Development of 125Te synchrotron-radiation-based Mössbauer spectroscopy

The Mössbauer spectra of the 35.49 keV excited state of ¹²⁵Te were observed in the energy domain using synchrotron radiation for the first time. The obtained isomer shifts and Debye temperature agree with previous experiments. These results show that this method will be applicable to various compounds.     

A facile method for the synthesis of polycyclic indole derivatives: the generation and reaction of tungsten-containing azomethine ylides

Treatment of N-(o-alkynylphenyl)imine derivatives with W(CO)(5)(L) induces the 5-endo-mode of cyclization of the imine nitrogen onto the electrophilically activated alkyne moiety to afford a novel reactive species, a metal-containing azomethine ylide. [3 + 2] cycloaddition of this ylide species with various electron-rich alkenes proceeds smoothly to give unstable carbene complexes, which in turn undergo 1,2-hydrogen-, alkyl-, and aryl-migration to afford in good yield 6-5-5 tricyclic indole skeletons having an alkyl or an aryl substituent at the 3-position of the indole nucleus.     

Synthesis of Highly Functionalized gamma-Butyrolactones from Activated Carbonyl Compounds and Dimethyl Acetylenedicarboxylate

A triphenylphosphine-catalyzed cyclization of alpha-keto esters, alpha-keto nitriles, or alpha,alpha,alpha-trifluoroacetophenone with dimethyl acetylenedicarboxylate is reported to produce highly functionalized alpha,beta-unsaturated gamma-butyrolactones in moderate yields. Thus treating a mixture of methyl 4-nitrophenylglyoxylate and dimethyl acetylenedicarboxylate with 20 mol % of triphenylphosphine afforded 5,5'-disubstituted 3-methoxy-4-(methoxycarbonyl)-2(3H)-furanone in 94% yield. In the reaction of alpha-keto esters R(1)COCOOMe, an electron-withdrawing R(1) substituent is required for satisfactory reactivity. On the other hand, electron-donating R(1) substituents give higher yields with alpha-keto nitriles R(1)COCN. Another electron-deficient carbonyl compound, alpha,alpha,alpha-trifluoroacetophenone, gave the corresponding lactone in good yield. The use of an alpha-hydroxy ketone as an electrophilic carbonyl compound with more than 1 equiv of triphenylphosphine produced dihydrofuran derivatives. One equivalent of triphenylphosphine oxide was obtained as a major product. An intramolecular Wittig reaction is proposed as a reaction mechanism.     

Electrophilic Cyanation of Boron Enolates: Efficient Access to Various β‐Ketonitrile Derivatives

The highly efficient electrophilic cyanation of boron enolates using readily available cyanating reagents, N‐cyano‐N‐phenyl‐p‐toluenesulfonamide (NCTS) and p‐toluenesulfonyl cyanide (TsCN), is reported. Various β‐ketonitriles were prepared by this new protocol, which has a remarkably broad substrate scope compared to existing methods. The present method also allowed efficient synthesis of β‐ketonitriles containing a quaternary α‐carbon center. In addition, a preliminary result with the use of a chiral boron enolate for the enantioselective cyanation reaction is described.     

Mobilities of polyatomic molecular ions in He gas

The mobilities of polyatomic molecular ions in He gas, measured at 83 and 306 K using a low-temperature drift tube, were smaller than the polarization limit K _pol. The mobilities of atomic or small molecular ions tended to show a bump at intermediate reduced field, and then approach the polarization limit at low reduced field; however, the measured mobilities of polyatomic molecular ions were different. We compared the experimental mobilities with values calculated using the MOBCAL program, and found that they agreed well.     

Mononuclear cobalt (III) complexes with <Emphasis Type="Italic">N</Emphasis>-salicylidene-2-hydroxy-5-bromobenzylamine and <Emphasis Type="Italic">N</Emphasis>-salicylidene-2-hydroxy-5-chlorobenzylamine

Cobalt (III) complexes with N-salicylidene-2-hydroxy-5-bromobenzylamine (H₂sbba) and N-salicylidene-2-hydroxy-5-chlorobenzylamine (H₂scba), [n-(C₄H₉)₄N][Co(sbba)₂] (I) and [n-(C₄H₉)₄N][Co(scba)₂] (II), were synthesized. The crystal structure of II was determined by the single-crystal X-ray diffraction method at 90 K confirming its crystallization in the monoclinic space group P2₁/n with a = 11.729(2) Å, b = 16.901(3) Å, c = 21.483(4) Å, β = 98.840(4)°, V = 4208.2(14) ų, D_x = 1.295 g cm^?3, and Z = 4. The R1 [I > 2σ(I)] and wR2 (all data) values of 0.0664 and 0.1920, respectively, for all 9521 independent reflections. The compound is composed of a tetra(n-butyl)ammonium cation and an octahedral cobalt(III) complex anion with two scba^2? ligands in a meridional fashion. The electronic spectral features of I and II are consistent with the octahedral cobalt(III) ion with an N₂O₄ donor set.