Kazushige Maruyama

Asymmetric induction in oxygenation of styrene catalyzed by cobalt schiff base complex

Abstract The oxygenation of styrene catalyzed by optically active cobalt Schiff base complexes in 2-propanol gives an enantiomer excess of 1-phenyl-ethanol. The asymmetric induction may be accomplished in two steps: addition of CoH species to styrene and decomposition of 1-phenylethyl hydroperoxide.

Conversion of 2′-hydroxychalcones to flavanones catalyzed by cobalt Schiff base complex

Abstract Co(salpr) catalyzes the conversion of 2′-hydroxychalcones to flavanones in methanol under oxygen. Base catalysis by Co(salpr) (OH) produced in situ is responsible for the reaction, which is found to proceed reversibly.

Substrate anion cobalt(III) complex intermediate in model quercetinase reaction using cobalt schiff base complex

Abstract 4′-Methoxyflavonolatocobalt(III) (salen), a key intermediate for model quercetinase reaction is synthesized. The complex undergoes dioxygenolysis of the heterocyclic ring in DMF by apparently a nonradical process.

Highly selective aldol reaction of dibenzoylmethanes with formaldehyde catalyzed by cobalt schiff base complex under neutral conditions

Abstract Coordinatively saturated hydroxocobalt(III) Schiff base complexes catalyze highly selective aldol reaction of dibenzoylmethanes with formaldehyde in methanol to give 1,3-dibenzoylpropanes, resulting from retro-Claisen reaction of 1,1,3,3-tetrabenzoylpropanes, which are obtained quantitatively in dichloromethane. Coordinatively saturated cobalt(III) Schiff base complexes ligating a substrate anion as a monodentate ligand is found to be the reactive species.

Catalysis by cobalt Schiff's base complexes in highly selective conversion of arylglyoxals to α-aryl-α-hydroxyacetic esters

Cobalt Schiffs base complexes catalyse highly selective conversion of arylglyoxals to α-aryl-α-hydroxyacetic esters in alcohols; Lewis acidity of CoIII species may be responsible for the catalysis.

Cobalt schiff base complex promoted retro-claisen reaction of 1-(2-hydroxyphenyl)-3-phenyl-1,3-propanediones and flavone formation

Abstract Co(salpr) promotes the conversion of 1-(2-hydroxyphenyl)-3-phenyl-1,3-propanediones to retro-Claisen reaction products and flavones in methanol under oxygen. Base catalysis by Co(salpr)(OH) produced in situ is responsible for the reaction.

Separation and quantitative determination of monoacylglycerol mixtures by reversed phase HPLC

The separation and quantitative determination of underivatized saturated and unsaturated monoacylglycerol were examined by reversed phase high performance liquid chromatography using acetonitrile/water as the mobile phase. Monoacylglycerol (MG) mixtures containing saturated MG (C6-MG-C18-MG), monooleoylglycerol and monolinoleoylglycerol were sufficiently resolved, but mixtures of 1-MG and 2-MG with the same acyl group could not be separated under the conditions given below: column, C-8 chemical bonded column (4.6 × 250 mm); sample solvent, diethyl ether (UV detector at 210–215 nm) or chloroform; mobile phase, acetonitrile/water (7:3, v/v). Quantitative determinations were made for mixtures of three components (representative standard MGs) on a reversed phase column (Unisil Q, C-8) using a UV detector and the internal standard method. Standard deviation and coefficient of variation gave accurate, reproducible results.

Separation and estimation of anionic surfactants by thin layer chromatography: i. Mixtures of sodium dodecyl benzenesulfonate, sodium dodecyl sulfate and sodium dodecanesulfonate

The conditions for separation and quantitative determination of anionic surfactants such as sodium dodecylbenzenesulfonate, sodium dodecanesulfonate and sodium dodecyl sulfate by thin layer chromatography (TLC) were investigated. Analytical results for mixtures of 2 or 3 components under optimal TLC conditions were in satisfactory agreement with known values. The absolute errors and variation coefficients both were within ca. 4%.

Cobalt-Schiff Base Complex Catalyzed Epoxidation of Olefins with Naoc1

Abstract Cobalt-Schiff base complexes are found to catalyze the oxidation of olefins with NaOCl to give mainly epoxides together with vic -dichloro- and α-chlorocarbonyl compounds. The reaction rate depended on the nature of the cobalt catalyst as well as the structure of the olefin substrate. Proposed mechanism involves rate determining homolytic cleavage of the Co-O bond in Co III (L)(OCl), a hypochloritocobalt complex intermediate, under the interaction with the substrate.

Field control of regioselectivity in CoIII(salpr)(OH) promoted oxygenation of 4-aryl-2,6-di-tert-butylphenols

Abstract In the Co III (salpr)(OH) catalyzed oxygenation of 4-aryl-2,6-di- tert -butylphenols, the position of dioxygen incorporation is completely controlled by the nature of solvent; dioxygen incorporation occurs only at ortho position in an uncoordinative solvent leading to the corresponding peroxy- o -quinolatocobalt(III)(salpr), whereas dioxygen is unexpectedly incorporated into para position in coordinative amines to give p -quinols quantitatively.