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3 results on '"Tadashi Urai"'

1. Formation and reaction of 2-metalated N-Boc-4,4-dimethyl-1,3-oxazolidines in the presence of (−)-sparteine: new chiral formyl anion equivalents

Author

Tadashi Urai, Naoki Kise, and Jun-ichi Yoshida

Subjects
Chemistry, Stereochemistry, Organic Chemistry, Sparteine, Catalysis, Adduct, Ion, Inorganic Chemistry, Benzaldehyde, chemistry.chemical_compound, Equivalent, medicine, Physical and Theoretical Chemistry, medicine.drug
Abstract

Lithiation of N -Boc-4,4-dimethyl-1,3-oxazolidine with s -BuLi and the following reaction with benzaldehyde was carried out in the presence of (−)-sparteine. The reaction was not diastereoselective ( syn : anti =46:54), but each isomer of the adducts was obtained enantioselectively ( syn : 90% ee, anti : 88% ee). Addition of MgBr 2 to the reaction mixture increased the diastereoselectivity to syn : anti =90:10.

Published
1998

2. Self-induced porphyrin dimer formation via unusual atropisomerization of tetraphenylporphyrin derivative

Author

Ayato Kawashima, Tadashi Urai, Hisanobu Ogoshi, and Yasuhisa Kuroda

Subjects
chemistry.chemical_compound, chemistry, Hydrogen bond, Dimer, Organic Chemistry, Drug Discovery, Tetraphenylporphyrin, Photochemistry, Biochemistry, Porphyrin, Isomerization, Derivative (chemistry)
Abstract

Atropisomerization of meso-tetrakis( 2 -carboxy-4-nonylphenyl)porphyrin 1 , in nonpolar solvents such as CHCl 3 gives the αααα isomer exclusively, while the same isomerization in polar solvents such as DMSO proceeds normally. Spectroscopic investigations of 1 suggest that the porphyrin exists as a cofacial dimer in nonpolar solvents, where eight hydrogen bonds among tour pairs of carboxylic acids in 1 are formed.

Published
1995

3. ChemInform Abstract: Formation and Reaction of 2-Metalated N-Boc-4,4-dimethyl-1,3-oxazolidines in the Presence of (-)-Sparteine: New Chiral Formyl Anion Equivalents

Author

Jun-ichi Yoshida, Naoki Kise, and Tadashi Urai

Subjects
Benzaldehyde, chemistry.chemical_compound, Equivalent, Chemistry, Sparteine, medicine, General Medicine, Medicinal chemistry, medicine.drug, Ion, Adduct
Abstract

Lithiation of N -Boc-4,4-dimethyl-1,3-oxazolidine with s -BuLi and the following reaction with benzaldehyde was carried out in the presence of (−)-sparteine. The reaction was not diastereoselective ( syn : anti =46:54), but each isomer of the adducts was obtained enantioselectively ( syn : 90% ee, anti : 88% ee). Addition of MgBr 2 to the reaction mixture increased the diastereoselectivity to syn : anti =90:10.

Published
2010

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