Catalytic cross-coupling reaction of esters with organoboron compounds and decarbonylative reduction of esters with HCOONH4: a new route to acyl transition metal complexes through the cleavage of acyl-oxygen bonds in esters

The Ru3(CO)12-catalyed cross-coupling reaction of esters with organoboron compounds leading to ketones is described. A wide variety of functional groups can be tolerated under the reaction conditions. Aromatic boronates function as a coupling partner to give aryl ketones. Acyl-alkyl coupling to dialkyl ketones is also achieved by the use of 9-alkyl-9-BBN in place of boronates. The Ru3(CO)12-catalyzed decarbonylative reduction of esters with ammonium formate (HCOONH4) leading to hydrocarbons is also described. No expected aldehydes are produced, and controlled experiments indicate that aldehydes are not intermediate for the transformation. A hydrosilane can also be used as a reducing reagent in place of HCOONH4. A wide variety of functional groups are compatible for both reactions. The key step for both catalytic reactions is the directing group-promoted cleavage of an acyl carbon-oxygen bond in esters, leading to the generation of acyl transition metal alkoxo complexes.     

Ozone-water 1:1 complexes O3-H2O: an ab initio study

Ab initio MO calculations have been carried out for the ozone-water 1:1 complexes in order to elucidate the structures and electronic state of the complexes. The QCISD calculations indicated that three structures are obtained as stable forms of O(3)-H(2)O. The most stable structure of O(3)-H(2)O has C(s) symmetry where the central oxygen of O(3) and all atoms of H(2)O are located on the molecular C(s) plane. The dipole of H(2)O orients toward the central oxygen atom of O(3) (i.e., dipole orientation form). The other two forms are cis and trans forms of O(3)-H(2)O where all atoms are located on the molecular plane, and a hydrogen of H(2)O binds to one of the terminal oxygen atoms of O(3) by a hydrogen bond. The binding energies of O(3) to H(2)O for dipole, cis, and trans forms are calculated to be 2.39, 2.27, and 2.30 kcal/mol, respectively, at the QCISD(T)/6-311++G(3df,3pd)//QCISD/6-311++G((d,p) level. The dipole orientation form is more stable in energy than the cis and trans forms. Rotational constants for the dipole orientation form are calculated to be A = 11.897, B = 4.177, and C = 3.318 GHz which are in good agreement with the experimental values (A = 11.961, B = 4.174, and C = 3.265 GHz). The electronic states of O(3)-H(2)O were discussed on the basis of theoretical results.     

Catalytic synthesis of thiobutyrolactones via CO insertion into the C-S bond of thietanes in the presence of a heterodinuclear organoplatinum-cobalt complex

Heterodinuclear organoplatinum-cobalt complex having a 1,2-bis(diphenylphosphino)ethane ligand (dppe)MePt-Co(CO)4 catalyzes CO insertion into the C-S bond of thietanes in THF at 100 degrees C under 1.0 MPa of CO for 2 h to give gamma-thiobutyrolactone in quantitative yield.     

Palladium-catalyzed bissilylation of arynes with cyclic disilanes: synthesis of benzo-annulated disilacarbocycles

Arynes, generated in situ from 2-(trimethylsilyl)aryl triflate and a fluoride ion, were found to insert into a silicon-silicon bond of cyclic disilanes in the presence of a catalytic amount of a palladium-tert-alkyl isocyanide complex to afford diverse benzo-annulated disilacarbocycles straightforwardly in modest to high yields.     

Synthesis and ring-opening polymerization of novel bicyclic oxalactams: 2-oxa-5-azabicyclo[2.2.2]octan-6-one

A novel bicyclic oxalactam 2-oxa-5-azabicyclo [2.2.21 octan-6-one (2,5-BOL) was synthesized from sodium 3,4-dihydro-2H-pyran-2-carboxylate through a seven-step reaction sequence. Anionic ring-opening polymerization of 2,5-BOL was carried out in bulk at 12OOC or in dimethyl sulfoxide at 40, 60, and 80°C by using potassium pyrrolidonate and the N-benzoyl derivative of 2,5-BOL as catalyst and activator, respectively. The polymerization gave a new polyamide containing cis- and trans-2,5-linked tetrahydropyran rings in the main chain. The cis/trans ratio varied from 70/30 to 95 /5 depending on the reaction conditions. The polyamide having number average molecular weights of 3000–8000 was soluble in a variety of solvents including methanol, ethanol, dimethyl sulfoxide, dimethylformamide, chloroform, and dichloromethane. It began to decompose at 280–32OOC depending on the compositions of the cis- and trans-2,5-linked structural units. The anionic ring-opening polymerizability of 2,5-BOL was found to be much lower than its structural isomer, 8-oxa-6-azabicyclo[ 3.2.11 octan-7-one (8,6-BOL).     

A construction method of certain matrices required in the multivariate heteroscedastic method

Summary For statistical inference about several normal means, the heteroscedastic method was proposed by Dudewicz and Bishop (1979,Optimizing Methods in Statistics, Academic Press, 183–203). However, the practical application in the multivariate case was not possible because it had not been known how to construct the certain matrices required in the method. In this paper, a construction method of the matrices is given.     

Maximum likelihood estimation of Hawkes' self-exciting point processes

Summary A maximum likelihood estimation procedure of Hawkes' self-exciting point process model is proposed with explicit presentations of the log-likelihood of the model and its gradient and Hessian. A simulation method of the process is also presented. Some numerical results are given. The Institute of Statistical Mathematics     

Measurement of polarized target asymmetry on γn→π−p around the second resonance region

The polarized target asymmetry for γn→π^?p was measured over the second resonance region from 0.55 to 0.9 GeV at pion c.m. angles between 60° and 120°. A double-arm spectrometer was used with a deuterated butanol target to detect both the pion and the proton, thus considerably improving the data quality. Including the new data in the amplitude analysis, the radiative decay widths of three resonances were determined more accurately than before. The results are compared with various quark models.