Chemical studies on the anobiidae: Sex pheromone of the drugstore beetle, stegobium paniceum (L.) (coleoptera)

Chemical an spectroscopic evidence is presented to show that 2,3-dihydro-2,3,5-trimethyl-6-(1-methyl-2-oxobutyl)-4H-pyran-4-one (10) is the sex pheromone produced by the female drugstore beetle, Stegobium paniceum L.     

Direct Electrochemistry of Multi‐Copper Oxidases at Carbon Nanotubes Noncovalently Functionalized with Cellulose Derivatives

This study describes the direct electron transfer of multi‐copper oxidases, i.e., laccase (from Trametes versicolor) and bilirubin oxidase (BOD, from Myrothecium verrucaria) at multiwalled carbon nanotubes (MWNTs) noncovalently functionalized with biopolymers of cellulose derivatives, i.e., hydroxyethyl cellulose (HEC), methyl cellulose (MC), and carboxymethyl cellulose (CMC). The functionalization of the MWNTs with the cellulose derivatives is found to substantially solubilize the MWNTs into aqueous media and to avoid their aggregation on electrode surface. Under anaerobic conditions, the redox properties of laccase and BOD are difficult to be defined with cyclic voltammetry at either laccase/MWNT‐modified or BOD/MWNT‐modified electrodes. The direct electron transfer properties of laccase and BOD are thus studied in terms of the bioelectrocatalytic activities of the laccase/MWNT‐modified and BOD/MWNT‐modified electrodes toward the reduction of oxygen and found to be facilitated at the functionalized MWNTs. The possible application of the laccase‐catalyzed O₂ reduction at the laccase/MWNT‐modified electrode is illustrated by constructing a CNT‐based ascorbate/O₂ biofuel cell with the MWNT‐modified electrode as the anode for the oxidation of ascorbate biofuel.     

Die Reaktion von SeCl4 mit Übergangsmetalltetrachloriden. Synthese und Kristallstrukturen von (SeCl3)2MCl6 mit M = Zr,Hf, Mo,Re

The Reaction of SeCl₄ with Transition Metal Tetrachlorides. Synthesis and Crystal Structures of (SeCl₃)₂MCl₆ with M = Zr, Hf, Mo, Re The transition metal tetrachlorides ZrCl₄, HfCl₄ and MoCl₄ react with SeCl₄ in closed ampoules at temperatures of 140°C to (SeCl₃)₂MCl₆ (M = Zr, Hf, Mo) which are all isotypic and crystallize in the (SeCl₃)₂ReCl₆ structure type (orthorhombic, Fdd2, Z = 8, lattice constants for M = Zr: a = 1165.7(1)pm, b = 1287.2(2)pm, c = 2180.2(2)pm; for M = Hf: a = 1162.9(2)pm, b = 1285.0(2)pm, c = 2178.2(3)pm; for M = Mo: a = 1153.8(1)pm, b = 1267.7(1)pm, c = 2147.4(2)pm). The Cl^? ions form a hexagonal closest packing with one fourth of the octahedral holes filled by Se⁴⁺ and M⁴⁺ in an ordered way. The MCl₆ octahedra are regular, the SeCl₆ octahedra are distorted with 3 short and 3 long Se? Cl bonds (mean 215 pm and 287 pm). The structures can thus be regarded as built of SeCl₃⁺ and MCl₆^2? ions. Magnetic susceptibility measurements show for M = Zr the expected diamagnetic behavior, for M = Mo and Re paramagnetic behavior according to the Curie-Weiss law with magnetic moments of 2.5 B. M. for M = Mo and 3.7 B. M. for M = Re corresponding to 2 and 3 unpaired electrons respectivly.     

Effect of conformational control of chiral oxazaborolidine by π-π stacking interaction of a pentafluorophenyl group toward asymmetric borane reduction

A pentafluorophenyl group can act as a stereo-controlling group in oxazaborolidine-catalyzed asymmetric borane reduction through intramolecular π-π stacking interaction with a phenyl group. The intramolecular π-π interaction in oxazaborolidine bearing pentafluorophenyl group is confirmed by calculations and ¹H NMR study. The interaction affects the enantioselectivity of the asymmetric reduction of acetophenone while the extent is small.     

Transformed steroids

A preparative method for 9a-hydroxylation of ⁵-3-hydroxysteroids using the fungi ofCircinella sp. 10Kh-1220 not capable of modifying theA ring has been developed. It is established that the yields of the main and the side products greatly depend on the transformation conditions, mycelium age, and the structure of the steroid substrate. Under the optimal transformation conditions novel 9-hydroxysubstituted derivatives of androstenolone, pregnenolone, 16-dehydro-16,17-epoxy-, and-16-methoxypregnenolone have been obtained in 36–80 % yields.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 737–743, April, 1994.     

Dispersion state of CuO on CeO2

XRD and XPS are used to study the dispersion state of CuO on ceria surface. The dispersion capacity values of CuO measured by the two methods are consistent, which are of 1.20 mmol CuO/100 m² CeO₂. In addition, the results reveal that highly dispersed Cu²⁺ ions are formed at low CuO loadings and that increasing the CuO content to a value higher than its dispersion capacity produces crystalline CuO after the surface vacant sites on CeO₂ are filled. The atomic composition of the outermost layer of the CuO/CeO₂ samples has been probed by using static secondary ion mass spectroscopy (SSIMS), and the ratim of Cu/Ce are found to be 0.93 and 0.46 for the 1.22 and 0.61 mmol CuO/CeO₂ samples respectively. Temperature-programmed reduction (TPR) profile with two reduction peaks at 156 and 165°C suggests that the reduction of highly dispersed Cu²⁺ ions consists of two steps and is easier than that of CuO crystallites, in which the TPR profile has only one reduction peak at about 249°C. The above experimental results are in good agreement with the prediction of the incorporation model. Project supported by the National Natural Science Foundation of China.     

4-Hydroxy-2-quinolones. 122. 1-Hydroxy-3-oxo-5,6-dihydro-3H-pyrrolo[3,2,1-<Emphasis Type="Italic">ij</Emphasis>]-quinoline-2-carboxylic acid hetarylamides as potential antitubercular agents

An improved method is reported for the synthesis of a series of 1-hydroxy-3-oxo-5,6-dihydro-3H-pyrrolo[3,2,1-ij]quinoline-2-carboxylic acid hetarylamides. The antitubercular activity of all of the compounds prepared has been studied. The structure-biological activity dependence revealed is discussed. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1023–1033, July, 2007.     

Beiträge zur Chemie des Phosphors. 221 [1]. Stannylsubstituierte Bicyclo [1.1.0]tetraphosphane: Bildung und Eigenschaften von R3Sn(H)P4 (R  CH3, C6H5, c-C6H11, o-C7H7)

Contributions to the Chemistry of Phosphorus. 221. Stannyl-Substituted Bicyclo[1.1.0]tetraphosphanes: Formation and properties of R₃Sn(H)P₄ (R ? CH₃, C₆H₅, c-C₆H₁₁, o-C₇H₇) The unsymmetrically substituted bicyclo[1.1.0]tetraphosphanes Me₃Sn(H)P₄ ( 1 ), Ph₃Sn(H)P₄ ( 2 ), (c-Hex)₃Sn(H)P₄ ( 3 ) and (o-Tol)₃Sn(H)P₄ ( 4 ) have been obtained by reaction of a solution of (Na/K) HP₄ with R₃ SnCl (R ? Me, Ph, c-Hex, o-Tol) under proper conditions. The structure of the compounds 1 – 4 , which are only stable in solution, has been elucidated by means of ³¹P-NMR-spectroscopy. Whereas 3 exists at ?60°C as the exo,endo isomer, 1, 2 and 4 are fluctuating molecules at room temperature and probably invert between the three possible configurational isomers (exo,exo-, exo,endo- and endo,endo-form).     

Deoxypegan-1-one derivatives. synthesis and borohydride reduction of 3-[(E)-arylmethylidene]-3,9-dihydropyrrolo[2,1-b]quinazolin-1(2H)-ones

3-[(E)-Arylmethylidene]-3,9-dihydropyrrolo[2,1-b]quinazolin-1(2H)-ones were prepared by reaction of quinazolyl-2-propionic acid hydrochloride with aromatic aldehydes in acetic anhydride in the presence of Et₃N. 3-[(E)-Arylmethylidene]-1,2,3,9-tetrahydropyrrolo[2,1-b]quinazolin-1-ols were formed by reduction of the 3-arylidene derivatives with sodium borohydride in methanol, readily lost water when heated with acids, and were converted into 3-[(E)-arylmethylidene]-3,9-dihydropyrrolo[2,1-b]quinazolines. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 463–467, September–October, 2006.     

On the affinity of cytosine towards electrophiles

Ab initio SCF computations on the intrinsic preferences of the H⁺, CH ₃ ⁺ and C₂H ₅ ⁺ cations towards the two principal sites of protonation or alkylation on cytosine, N₃ or O₂, show that this preference undergoes a continuous modification with the increase in size and complexity of the cation. N₃ is the preferred site of fixation of H⁺, O₂ the preferred site of C₂H ₅ ⁺ , while CH ₃ ⁺ has no marked preference. The exchange repulsion term of the binding energy appears responsible for the preference of C₂H ₅ ⁺ for O₂.This work was supported by the Ligue Francaise contre le Cancer and the National Foundation for Cancer Research (USA)