| Co-Investigator(Kenkyū-buntansha) |
YAMAMOTO Yasunori Hokkaido Univ., Grad. School of Eng., Inst., 大学院・工学研究科, 助手 (30271646)
ISHIYAMA Tatsuo Hokkaido Univ., Grad. School of Eng., Asso, Prof., 大学院・工学研究科, 助教授 (00232348)
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| Budget Amount *help |
¥13,300,000 (Direct Cost: ¥13,300,000)
Fiscal Year 2001: ¥4,800,000 (Direct Cost: ¥4,800,000)
Fiscal Year 2000: ¥8,500,000 (Direct Cost: ¥8,500,000)
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| Research Abstract |
1). Development of Water-soluble Phosphine Ligand (Miyaura, Ishiyama)
A Water-soluble phosphine ligand, N-(4-diphenyl-phosphino)phenylmethyl gluconanude(GLCAphos), was newly synthesized to perform the palladium-catalyzed biaryl coupling of arylboronic acids in a single aqueous media.
2). Coupling and Addition Reaction of Organoboronic Acid in Aqueous Solution (Miyaura, Ishiyama, Yamamoto)
The catalyst prepared from GLCAphos revealed higher activity than that synthesized from Ph_2P(m-C_6H_4SO_3Na) or P(m-C_6H_4SO_3Na)_3 for various haloarenes.
The rhodium-catalyzed conjugate addition of tolylboronic acid to α,β-unsaturated ketones, ester or amides was carried out in water. [RhCl(cod)]_2 and 2β-cyclodextrin-[Rh(OH)(cod)]_2 complex were found to catalyzed the reaction efficiently in a single aqueous medium.
3). Development of Enantioselective Michael Reaction (Ishiyama, Yamamoto)
Arylboronic acids underwent the conjugate 1,4-addition to α,β-unsaturated ester to give β-arylesters in high yields
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in the presence of a rhodium(I) catalyst. The addition of arylboronic acids to isopropyl crotonate resulted in high yield and high enantioselectivity exceeding 90 % ee in the presence of 3 mol % of Rh(acac)(C_2H_4)_2 and (S)-BINAP at 100 ℃. The rhodium/(S)-BINAP complex provided (R)-3-phenylbutanoate in the addition of phenylboronic acid to benzyl crotonate. The effects on the enantioselectivity of chiral phosphine ligands, rhodium precursors, and substituents on α,β-unsaturated esters are discussed, as well as the mechanistic aspect of the catalytic cycle.
The conjugate addition of arylboronic acids to α,β-unsaturated amides was carried out in the presence of a chiral rhodium catalyst and an aqueous base. The catalyst prepared in situ from Rh(acac)(CH_2=CH_2)_2 and (S)-BINAP provided (R)-N-benzyl-3-phenylbutanamide with 93 % ee in the addition of phenylboronic acid to N-benzyl crotonamide. The reaction suffered from incomplete conversion resulting in moderate yields, but addition of aqueous base, such as K_2CO_3(10-50 mol %) was found to be highly effective to improve the chemical yields. The role of the base giving a RhOH species active for transmetalation with arylboronic acid was discussed.
4). Coupling and Addition Reaction by the Polymer-bound Catalyst (Miyaura, Ishiyama, Yamamoto)
The cross-coupling reaction of tolylboronic acids (1.3 equiv.) with chloropyridines, chloroquinoline, or activated chloroarenes having an electron-withdrawing group was carried out in toluene at 80 ℃ in the presence of a polymer-bound PdCl_2 catalyst (3 mol %) and aqueous 2M K_3PO_4(2.6 equiv.). The Palladium-phosphine complex supported on a polystyrene-PPh_2 resin was reused with no significant decrease in activity. Less
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