradiated with the active site Cys-149 carboxymethylated GAPDH and this hasbeen compared with their properties of acting as hydrogen acceptors and forming the Rackerband. Among the analogs tested, NHD~ , NGD~ , APAD~ and ∈NAD~ give positive results inall the above-mentioned reactions whereas αNAD~ , NMN~ and CPAD~ are all negative.FPAD~ forms a fluorescent derivative on UV irradiation with the carboxymethylated enzymebut is inactive as a hydrogon aceeptor and does not form the Racker band. This is probablydue to thiohemiacetal formation of the pyridine 3-aldehyde of this derivative with the activesite SH group required for both the latter 2 reactions. TPAD~ , although active as a hydrogenacceptor, does not form either a fluorescent derivative or a Racker band. The fact that forthe great majority of the analogs, the property of forming fluorescent derivatives is is parallelwith their hydrogen acceptor activity seems to show that the formation of the fluorescentderivative is indeed at the active site, and hence can be used as an intrinsic probe for thestudy of the conformation of the active site of this enzyme.