Asymmetric Synthesis of （S）-Dimethyl -4, 4＇-dimethoxy-5, 6, 5＇, 6＇-dimethenedioxybiphenyl-2, 2＇-dicarboxylate

(S)-Dimethyl-4, 4‘-dimethoxy-5, 6, 5‘, 6‘-dimethenedioxy-biphenyl-2, 2‘-dicarbonylate was synthesized in reasonable yield through a series of reactions, including chiral oxazolinemediated asymmetric Ullmann coupling, from methyl 2-bromo-5-methoxy-3, 4-methenedioxybenzoate.     

Über das hexahydrophenthiazin, 2. Mitt.

Zusammenfassung Neben der früher beschriebenen Modifikation des Hexahydrophenthiazins vom Schmp. 101° wurde eine zweite Modifikation vom Schmp. 110–112° aufgefunden. Es werden die sterischen Verhältnisse diskutiert. Als zusätzlicher Konstitutionsbeweis wurde die hydrierende Desulfurierung mitRaney-Nickel herangezogen, bei der allerdings in Äthanol als Lösungsmittel N-Alkylierungen eintreten. Für die als Nebenprodukt gefundene Verbindung C₁₈H₁₈N₂S₂ wurde eine Konstitutionsformel vorgeschlagen.Mit 3 Abbildungen     

Über das Zirkoniumsilicid ZrSi2 und das Titansilicid TiSi2

Zusammenfassung Durch Reduktion eines Gemisches von Zirkonkaliumfluorid und Kaliumfluorsilikat mittels Aluminium bei zirka 1200° erhält man ein Zirkonsilicid ZrSi₂ kristallisierend in rhombischen Säulchen.Das gleiche Silicid bildet sich, wenn man auf aluminothermischem Wege Zirkonoxyd in Gegenwart von Quarzsand und Schwefel mittels Aluminiumgries reduziert.Erhitzt man ein Gemenge von Zirkonkaliumfluorid und Aluminium durch längere Zeit auf 1200°, so entsteht eine in quadratischen Blättchen kristallisierende Zirkoniumaluminiumlegierung von der Zusammensetzung ZrAl₃.Nach demselben aluminothermischen Verfahren, das zur Darstellung des Zirkoniumsilicides geführt hat, kann man ein Titansilicid gewinnen, das der Formel TiSi₂ entspricht und das in tetragonalen Pyramiden kristallisiert.     

SYNTHESIS AND EVALUATION OF A NEW PHOTOSTABILIZER—2, 2, 6, 6-TETRAMETHYL-4-PIPERIDINYL SALICYLATE FOR POLYMERS

A new photostabilizer--2,2,6,6-tetramethyl-4-piperidinylsalicylate (TMPS) has been syn-thesized by ester-exchange reaction between 2,2, 6, 6-tetramethyl-4-piperidinol and methylsalicylate.The photostabilizing effect of TMPS and Tinuvin 770, PDS on the photodegradation of cis-1,4-polybutadiene has been investigated for comparison. The results observed show that the mosteffective stabilizer of the three is TMPS. The reason of the good photostabilizing effect of TMPSwas discussed by fluorescence spectra.     

FTIR spectra of the 2ν4, ν4 + ν6 and 2ν6 bands of formaldehyde

High resolution IR spectra of the overtones and the combination band of the ν₄ and ν₆ modes of formaldehyde (2ν₄, ν₄ + ν₆ and 2ν₆) were measured in the region of 2200–2650 cm⁻¹ using FTIR. The combination band ν₄ + ν₆, whose dipole transition is forbidden from molecular symmetry, was observed due to the intensity borrowed from the other bands. The observed frequencies were analysed by a Hamiltonian in which A-type Coriolis interactions and Darling—Dennison interaction were taken into account. The ratio and the relative signs of the transition dipole moments of the overtone bands, μ_2ν4 and μ_2ν6, have been determined by analysing the intensity distribution of the vibration—rotation lines.     

Über das 2-Dichlormethyl-oxazolin und seine Kondensation mit 4-Nitrobenzaldehyd

Zusammenfassung N-Dichloracetyläthanolamin (I) wurde über das mit SOCl₂ erhaltene N-Dichloracetyl--chloräthylamin (II) durch Alkali in das 2-Dichlormethyl-oxazolin (III) übergeführt, dessen sehr leicht erfolgende hydrolytische Umwandlungen beschrieben werden. Kondensation von 4-Nitrobenzaldehyd mit (III) erfolgt ohne jedweden Katalysatorzusatz unter den mildesten. Bedingungen an der überaus reaktiven Methingruppe des Dichlormethylrestes von (III) zu 2-[-(4-Nitrophenyl)--oxy-, -dichloräthyl]-oxazolin (VI), dessen Konstitution an Hand eines O-Acetats und durch die saure Hydrolyse zu einer -(4-Nitrophenyl)-, -dichlorhydracrylsäure und Äthanolamin bewiesen wird.Herrn Prof. Dr.L. Ebert zum 60. Geburtstag gewidmet.     

STUDIES ON STEREOSELECTIVE SYNTHESIS OF 4R,6R,4-ACETOXY-6-PENTYLVALEROLACTONE

The title compound has been synthesized from the chiralbuilding block 2 through five steps.     

Synthesis,spectroscopic, structural and thermal characterizations of [(C7H6NO4)2TeBr6·4H2O]

Tellurium (IV) complexes with pyridine-2,6-dicarboxylate ligand were synthesized by slow evaporation from aqueous solutions yielding a new compound: [(C₇H₆NO₄)₂TeBr₆·4H₂O]. The structure of this compound was solved and refined by single-crystal X-ray diffraction. The compound is centrosymmetric P2₁/c (N°: 14) with the parameters a = 8.875(5) Å, b = 15.174(5) Å, c = 10.199(5) Å, β = 94.271° (5) and Z = 2. The structure consists of isolated H₂O, isolated [TeBr₆]^2? octahedral anions and (pyridine-2,6-dicarboxylate) [C₇H₆NO₄]⁺ cations. The stability of the structure was ensured by ionic and hydrogen bonding contacts (N–H?Br and O–H?Br) and Van-Der Walls interaction. The thermal decomposition of the compound was studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The FTIR and Raman spectroscopy at different temperatures confirm the existence of vibrational modes that correspond to the organic, inorganic and water molecular groups. Additionally, the UV–Vis diffuse reflectance spectrum was recorded in order to investigate the band gap nature. The measurements show that this compound exhibits a semiconducting behavior with an optical band gap of 2.66 eV.     

2, 3, 4, 5, 6-五苯基苯甲醛的新合成途径

从四苯基环戊二烯酮与乙二醇缩肉桂醛通过干法在260-270℃直接加成并脱CO,接着经氧化、水解制备了2,3,4,5,6-五苯基苯甲醛,对目标产物的结构进行了^1HNMR,IR,UV-Vis和元素分析表征。在对反应中间产物进行分离、鉴定的基础上提出了该反应的可能途径。     

Syntheses, 95Mo NMR Spectroscopy and Structures of Distorted Cubic Mo4(��3-O)4(��2-O2P(CH2C6H5)2)4O4 and the Open Mixed-Valent Cluster, Mo4(��3-O)2(��2-O2P(CH2C6H5)2)6O6

The reaction of MoO₂(acac)₂ and dibenzylphosphinic acid in ethanol leads to a red distorted cubic tetrameric cluster, Mo₄(??³-O)₄(??²-O₂P(CH₂C₆H₅)₂)₄O₄, and a pink open mixed-valent cluster, Mo₄(??³-O)₂(??²-O₂P(CH₂C₆H₅)₂)₆O₆, when the reduction is carried out at 120 and 75 °C, respectively. ⁹⁵Mo NMR spectroscopy revealed a singlet for Mo₄(??³-O)₄(??²-O₂P(CH₂C₆H₅)₂)₄O₄ (1) at 584.9 ppm (????_1/2 = 4500 Hz) and two resonances for Mo₄(??³-O)₂(??²-O₂P(CH₂C₆H₅)₂)₆O₆ (2) at 238.8 ppm (????_1/2 = 1250 Hz) and 6.4 ppm (????_1/2 = 5999 Hz), which were assigned to the Mo(V) and Mo(VI) sites, respectively. DFT geometries and ⁹⁵Mo DFT-GIAO chemical shifts for Mo₄(??³-O)₄(??²-O₂P(CH₃)₂)₄O₄ (3) and Mo₄(??³-O)₂(??²-O₂P(CH₃)₂)₆O₆ (4) are consistent with X-ray crystallography and ⁹⁵Mo NMR of 1 and 2. The open complex, Mo₄(??³-O)₂(??²-O₂P(CH₂C₆H₅)₂)₆O₆·2(CH₂Cl₂), exhibits a central Mo(V)?CMo(V) single bond at 2.6217(5) Å with each Mo(V) atom bonded to one oxo (trans-disposed) terminal ligand.     

Synthesis of 3 or 4-Substituted Pyridine-2, 6-Dicarboxylic Acid

Time-resolvedcircularlypolarizedluminescence(CPL)studieshavebeenparticularlysuccessfulatmeasuringdifferencesinquenchingrateconstantsincertaindiastereomericdonor-acceptorsystems'ItisanticipatedthatthesetypesofexperimentsmaybeappliedtomorecomplexsystemsinvolvingracemiclanthanideemittercomplexesinasolutioncontainingtransitionmetalcomplexesenantioselectivelyboundtoDNA2.However,theluminophoreswereonlyconfinedtoLn(DPA),'-andLn(CDA),'(Ln=Eu' ,Tb' ,DPA=dipicolinatedianion,CDA=chelidamate).Eff…     

Über das Kriechen kristallisierender Salze, 2. Mitt.

Zusammenfassung Versuchsergebnisse über die Verteilung des bivariant gebundenen Wassers und von Wasserstoff- bzw. Hydroxylionen in den Kristallen bei kriechender Kristallisation, wie auch die hydrolytische Spaltung dieser Kristalle, werden dargelegt. Sie zeigen, daß der Gehalt an Wasser und die damit verbundene hydrolytische Spaltung bei den Kristallen in der Kristallkruste größer ist als bei den auf dem Boden des Gefäßes ausgeschiedenen Kristallen. Die Wasserstoff- bzw. Hydroxylionen verteilen sich so, daß, in Zusammenhang mit dem pH-Wert der Ausgangslösung, die Lösungen, bereitet aus den Kristallen der Kristallkruste, einen niedereren bzw. höheren pH-Wert besitzen, als die Lösungen, bereitet aus den Kristallen am Boden des Gefäßes.     

Synthesis and structures of zirconium complexes [Et2H2N]+2[ZrCl6]2–, [Me3NCH2Ph]+2[ZrCl6]2–•MeCN, [Ph3PC6H4(CHPh2-4)]+2[ZrCl6]2–•2 MeCN,and [Ph4Sb]+2[ZrCl6]2–

Russian Chemical Bulletin - The complexes [Et2H2N]+2[ZrCl6]2– (1), [Me3NCH2Ph]+2[ZrCl6]2–?MeCN (2), [Ph3PC6H4(CHPh2-4)]+2[ZrCl6]2–?2 MeCN (3), and...     

Crystal Structure of Loliolide (5, 6,7a-Tetrahydro-6-hydroxy-4, 4, 7a-trimethyl-2 (4H)-benzofuranones)

1INTRODUCTIONThetitlecompound,C,,H,,O,(mp:146～148'C),forthefirsttime,wasiso-latedfromClinopodiumpolycephalum(Vant-)byC.Y.WuetHsuancalled"DuanXueliu"inChinesethatisusedinfolkmedicineforthetreatmentofhaemorrhagiadisease[1i.Itsstructurehasalreadybeendeterminedt2ibymeansofUV,lR,NMRandchemicalsynthesis.Sinceloliolideappearedtohaveantitumoractivity"'andim-munosuppressiveactivity'#'inrecentyears,weaffirmedthestructurebyX-raydiffractionanalysis.2EXPERIMENTALApaleyellowtransparentcry…     

A Rapid and Efficient Synthesis of 2, 4, 6-Triarylpyridines under Microwave Irradiation

An rapid and efficient synthesis of 2, 4, 6-triarylpyridines is reported using substituted benzaldehydes, substituted acetophenones and ammonia as starting materials under microwave irradiation in the presence of PEG-400.     

Preparation and Electrochemical Properties of 3-Pyridinyl-6-aryl-1, 2, 4-triazolo [3, 4-b][1, 3, 4]thiadiazoles

A series of 3-pyridinyl-6-aryl-1, 2, 4-triazolo[3, 4-b][1, 3, 4]thiadiazoles(PATT) were prepared, the structures were confirmed by 1R and ^1H NMR spectra. The results of cyclic voltammetry measurements imply that all these compounds have a higher electron affinity (EA) than 2-(4-biphenyl)-5-(4-tert-butyl phenyl)-1, 3. 4-oxadiazole (PBD) which implies that PATT could be acting as better electron acceptors than widely used electron transporting material PBD.     

Synthesis of an Optically Active Trisubstituted α,β-Butenolide, (S)-4, 6-Dihydroxy-2, 3-dimethyl-2-hexesoic Acid 1, 4-Lactone,from 2-Deoxy-D-ribose

The title compound has been synthesized efficiently from 2-deoxy-D-ribose. The synthesis involves : 1) an aldol like carbon-carbcr. bond formation of (S)-3, 5-dibenzyioxy-2-pentanor.e (8) with a lithium enolate of methyl propanoate, and 2) O-de-benzylation of the aldol adducts (11) for a γ-lactonization followed by β-elimination of the desired butenolide skeleton.     

The Synthesis of 2, 4, 6-Triisopropyl-1, 3, 5-trioxane Catalyzed by Ionic Liquids

The synthesis of 2, 4, 6-triisopropyl- 1, 3, 5-trioxane with high yield and desirable selectivity from solvent-free cyclotrimerization of isobutyraldehyde catalyzed by ionic liquids was reported in this work.