Tomohiro Yasukawa

Chiral ligand-modified metal nanoparticles possess an attractive potential for application in asymmetric synthesis. This article focuses on chiral-nanoparticle-catalyzed asymmetric C-C bond formation reactions and discusses the nature of the active species.

Robust and highly active bimetallic Rh nanoparticle (NP) catalysts, PI/CB Rh/Ag, have been developed and applied to the asymmetric 1,4-addition of arylboronic acids to enones without leaching of the metals. We found that the structures of the bimetallic Rh/Ag catalysts and chiral ligands strongly affect their catalytic activity and the amount of metal leaching. PI/CB Rh/Ag could be recycled several times by simple operations while keeping high yields and excellent enantioselectivities. To show t

We describe the use of chiral metal nanoparticle systems, as novel heterogeneous chiral catalysts for the asymmetric 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds, as representative C-C bond-forming reactions. The reactions proceeded smoothly to afford the corresponding β-arylated products in high to excellent yields and outstanding enantioselectivities with wide substrate scope. Remarkably, the nanoparticle catalysts showed performance in terms of yield, enantioselecti

The use of chiral ligand-modified metal nanoparticles is a promising strategy for constructing active and robust asymmetric catalyst systems. A recent advance in such catalyst systems for C–C bond-forming reactions is highlighted, and the characteristics of the active species are discussed. Several studies suggested that a redox event between nanoparticles and reagents might be a key to generating active species from nanoparticles.

Cellulose-supported chiral Rh nanoparticle (NP) catalysts have been developed. The Rh NPs, which were well dispersed on cellulose, catalyzed the asymmetric 1,4-addition of arylboronic acids to enones and enoates, one of the representative asymmetric carbon-carbon bond-forming reactions, in the presence of chiral diene ligands, providing the corresponding adducts in high yields with outstanding enantioselectivities without metal leaching. The solid-state NMR analysis of the chiral NP system direc

Cooperative catalysts consisting of chiral Rh/Ag nanoparticles and Sc(OTf)3 have been developed that catalyze asymmetric 1,4-addition reactions of arylboronic acids with α,β-unsaturated amides efficiently. The reaction has been considered one of the most challenging reactions because of the low reactivity of the amide substrates. The new catalysts provide the desired products with outstanding enantioselectivities (>98 % ee) in the presence of low loadings (<0.5 mol %) of the catalyst.

Abstract Cooperative catalysts consisting of chiral Rh/Ag nanoparticles and Sc(OTf) 3 have been developed that catalyze asymmetric 1,4‐addition reactions of arylboronic acids with α,β‐unsaturated amides efficiently. The reaction has been considered one of the most challenging reactions because of the low reactivity of the amide substrates. The new catalysts provide the desired products with outstanding enantioselectivities (&gt;98 % ee ) in the presence of low loadings (&lt;0.5 mol %) of the cat

Asymmetric arylation of aldimines catalyzed by heterogeneous chiral rhodium nanoparticles has been developed. The reaction proceeded in aqueous media without significant decomposition of the imines by hydrolysis to afford chiral (diarylmethyl)amines in high yields with outstanding enantioselectivities. This catalyst system exhibited the highest turnover number (700) in heterogeneous catalysts reported to date for these reactions. The reusability of the catalyst was also demonstrated.

Heterogeneous nitrogen-doped carbon-incarcerated cobalt/copper bimetallic nanoparticle (NP) catalysts, prepared from nitrogen-containing polymers, were developed, and an efficient catalytic process for aerobic oxidative esterification was achieved in the presence of a low loading (1 mol %) of catalyst that could be reused and easily reactivated. This protocol enabled diverse conditions for the bimetallic NP formation step to be screened, and significant rate acceleration by inclusion of a copper

Heterogeneous nitrogen-doped carbon-incarcerated iron/copper bimetallic nanoparticle (NP) catalysts prepared from nitrogen-containing polymers were developed. These catalysts showed activity higher than that of the corresponding monometallic NPs for aerobic ammoxidation of alcohols to nitriles. The important procedure for high activity in the catalyst preparation was found to be a simultaneous reduction of two metal salts.

Development of stable heterogeneous catalyst systems is a crucial subject to achieve sustainable society. Though metal nanoparticles are robust species, the study of asymmetric catalysis by them has been restricted because methods to activate metal nanoparticles without causing metal leaching were limited. We developed Rh nanoparticle catalysts (NCI-Rh) supported on nitrogen-doped carbon as a solid ligand to interact with metals for asymmetric insertion of carbenoids into N-H bonds cocatalyzed b

The development of heterogeneous catalyst systems for enantioselective reactions is an important subject in modern chemistry as they can be easily separated from products and potentially reused; this is particularly favorable in achieving a more sustainable society. Whereas numerous homogeneous chiral small molecule catalysts have been developed to date, there are only limited examples of heterogeneous ones that maintain high activity and have a long lifetime. On the other hand, metal nanopartic

Aerobic oxidation of aldehydes to 1,2- and 1,3-diol monoesters was catalyzed by polymer-incarcerated gold nanoclusters under ambient conditions. The esterification proceeded much faster with 1,2- and 1,3-diols and their derivatives rather than with methanol.

Aerobic oxidative cross-coupling reactions between alkynes and boronic acids under mild conditions catalyzed by low loadings of a copper salt are reported. 2,6-Lutidine accelerated the reactions dramatically, and the desired coupling products were obtained in high yields with high selectivities.