Tsutomu Shin-ike

A Zinc(II)-Included Hemicryptophane: Facile Synthesis, Characterization, and Catalytic Activity

A zinc(II)-included hemicryptophane, which has a zinc(II) center embedded in the cavity, was synthesized and characterized. The catalytic activity of the hemicryptophane was tested in the hydrolysis of methyl para-nitrophenyl carbonate (MPC). A direct comparison between the hemicryptophane and the model complex, which lacks a cavity, demonstrated that the cage structure enhanced the catalytic activity.

Novel selenium catalyzed synthesis of isothiocyanates from isocyanides and elemental sulfur

Abstract A variety of aliphatic and aromatic isothiocyanates were synthesized in good to excellent yields from corresponding isocyanides and elemental sulfur under mild conditions by use of catalytic amounts of elemental selenium.

Platinum-Catalyzed Intramolecular Vinylchalcogenation of Alkynes with β-Phenylchalcogeno Conjugated Amides

Platinum-catalyzed intramolecular vinylthiolation and -selenation of internal alkynes with vinylchalcogenides 1 having a carbamoyl group on cis-beta-position of vinyl moiety was developed. The conjugated six-membered lactam framework 2 was constructed in high yields. Density functional theory calculations for alkyne insertion processes suggest seven-membered platinacycle 3 is a kinetically favored intermediate of this catalytic system.

Palladium-catalyzed selenoacylation of allenes leading to the regioselective formation of functionalized allyl selenides.

Palladium-catalyzed regio- and stereoselective selenoacylation of allenes with selenol esters proceeded to produce functionalized allyl selenides with the acyl moiety at the inner carbon and the SePh group at the terminal carbon in high yields. A mechanism accounting for the observed regio- and stereoselectivities is proposed based on the results of DFT calculations.

Synthesis of 1,3-selenazoles and 2-imidazolin-5-selones from isoselenocyanates and isocyanides

Abstract 1,3-Selenazoles and 2-imidazolin-5-selones were synthesized by the reaction of isoselenocyanates (1) with α-lithiated isocyanides (11). Isocyanides having only one substituent at the α-carbon such as ethyl isocyanoacetate and benzyl isocyanide gave 1,3-selenazoles (9) in good yields. On the other hand, α,α-disubstituted isocyanides such as α-methylbenzyl isocyanide and diphenylmethyl isocyanide afforded 2-butylseleno-2-imidazolin-5-selones (18) after trapping with butyl iodide. The latter products were formed from one molecule of isocyanides and two molecules of isoselenocyanates. Plausible reaction pathways are proposed.

On the pyrochlore type Ln2V2O7 (Ln: Rare-earth elements)

Pyrochlore type rare-earth vanadites (Ln2V2O7) were prepared and some physical properties were investigated. Ln2V2O7 (Ln:Tm, Yb or Lu) crystallized in the cubic space group Oh = Fd3m, a0 = 9.9575A, 9.9346Aand 9.9231A for Tm2V2O7, Yb2V2O7 and Lu2V2O7, respectively. These compounds were all n-type semiconductors and paramagnets in the temperature range 90–300K.

A marvelous catalysis of tellurium in the formation of isothiocyanates from isocyanides and sulfur

Abstract Catalytic activity of tellurium in the formation of isothiocyanates from isocyanides and sulfur has been found to be extremely high and far superior to that of selenium.

Electrical conductivity of LnVO3 compounds

Rare-earth vanadites LnVO/sub 3/ (Ln = La-Lu and Y) were prepared. These compounds have a perovskite-type structure with space group Pbnm. Electrical conductivity of each LnVO/sub 3/ has been studied in vacuum below room temperature. Results show that all rare-earth vanadites are extrinsic, p-type semiconductors having an activation energy of about 0.1 eV. Resistivity increases along the lanthanide series from LaVO/sub 3/ to GdVO/sub 3/ with quasi-constant values observed between TbVO/sub 3/ and LuVO/sub 3/. These results are discussed in terms of Goodenoughs localized electron model.

Studies on the solid solutions of Ln1−xSrxVO3−0.1x

Abstract Solid solutions (Ln 1−x Sr x VO 3−0.1x ; Ln:La, Nd, Eu, Gd, Er or Yb) composed with rare-earth vanadites (LnVO 3 ) and strontium vanadite (SrVO 2.9 ) and resulted from the reaction of Ln 2 O 3 , V 2 O 3 and SrO were studied. If the value of x in Ln 1−x Sr x VO 3−0.1x was lower than a certain value, crystals isostructural with LnVO 3 (Ln:La, tetragonal cell; Ln:Nd, Eu or Gd, orthorhombic cell) were obtained; if the value of x was higher than that, the products belonging to a cubic system isomorphous with SrVO 2.9 , were formed in the case of La, Nd, Eu or Gd. As the ionic radius of the incorporated rare-earth ion becomes larger, the region of the cubic-phase formation increases in size.

Preparation and some properties of K2NiF4 type Eu(II) vanadites

Europium vanadites, containing bi-valent europium, were synthesized by reacting Eu2O3, V2O3 and V. The vanadites obtained were EuO·EuVO3 and EuO·2EuVO3. The crystal structures and some physical properties of these compounds were studied.