|Budget Amount *help
¥24,000,000 (Direct Cost : ¥24,000,000)
Fiscal Year 2005 : ¥6,400,000 (Direct Cost : ¥6,400,000)
Fiscal Year 2004 : ¥6,400,000 (Direct Cost : ¥6,400,000)
Fiscal Year 2003 : ¥5,600,000 (Direct Cost : ¥5,600,000)
Fiscal Year 2002 : ¥5,600,000 (Direct Cost : ¥5,600,000)
1. Catalytic C-H Borylation
Direct C-H borylation of arenes catalyzed by a transition metal complex was studied as an economical protocol for the synthesis of a variety of arylboron compounds. Ir/bipyridine-catalyzed C-H borylation of arenes, heteroarenes, and benzylic positions of alkylarenes by bis(pinacolato)diboron or pinacolborane furnished aryl-, heteroaryl-, and benzylboron compounds.
2. Carbon-Carbon Bond Formation via the Rhodium Catalyzed Addition Reactions in aqueous medium
Various rhodium(I) complexes catalyzed the 1,4-addition of organoboronic acids to a,β-unsaturated carbonyl compounds or the Grignard-type addition to aldehydes in a mixture of an organic solvent and water. The reaction provided a convenient method for the asymmetric carbon-carbon bond formation. The rhodium-catalyzed conjugate addition of arylboronic acids to a,β-unsaturated ketones, esters or amides was carried out in water. A complex between [RhCl(cod)]_2 and 2β -cyclodextrin-[Rh(OH)(cod)]_2 catalyzed the
reaction efficiently in a single aqueous medium.
3. Chiral Bis-phosphoramidites for Asymmetric Rhodium-Catalyzed 1,4-Additions
A chiral bidentate phosphoramidite (BIPAM) was synthesized from Shibasaki's linked-(R)-BINOL and P(NMe_2)_3 as a new ligand for rhodium(I)-catalyzed asymmetric 1,4-addition of arylboronic acids to a,β-unsaturated carbonyl compounds. The effects of BIPAM and Feringa's monodentate phosphoramidite on the yields and enantioselectivities were investigated. The reaction was significantly accelerated in the presence of a base such as KOH and Et3N, allowing the reaction to be completed at the lower temperatures than 50℃.
4. Palladium-Catalyzed Addition Reactions of Organoboron compounds.
An enantioselective synthesis of cyclic and acyclic β-aryl ketones and esters via palladium(II)-catalyzed 1,4-addition of Ar-[m] (m=B(OH)_2, BF_3K, Si(OMe)_3, SiF_3, BiAr_2) to α, β-unsaturated ketones or esters is discovered. The enantioselection mechanism and efficiency of a chiraphos ligand for structurally planar α, β-unsaturated ketones are discussed on the basis of the X-ray structure of the catalyst and results of DFT computational studies on the modes of coordination of the substrates to the phenylrhodium(I)/(S,S)-chiraphos intermediate. Less