Synthesis and Crystal Structure of a Hexameric Organooxotin Cluster from Benzilic Acid

1 INTRODUCTION There is great interest in the study of organotin carboxylic ester compounds due to their consider- able biological activities and structural diversities[1~3]. Since Holmes, R. R.[4] first reported the hexameric drum organotin compound, many organotin carboxy- lic ester compounds with drum-shape have been syn- thesized in recent years[5, 6]. It has been revealed that organotin compounds containing carboxylate ligands with additional donor atoms that are available for coord…     

Synthesis and Structural Characterization of [(C_2H_5)_4N][V~((V))O_2(OC_6H_3(OCH_3)CHNNCSNH_2)]·H_2O

1 INTRODUCTIONAlthough vanadium plays an increasingly recognized role as a biometal[1~4], little is known about the structure and function of vanadium compounds in living organisms. A classical and nevertheless rapidly developing field of application for oxovanadates and related compounds is their use as catalysts in polymerization and oxidation reactions[5,6], and recent interest has focused on oxovanadates as model compounds for the interaction of oxovanadates with the active sites of en…     

Syntheses and Structural Researches of Yb~(3+) Complexes with Nitrilotriacetic Acids──Nine-coordinate K_3[Yb(nta)_2(H_2O)]·5H_2O and Eight-coordinate Na_3[Yb(nta)_2]·6H_2O Complexes

IntroductionBecause the rare earth metal compounds havethe promotion to the growth of animals andplants[1] ,and the functions of antiinflammation,antibacterium[2 ] ,anticoagulantion[3 ] and anti-caner[4] ,the investigation on the syntheses and bio-logical activities of the rare earth metal compoundshas attracted many chemists attention.The com-pounds of heavy rare earth element Yb are consid-ered as the representative of these rare earth metalcompounds.Otherwise,the radioactive rare earthmetal…     

Syntheses and Crystal Structures of Bis-[oxo-bis(p-ferrocenylbenzoxy di-n-propyltin)](I) and Bis[oxo-bis(β-ferrocenoylpropionyloxy di-n-propyltin )](II)

1 INTRODUCTION The studies of organotin compounds are of current interest owing to their wide range of applications such as biocides and thermal stabilizers for PVC plastic etc. Besides, the pharmaceutical properties such as the antitumor activities of organotin carboxylates have been investigated[1, 2]. In recent years, reports of synthesis and structural elucidation of various organotin carboxylic esters have appeared, revealing various new structural possibilities[3]. Since Kealy an…     

THE ATTACHMENTS OF PHYCOBILINS TO CYSTEINYL RESIDUES

The attachments of phycobilins to cysteinyl residues have been worked out through the reactions of phycoerytbrobilin dimethyl ester and phycocyanobilin dimethyl ester with cysteine methyl ester and reduced glutathione dimethyl ester respectively. A series of model compounds which carry the same conjugative skeletons as the chromophores in phycobillproteins have been purified anti identified. These compounds are characterized with strong fluorescence emission and circular dichroism effects which appeared weaker for the common bilinoid chromophores. Analyses of the circular dichroism effects of these compounds indicated that the major reaction products of phycobilins with cysteine methyl ester and reduced glutathione dimethyl ester carried the same stereochemical configuration as the chromophores in phvcobilinoroteins     

A simple,efficient and green procedure for Michael addition catalyzed by [C_4dabco]OH ionic liquid

A dabco-based basic ionic liquid,1-butyl-4-aza-1-azaniabicyclo[2.2.2]octane hydroxide,has been developed as a catalyst for a convenient and rapid method for the Michael addition of active methylene compounds to a b-unsaturated carboxylic esters and nitriles.The method is very simple,and the yields are very high.The catalyst can be recycled several times without much loss of activity.     

Study on Ionic Organotin Compounds Ⅲ. Synthesis of Five-Coordinated Anionic Tin(Ⅳ) Complexes and Crystal Structure of [ ( i-Pr)2NH2] [ PhSn(μ2-SCH2COO)2]

The study of ionic organotin compounds is of current attention owing to their diversified molecular structures and wide range of applications, such as biological activities[1 ～3] and as catalysts in organic synthesis. [4] Recently, we synthesized some new ionic organotin compounds by dephenylation reaction. [5] In this paper, we continued to study the reaction of mercaptoacetic acid with phenyltin trichloride in the presence of organic base. The reaction equation was as follows:     

Synthesis, Crystal Structure and Electrochemical Properties of Complex [Ni(2,2’-bipy)_2(ClC_6H_4COO)(H_2O)](ClO_4)

1 INTRODUCTION Nickel is vital for organism as a trace element and it often acts as component or secondary factor of enzyme. In the latest two decades, biological inor- ganic chemistry of nickel has become one of the hottest fields and the coordination chemistry of nic- kel has made a great progress[1]. Complexes built upon organic aromatic carboxylic acid and metallic ion have attracted chemists’ interest for years due to their potential applications in material, medicine, molecular ele…     

Preparation and Characterization of a Novel Benzimidazolium Bronsted Acid Ionic Liquid and Its Application in the Synthesis of Arylic Esters

A novel Brφnsted acid task specific ionic liquid 1-ethylbenzimidazolium tetrafluoroborate （[Hebim]BF4） with functional benzimidazolium cation was synthesized and characterized by ^1H NMR, IR, MS spectra and elemental analysis. This novel ionic liquid was successfully used as dual solvent-catalyst for the synthesis of arylic esters. Higher yields were obtained in the presence of [Hebim]BF4 in comparison with other imidazolium ionic liquids because of the good solubility of the aromatic alcohols and aromatic carboxylic acids in [Hebim]BF4. The product could be separated conveniently from the reaction system, and the ionic liquid could be easily reused after removal of water under vacuum. After 10 times reuse, the selectivity of the ester was still 100%.     

Synthesis and Crystal Structure of Na_(10)[LaSiW_(11)O_(39)(H_2O)_4]_2·22H_2O

1 INTRODUCTION The pseudoliquid character of heteropoly compounds as catalysts is determined by their crystallographic properties. Study on the crystal structures of the heteropoly compounds could provide interesting information to enrich heteropoly acid and catalytic chemistry[1]. In the past, Zhuo Ying-Li抯 group has synthesized the carbamidine salts of 1:1 LnL(Ln=lanthanide, L=[SiW11O39]n－)[2], and Pope抯 group has reported that -SiW11O39 units are connected by lanthanide catio…     

Synthesis,Spectroscopic Properties and Crystal Structural Characterization of a Triphenyltin(IV) Complex with 5-Bromonicotinic Acid

1 INTRODUCTION Organotin esters of carboxylic acids are widely used as biocides, fungicides and homogeneous ca- talysts in industry[1～3]. Recently, pharmaceutical pro- perties of organotin esters of carboxylic acids have been investigated for their antitumour activity[4, 5]. Studies on organotin compounds containing car- boxylate ligands with additional donor atoms (e.g. N, O or S) that are available for coordination to the tin atom have revealed that new structural types may lead to di…     

POLAR SUBSTITUENT EFFECTS OF ORGANOPHOSPHORUS ESTERS IN STRUCTURE-REACTIVITY STUDIES

In order to study the polar substituent effect almost with no steric effect in organophosphoruschemistry,a series of 4-substituted-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane 1-oxides(1)and p-substitutedphenylphosphonates(2)and corresponding mono hexyl esters(3)as model were synthesized.~(31)P-NMR chemicalshifts of compounds(1)in methanol and deuterioacetone were determined.The Δδ values reflect 4-sbstituent po-lar effect.The ~(31)P-NMR of compounds(2)and(3)and the pKa of compounds(3)were also measured.Theresults showed that the trend of polar effects of substituents in both carboxylic and organophosphates chemistryare similar,and the change of polar effects in variation with the alkyl groups is not significant.     

Synthesis of 8-(ω-Chloroalkyl)-dipyrrinones

Dipyrrinones,typically brightyellow compounds with a long axis- polarizedπ- π* excita-tion in the1 4 π- electron- conjugated chromophore,such as xanthobilirubic acid methyl ester(XBRMe) ,are useful building blocks for the syntheses of biologically important tetrapyrrolepigments such as bilirubin(the yellow pigmentof jaundice) [1 ],and they have been extensivelyused as model dipyrrole pigments for the spectroscopic and the photochemical studies of linertetrapyrroles such as bilirubin and bil…     

Synthesis and Crystal Structure of a One-dimensional Infinite Chain Organotin Complex [(n-Bu)_3Sn(OCOC_5H_4NO)]_n

1 INTRODUCTION Organotin esters of carboxylic acid are widely used as biocides and fungicides and as homogeneous cata- lysts in industry[1~3]. In recent years, the pharmaceu- tical properties of carboxylic acid have been investi- gated for the antitumour activity[4~6]. In general, bio- cidcal activities of organotin complexes are greatly influenced by the molecular structures and coordina- tion numbers of the tin atom[7, 8]. It is revealed that organotin complexes containing carboxylate l…     

Syntheses and Crystal Structures of Molybdenum-Sulfur Clusters Mo_3S_4 (dtp)_3(o-CH_3OC_6H_4COO)(Py) and Mo_3S_4 (dtp)_3(p-HOC_6H_4COO)(DMF)·EtOH

1 INTRODUCTION Recent years have seen a drastic increase of compounds containing the Mo3S4 core. A major synthetic route to these compounds is by the reaction of the aqua ion [Mo3S4(H2O)9]4+ with different kinds of ligands replacing some or all of the water molecules. In this way, Mo3S4(dtp)4(H2O), which was synthesized by the spontaneous- assembly method in 1986[1] and its structural characterization and chemical reactivity have been well recognized [2], can be rationally synthesize…     

Aqueous Diels-Alder Reactions of Cyclopentadicnc with Symmetric Diester of Fumarate or Maleate

Cis- or irans- dimethyl and diethyl ester of bicyclo[2,2,1]hept-5-ene-2,3-die(2 or 4) were used as pesticides 1-4 in the fourties and fifties of the century to prevent orkill mosquito, fly and flea. The of's-dimethyl ester Za was also added to cosmetics forthe same purpose 5. The diethyl and dipropyl esters (2b and Zc) could be used to makerubber and elastomers6'7. Besides, this kind of compounds are important intermediatesfor synthesis of some drugs.The Diels-Alder reaction of cyclopentadie…     

Preparation and Reactions of Amino Acid Ester Sulfones as New Remote Asymmetrical Induced Reagents

The development of chiral auxiliary-controlled asymmetric synthesis has been receiving increasing interest in recent yearsfi,2] Various chiral auxiliary reagents have been observed[3] and a lot of results showed that variation of the chiral auxiliary could influence asymmetric induction. Recently, it has been reported the reaction of the aminated sulfones as a remote chiral auxiliary with α,β-unsaturated carbonyl compounds.[4] Here we would like to report the preparation of amino acid ester sulfones as new remote asymmetrical induced reagents and their reactions with α,β-unsaturated esters.     

Theoretical Estimate of Hydride Affinities of Aromatic Carbonyl Compounds

Aromatic carbonyl compounds are one type of the most important organic compounds, and the reductions ofthem by hydride agents such as LiAlH4 or NaBH4 are widely used in organic synthesis. The reactivity of carbonyl compounds generally increases in the following order: ketone ＜ aldehyde, and amide ＜ acid ＜ ester ＜ acid halide, which could be related to their hydride affinities (HA). In the previous paper, Robert[1] calculated the absolute HAof a series of small non-aromatic carbonyl compounds. In this paper, we use DFT method at B3LYP/6-311 + + G (2d, 2p)∥B3LYP/6-31 + G* level to estimate hydride affinities of five groups of aromatic carbonyl compounds. The detailed results are listed in Table 1.     

Synthesis and Structure of a Novel Compound [Cu_2(EDTA)(Py)_2(H_2O)_2]·2H_2O

1 INTRODUCTION Multinuclear coordination compounds have attrac-ted much attention due to their distinctive optical, elec-tric and magnetic properties as well as enzyme ana-logue[1～4]. It is important for carboxylic acid to de-sign this compound[5～8]. EDTA is a useful titrant formetal determination because EDTA molecule is easyto coordinate with a metal atom (1:1). Other types ofEDTA-M compounds are seldom to know except Ln2-M3(EDTA)3(H2O)11?12H2O[5] and (UO2 )2EDTA[9]. …     

Efficient Fixation of Carbon Dioxide by Electrolysis Facile Synthesis of Useful Carboxylic Acids

Electrochemical fixation of atmospheric pressure of carbon dioxide to organic compounds is a useful and attractive method for synthesizing of various carboxylic acids. Electrochemical fixation of carbon dioxide, electrochemical carboxylation, organic halides, organic triflates, alkenes, aromatic compounds, and carbonyl compounds can readily occur in the presence of an atmospheric pressure of carbon dioxide to form the corresponding carboxylic acids with high yields, when a sacrificial anode such as magnesium or aluminum is used in the electrolysis. The electrochemical carboxylation of vinyl bromides was successfully applied for the synthesis of the precursor of nonsteroidal anti-inflammatory agents such as ibuprofen and naproxen. On the other hand, supercritical carbon dioxide （scCO2） has significant potential as an environmentally benign solvent in organic synthesis and it could be used both as a solvent and as a reagent in these electrochemical carboxylations by using a small amount of cosolvent.