Katsuyuki Ogura
Chiba University
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Featured researches published by Katsuyuki Ogura.
Tetrahedron Letters | 1995
Makoto Fujita; Hiroko Oka; Katsuyuki Ogura
Abstract A PdCl 2 (PPh 3 ) 2 /LiCl catalyst effectively promoted the cross-coupling reaction of trimethyl(4-pyridyl)stannane and aromatic polybromides to offer easy access to poly(4-pyridyl)-substituted aromatic compounds.
Tetrahedron | 1997
Motohiro Akazome; Makoto Noguchi; Osamu Tanaka; Atsuko Sumikawa; Tohru Uchida; Katsuyuki Ogura
Abstract The inclusion compounds of several alkyl phenyl sulfoxides by (R)-phenylglycyl-(R)-phenylglycine [ (R,R)- 1 ] were prepared by two different methods (sorption and crystallization). Alkyl phenyl sulfoxides entered crystalline (R,R)- 1 with high S-enantioselectivity except for methyl phenyl sulfoxide which was recognized with high and reverse enantioselectivity (R-from in 92% ee). From the X-ray crystallographic study of an inclusion compound of bis[(o-methylsulfinyl)benzyl]ether (3) and (R,R)- 1 , it is deduced that the reversal of enantioselectivity was achieved by the conformational change of phenyl groups on the dipeptide layer.
Tetrahedron Letters | 1998
Ken-ichi Ogu; Motohiro Akazome; Katsuyuki Ogura
Abstract Treatment of allylic alcohols ( 1 ) with a hexafluoropropene-diethylamine adduct (PPDA) gave α-fluoro-α-(trifluoromethyl)-γ,δ-unsaturated amides ( 2 ), which were shown to be important precursors for synthesizing a variety of fluoro(trifluoromethyl)methylene-containing compounds.
Tetrahedron Letters | 1997
Katsuyuki Ogura; Ken-ichi Ogu; Takashi Ayabe; Jun-ichi Sonehara; Motohiro Akazome
Abstract ( E )-3-Hydroxy-1-alkenyl p -tolyl sulfones ( 1 ) reacted with a hexafluoropropene-diethylamine adduct (PPDA) to afford α-fluoro-α-(trifluoromethyl)-β-[( p -tolylsulfonyl)methyl]-γ-lactones ( 2 ). This reaction is so stereoselective that only one diastereomer of 2 is detected in the reaction mixture. A plausible mechanism for this intriguing reaction is discussed.
Tetrahedron | 1997
Akio Kayano; Motohiro Akazome; Makoto Fujita; Katsuyuki Ogura
Abstract Efficient 1,2-asymmetric induction was realized in the addition of a 1-hydroxyalkyl radical (R2C-OH) to 3-hydroxy-1-(methylthio)-1-(p-tolylsulfonyl)-1-alkenes and their acetates (1): Irradiation of 1 and benzophenone in an alcohol (R2CHOH) gave an adduct (2) with a high syn selectivity. Optically active 1 is easily obtainable by means of Lipase PS-catalyzed transesterification and, therefore, the present radical asymmetric induction provides a synthetic route leading to various chiral compounds.
Tetrahedron-asymmetry | 1997
Motohiro Akazome; Hirozumi Matsuno; Katsuyuki Ogura
Abstract An unprotected dipeptide, ( R )-phenylglycyl-( R )-phenylglycine, which is insoluble in water, was shown to be an excellent resolving reagent for racemic 1-arylethylamines. By simply stirring the mixture of the dipeptide and racemic 1-phenylethylamine in presence of water, asymmetric recognition occurred to give a salt of ( S )-1-phenylethylamine (95% ee) and the dipeptide. X-Ray crystallographic study of the salt elucidated the crystal structure of the diastereomeric salt, where hydrogen bonding and hydrophobic interaction between the dipeptide and amines play important roles in the construction of layers.
Journal of the American Chemical Society | 1995
Makoto Fujita; Yoon Jung Kwon; Osamu Sasaki; Kentaro Yamaguchi; Katsuyuki Ogura
Journal of the American Chemical Society | 1996
Makoto Fujita; Fumiaki Ibukuro; Hiroko Seki; Osamu Kamo; and Mamoru Imanari; Katsuyuki Ogura
Bulletin of the Chemical Society of Japan | 1996
Hiroshi Tomori; Hisayoshi Yoshihara; Katsuyuki Ogura
Bulletin of the Chemical Society of Japan | 1996
Hiroshi Tomori; Kuniko Shibutani; Katsuyuki Ogura