Akio Toshimitsu

Phenylselenenyl chloride in acetonitrile-water: a highly convenient reagent for hydroxyselenation of olefins and preparation of cyclic ethers from dienes

Abstract The reaction of phenylselenenyl chloride with olefins in aqueous acetonitrile affords β-hydroxyalkyl phenyl selenides in excellent yields, providing the most convenient method for hydroxyselenation of olefins so far reported. When the reaction was applied to conjugated dienes, monohydroxyselenated products were obtained in good to excellent yields. From non-conjugated dienes, on the other hand, cyclic ethers containing two phenylseleno groups were produced in good to excellent yields, the first step of this reaction being the hydroxyselenation of one double bond.

Electrical characteristics of single-component ambipolar organic field-effect transistors and effects of air exposure on them

We investigated the electrical characteristics of single-component ambipolar organic field-effect transistors (OFETs) by controlling the device structure and preparation and the measurement conditions. Six organic semiconductor materials (copper-phthalocyanine, tris-(8-hydroxyquinoline)aluminum (Alq3), alpha-sexithiophene, 4-4′-bis-styrylphenyl, 2,7-diphenyl[1]benzothieno[3,2-b]benzothiophene, or a photopolymerized polydiacethylene derivative (PDA) were used as the active layer, and all were found to transport both holes and electrons. The PDA-based FETs had the highest hole and electron mobilities (0.12 and 0.025 cm2/V s, respectively). We also investigated the effect of air exposure on the OFETs. The hole mobility was barely affected by the exposure while the electron mobility was significantly affected. The threshold voltage for p-channel operation was shifted by the exposure while that for n-channel operation was not, indicating that the hole density in the active layer is increased by air exposure wh...

Ambipolar light-emitting organic field-effect transistors using a wide-band-gap blue-emitting small molecule

The authors applied a wide-band-gap (2.9eV) molecule of 4,-4′-bis(styryl)biphenyl (BSBP) as an active layer in light-emitting organic field-effect transistors. They found that BSBP provided both relatively high field-effect hole mobility of 0.01cm2∕Vs and photoluminescence efficiency of 20% in thin film. They achieved ambipolar operation by without breaking vacuum through devices’ preparation and measurements, applying aluminum contacts, and inserting a hydroxyl-free poly(methylmethacrylate) layer, and light emission was observed when the device was operated in the ambipolar mode. The results presented here will open the way to fabricating efficient light-emitting transistors with high mobility.

Recent developments in silicon interelement linkage: the case of functionalized silyllithium, silylenoid and sila-ylide*

As one representative family of silicon interelement linkages, functionalized silyl anions and related species such as silylenoids and sila-ylides are described, focusing on the development of new synthetic methodologies and the effects of the heteroatom substituents on the bonding nature and the reactivity of these species.

Selective synthesis of heterocyclic compounds through the intramolecular substitution of phenylselenonyl group by nitrogen or carbonyl oxygen in amides

Abstract Nitrogen heterocycles were produced by the oxidation of N-[ω-(phenylseleno)alkyl]-p-toluenesulfonamides through the intromolecular substitution of the resultant phenylselenonyl group by the nitrogen atom. By the oxidation of the corresponding benzamides, on the other hand, cyclization by nitrogen or carbonyl oxygen proceeded depending on the number of carbon atoms between the nucleophile (amide) and the leaving group (selenonyl group).

Palladium-catalyzed allylic oxidation of olefins by t-butyl hydroperoxide and tellurium(IV) oxide

Abstract Treatment of several cyclic olefins, β-pinene, allylbenzene, and estragole with palladium(II) salt in acetic acid in the presence of t-butyl hydroperoxide and tellurium(IV) oxide afforded mainly the corresponding allylic acetates. The reaction proceeded catalytically with palladium(II) salt, t-BuOOH working as a reoxidizing agent.

Enhanced nucleophilicity of ambiphilic silylene and silylenoid bearing 8-(dimethylamino)-1-naphthyl group

Abstract Some new aspects of intramolecularly amine-coordinated silylenes, ammonium silaylide, and amine-coordinated magnesium (chloro)silylenoids are summarized. The divalent silicon species bearing the 8-(dimethylamino)-1-naphthyl group, generated by the thermal degradation of a pseudo-pentacoordinated ethoxy- or fluoro-disilane, behaves as a nucleophilic ammonium silaylide as well as the amine-coordinated silylene, whose electrophilic character is weakened in comparison with that of free silylenes in some reactions in the presence of trapping agents such as 1,3-diene, diphenyl acetylene (in the absence or presence of water), and phenylacetylene, and in the absence of any trapping agent. The amine-coordinated silylenoid also behaves as an ambiphile, but the reaction courses are different from those observed with the amine-coordinated silylene and silaylide. A novel amino-group migration from naphthyl carbon to silicon has been observed in both species.

Nitration of aromatic hydrocarbons and ipso-nitrosodemetallation of arylmetal compounds in sodium nitrite–trifluoroacetic acid

Treatment of aromatic hydrocarbons with sodium nitrite in trifluoroacetic acid affords nitroarenes in high yields in sharp contrast to a report in which aromatic nitration occurred only slightly in almost the same reaction system. Nitrosodemetallation at the ipso-position occurs to give nitrosoarenes in good yields by similar treatment of various arylmetal compounds (metal = Hg, Tl, Si, Sn, Pb, or Bi), nitrodemetallation hardly occurring in this case. The former reaction proceeds through attack of NO2+, while NO+ or its carrier N2O3 is the attacking species in the latter reaction.

Intramolecular amidoselenation leading to lactams by the reaction of N-alkylalkenamides with benzeneselenenyl chloride

Abstract The reaction of N-alkylalkenamides (1)-(4) with benzeneselenenyl chloride affords γ- or δ-lactams (7)-(10) in good to excellent yields through the intramolecular attack of the nitrogen atom of the amide group on episelenonium ion intermediates.

An improved method for olefin synthesis using pyridylseleno group as a leaving group

Abstract Alkyl pyridyl selenides are oxidized by 1.5 equiv. of 30% H 2 O 2 in the THF to give olefins in good to excellent yields. The yields are always higher than the case where alkyl phenyl selendies are used under the same conditions.