Young Keun Chung

Use of surfactants in water-soluble ruthenium(II) complex-catalyzed asymmetric hydrogen-transfer reduction of aromatic ketones

Abstract The introduction of surfactants to the water-soluble Ru(II)-catalyzed asymmetric transfer hydrogenation of ketones led to an increase of the catalytic activity and reusability compared to the catalytic systems without surfactants

Use of amino amides derived from proline as chiral ligands in the ruthenium(II)-catalyzed transfer hydrogenation reaction of ketones

We developed an efficient, easily available, and easy to use proline amide-based ruthenium(II) catalysts for the asymmetric hydride transfer reduction of prochiral ketones and e.e.s up to 98.8% have been measured.

Molybdenium mediated preparation of cyclopentenones

Abstract Cocyclization of alkynes, alkenes and carbon monoxide was achieved in the presence of a stoichiometric amount of molybdenium hexacarbonyl and excess of dimethylsulfoxide. This process will constitute another version of Pauson-Khand reaction.

Immobilized heterobimetallic Ru/Co nanoparticle-catalyzed Pauson–Khand-type reactions in the presence of pyridylmethyl formate

Heterobimetallic Ru/Co nanoparticles, immobilized on charcoal, were synthesized and used as catalysts in the Pauson-Khand-type reaction in the presence of pyridylmethyl formate instead of carbon monoxide; the catalysts were effective for intra- and intermolecular reactions and easily reused without loss of catalytic activity.

Synthesis of novel planar chiral ferrocene and cyclopentadienyl manganese tricarbonyl derivatives and their use as chiral ligands in the palladium-catalyzed asymmetric allylic alkylation

We have shown that cymantrene derivatives are better P,N-chelate ligands for palladium-catalyzed allylic alkylation than ferrocenes, which have a similar pentagonal ligand structure to cymantrene derivatives. In particular, the PPh 3 -substituted cymantrene gave a higher enantioselectivity (>98%).

An efficient preparation of 3-azabicyclo [3.3.0]. Oct-5-en-7-ones from propargyl alcohol- cobalt complexes via nicholas reaction with amidic nitrogen nucleophiles followed by pauson-khand cyclization

Abstract 3-Azabicyclo [3.3.0]-oct-5-en-7-ones were efficiently prepared from cobalt-propagyl alcohol complexes and various allyl amides via Nicholas reaction in the presence of BF3Et2O followed by Pauson-Khand cyclization promoted with trimethylamine N-oxide or SiO2.

PREPARATION AND PROPERTIES OF FERROCENYL BIMETALLIC COMPOUNDS FOR NON-LINEAR OPTICS

Abstract Ferrocenylbimetallic compounds of the form [CpFeC5H4ue5f8CHue5fbCHue5f8pyue5f8M(CO)n](M(CO)nue5fbMn(CO)5 + (4),Re(CO)5+ (5), W(CO)5 (6), Cr(CO)5 (7), and Fe(CO)4 (8)) have been synthesized by the ligation of the dangling pyridine to the metal carbonyl fragments, and their quadratic hyperpolarizabilities were determined using the hyper-Rayleigh scattering method. Manganese and rhenium carbonyl compounds showed considerable solvatochromism and have high hyperpolarizabilities.

Role of the planar chirality of imine–phosphine hybrid ligands bearing chromium tricarbonyl in the palladium-catalyzed asymmetric allylic alkylation

Optically active Cr-complexed imine–phosphine hybrid ligands having only a planar chirality showed excellent enantioselectivity for the palladium-catalyzed allylic alkylation with predictable absolute configuration.

Synthesis and non-linear optical properties of (alkyne)dicobalt octacarbonyl complexes and their substitution derivatives

A series of new donor/acceptor compounds of the form [(HC/C/CH/CH/C6H4/X-p )Co2(CO)4(L 1 )(L 2 )])] (2 ,X /Br, L 1 / L 2 /CO; 3 ,X /NO2 ,L 1 /L 2 /CO; 6 ,X /NO2 ,L 1 /CO, L 2 /PPh3; 7 ,X /NO2 ,L 1 /L 2 /PPh3; 8 ,X /NO2 ,L 1 /AsPh3, L 2 /PPh3), where X is a p-acceptor group and the (alkyne)Co2(CO)4(L 1 )(L 2 ) moiety is a donor, has been synthesized. The different s-donor/p-acceptor abilities of the ligands L 1 and L 2 allow tuning of the electronic and optical properties of complexes 2, 3 and 6/8: the hyperpolarizability values increase in the order 2 B/3 B/6 B/7 B/8. Density functional calculations reveal that the absolute values of b do not agree with experimental results, but the general trends are consistent with experiments. The X-ray crystal structures of 2, 6, and 7 are reported. # 2002 Elsevier Science B.V. All rights reserved.

Synthesis and antitumor activity of (diamine)platinum(ii) complexes of benzylmalonate derivatives

(Diamine)platinum(II) complexes of benzylmalonate derivatives as a leaving group designed in a wide range of lipophilicity and water-solubility were prepared and their antitumor activities were attempted to correlate to their lipophilicity or solubility. A good relationship was observed between their in vitro toxicity and solubility of the title complexes with the same carrier ligand, DACH (trans-(+/-)-1,2-diaminocyclohexane): The most soluble complexes are most cytotoxic whereas the least soluble complexes are least cytotoxic. However, no relationship could be established between their in vivo activity and their lipophilicity or solubility presumably due to other pharmacokinetic factors involved in vivo. The molecular structure of (IPA)2Pt(DBM).2CH3OH (IPA = isopropylamine; DBM = dibenzylmalonate) was determined by X-ray diffraction: space group P2(1)/n, a = 11.433 (3), b = 14.461 (4), c = 17.478 (4) A, beta = 97.25 (3) degrees, z = 4, R = 0.0437.