Phenyl tributylstannyl selenide as a promising reagent for introduction [corrected] of the phenylseleno group

A new synthetic method of organoselenium compounds has been developed. When phenyl tributylstannyl selenide (PhSeSnBu(3)) was allowed to react with acyl or aroyl chlorides in the presence of a catalytic amount of a palladium complex such as Pd(PPh(3))(4), Se-phenyl selenol esters were obtained in moderate to good yields. Similarly, the palladium complex catalyzed the reaction of PhSeSnBu(3) with alpha-halo carbonyl compounds to afford the corresponding alpha-phenyseleno carbonyl compounds in moderate yields.     

Improved Synthesis of Aliphatic Ketones by the Reaction of Alkylmercuric Bromides With Nickel Carbonyl in the Presence of Potassium Iodide

An improved and convenient procedure for symmetrical aliphatic ketone synthesis is described, which employs the reaction of alkylmercuric bromides with nickel carbonyl in the presence of potassium iodide.     

Trichiol and 3-epitrichiol acetate, novel cytotoxic sterols with an unprecedented 2,6-dioxabicyclo[2.2.2]octan-3-one ring system from the myxomycete Trichia favoginea var. persimilis

Trichiol (1) and 3-epitrichiol acetate (2), two new sterols, have been isolated from field-collected fruit bodies of the myxomycete, Trichia favoginea var. persimilis, and their structures elucidated by spectral data. Trichiol (1) and 3-epitrichiol acetate (2) possess an unprecedented 2,6-dioxabicyclo[2.2.2]octan-3-one ring system. Trichiol (1) was cytotoxic against HeLa cells, while compound 2 proved to exhibit reversal effect against TNF-related apoptosis inducing ligand (TRAIL)-resistant Jurkat cell lines.     

A clue to elusive macrocycles: unusually facile, spontaneous polymerization of a hexagonal diethynylbenzene macrocycle

[structures: see text] A hexagonal diethynylbenzene macrocycle having exterior octyloxymethyl groups undergoes spontaneous polymerization at room temperature to form hardly soluble materials, in contrast to the corresponding dehydrotetramer and dehydrooctamer, which are stable enough to show their melting points at higher than 140 degrees C.     

Novel synthesis of bridged phenylthienylethenes and dithienylethenes via Pd-catalyzed double-cyclization reactions of diarylhexadienynes

[reaction: see text] Bridged phenylthienylethenes and dithienylethenes were synthesized via Pd-catalyzed double-cyclization reactions of (Z,Z)-1,6-diaryl-1,5-hexadien-3-ynes. Pd-catalyzed as well as photoinduced Z/E isomerization of the products were also investigated.     

High resolution adsorption isotherms of N2 and Ar for nonporous silicas and MFI zeolites

The high resolution adsorption isotherms of N₂ (77.4 K) and Ar (87.3 K) have been measured for two nonporous silicas with different silanol contents (3.3 and 0.35 OH/nm²) and for two MFI zeolite with different Al contents (Si/Al=12.5 and 500). Silanol groups and Al sites (acid sites) gives the significant effect on the N₂ isotherms at submonolayer, but the Ar isotherms are independent of silanols and Al sites. The Ar isotherms, therefore, are preferable in calculation of microporosity of zeolites. The N₂ and Ar isotherms for MFI zeolite (Si/Al=500) have been measured at temperatures of 77–94 K, from which the differential adsorption energies of N₂ and Ar are calculated. The interaction of N₂ with channel surface of MFI zeolite is greater than that of Ar in the range of α _s =0.1–0.7. The hystereses are detected for the N₂ isotherm in p/p ^o=0.1–0.3 at 77.4 K and for the Ar isotherm in p/p ^o=3×10⁻⁴–2×10⁻³ at 87.3 K. However, it is difficult to explain the hysteresis phenomenon using differential adsorption energy.     

Hydrosilylation of carbonyl compounds using a PhSeSiMe(3)/Bu(3)SnH/AIBN system

[reaction: see text] When carbonyl compounds were allowed to react with phenyl trimethylsilyl selenide and tributylstannyl hydride in the presence of a catalytic amount of AIBN as a radical initiator, the hydrosilylation of the carbonyl compounds efficiently proceeded to give the corresponding silyl ethers in moderate to good yields.     

Reactivity of Carbenes and Related Compounds towards Molecular Nitrogen

The thermal N₂ exchange of a number of ¹⁵N-labelled diazo compounds was studied in solution. The compounds involved were 3-diazo-1-methylindolin-2-one ( 1 ), 9-diazofluorene ( 2 ), 5-diazo-1,3-cyclopentadiene-1,2,3,4-tetracarbonitrile ( 3 ), 2-diazo-2H-imidazole-4,5-dicarbonitrile ( 4 ), 4-diazocyclohexa-2,5-dienone ( 5 ), and the conjugate acids of 4 and 5 , namely 4,5-dicyano-1H-imidazole-2-diazonium ion ( 6 ) and 4-hydroxybenzenediazonium ion ( 7 ). Only 1 , 4 , 6 , and 7 exchange their diazo group with ‘external’ molecular N₂. The results are explained on the hypothesis that only organic species which have an empty σ orbital and which are effective in π electron back-donation are able to react with N₂. Thus, reaction with carbenes is likely to occur only if the carbene is in the ¹A₂ singlet state and if its electrophilicity is high.