Ryouichi Akaishi
University of Tsukuba
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Featured researches published by Ryouichi Akaishi.
Tetrahedron Letters | 1991
Hisashi Fujihara; Takeshi Ninoi; Ryouichi Akaishi; Tomoki Erata; Naomichi Furukawa
A new cyclic bis-telluride, 1,5-ditelluracyclooctane (1), has been synthesized. Two-electron oxidation of 1 with two equivalents of NOBF4 or NOPF6 afforded a novel ditelluride dication BF4- or PF6- salt 2 which was characterized by 125Te NMR spectroscopy, and the dication 2 behaves as an oxidizing agent.
Tetrahedron | 1993
Hisashi Fujihara; Ryouichi Akaishi; Naomichi Furukawa
Abstract The disulfide dication salt, 1,5-dithioniabicyclo[3.3.0]octane bis(trifluoromethanesulfonate) ( 3 ), was isolated from the reaction of 1,5-dithiacyclooctane 1-oxide with trifluoromethanesulfonic anhydride. Two-electron oxidation of 1,5-diselenacyclooctane with two equivalents of NOPF 6 or NOBF 4 gave the first diselenide dication salt, 1,5-diselenoniabicyclo-[3.3.0]octane bis(hexafluorophosphate) or bis(tetrafluoroborate ( 5 ). The disulfide and diselenide dication salts ( 3 and 5 ) act as an oxidant or as an electrophile depending on the added reagents.
Journal of The Chemical Society, Chemical Communications | 1989
Hisashi Fujihara; Ryouichi Akaishi; Tomoki Erata; Naomichi Furukawa
A new cyclic bis-selenide, 1,5-diselenacyclo-octane (1) has been prepared; two-electron oxidation of (1) with two equivalents of NOPF6 gave a novel diselenide PF6– salt which acts as an oxidizing agent.
Tetrahedron Letters | 1990
Hisashi Fujihara; Ryouichi Akaishi; Akiko Nakamura; Naomichi Furukawa
Abstract The reaction of the diselenide dication salt, 1,5-diselenoniabicyclo[3.3.0]octane bis(hexafluorophosphate) ( 1 ) with 1,5-diselenacyclooctane ( 2 ) gave the corresponding cation radical by single-electron transfer. The dication salt 1 was reduced upon treatment with fluorenyl-lithium, Na 2 S, NaBH 4 ; it did not deprotonate. The cyclic voltammetry of 1 shows the reversible reduction peak at remarkably low reduction potential.
Tetrahedron Letters | 1989
Hisashi Fujihara; Ryouichi Akaishi; Naomichi Furukawa
Abstract A new cyclic tris-sulfide, 3,7,9-trithiabicyclo[3.3.1] nonane ( 1 ) has been synthesized. Transannular S-S interaction in 1 was found in the reactions of 1 and its sulfoxide with concd H 2 SO 4 and in electrochemical oxidation.
Journal of The Chemical Society, Chemical Communications | 1987
Hisashi Fujihara; Ryouichi Akaishi; Naomichi Furukawa
The reaction of 1,5-dithiacyclo-octane 1-oxide with trifluoromethanesulphonic anhydride affords the corresponding disulphide dication as a stable crystalline salt which serves as an oxidizing agent in the oxidation of 1,2-diphenylhydrazine; the disulphide dication of 1,4-dithiane has also been isolated.
Journal of The Chemical Society, Chemical Communications | 1989
Hisashi Fujihara; Ryouichi Akaishi; Naomichi Furukawa
The disulphide dication salt, 1,5-dithioniabicyclo[3.3.0]octane bis(trifluoromethanesulphonate)(1) was reduced upon treatment with carbanions or alkoxides; it did not deprotonate.
Bulletin of the Chemical Society of Japan | 1988
Fujiko Iwasaki; Nobuhiko Toyoda; Ryouichi Akaishi; Hisashi Fujihara; Naomichi Furukawat
Bulletin of the Chemical Society of Japan | 1989
Hisashi Fujihara; Ryouichi Akaishi; Naomichi Furukawa
Chemistry Letters | 1990
Hisashi Fujihara; Akiko Nakamura; Ryouichi Akaishi; Naomichi Furukawa