Toshihide Baba

Asymmetric 1,3-dipolar cycloaddition reactions of nitrile oxides catalyzed by chiral binaphthyldiimine-Ni(II) complexes.

Asymmetric cycloaddition reactions between several nitrile oxides and 3-(2-alkenoyl)-2-oxazolidinones and 2-(2-alkenoyl)-3-pyrazolidinone derivatives were carried out in the presence of chiral binaphthyldiimine (BINIM)-Ni(II) complexes as catalysts. Using (R)-BINIM-4(3,5-xylyl)-2QN-Ni(II) complex (30 mol %), good regioselectivity (4-Me/5-Me = 85:15) along with high enantioselectivity (96% ee) of the 4-Me adduct were obtained for the reaction between isolable 2,4,6-trimethylbenzonitrile oxide and 3-crotonoyl-5,5-dimethyl-2-oxazolidinone. Substituted and unsubstituted benzonitrile oxides and aliphatic nitrile oxides, which were generated from the corresponding hydroximoyl chloride in the presence of MS 4A, were reacted with 3-crotonoyl-5,5-dimethyl-2-oxazolidinone, 5,5-dimethyl-3-(2-pentenoyl)-2-oxazolidinone, 5,5-dimethy-3-[3-(ethoxycarbonyl)propenoyl]-2-oxazolidinone, 1-benzyl-2-crotonoyl-5,5-dimethyl-3-pyrazolidinone, and 1-benzyl-2-[3-(ethoxycarbonyl)propenoyl]-5,5-dimethy-3-pyrazolidinone in the presence of (R)-BINIM-4Ph-2QN-Ni(II) or (R)-BINIM-4(3,5-xylyl)-2QN-Ni(II) complexes (10-30 mol %) as catalysts to give the corresponding cycloadducts in high yields, with high regioselectively (4-R/5-R = 85:15-99:1) and with moderate to high enantioselectivities (42-95% ee) of the 4-R adducts. Higher enantioselectivities and regioselectivities were obtained for the reactions using pyrazolidinone derivatives as the dipolarophiles. For the cycloadditions of 2-(2-alkenoyl)-1-benzyl-5,5-dimethyl-3-pyrazolidinones catalyzed by (R)-BINIM-4(3,5-xylyl)-2QN-Ni(II) complex (30 mol %), the enantioselectivity varied from 75% to 95% ee. The reactions between several nitrile oxides and 2-acryloyl-1-benzyl-5,5-dimethyl-3-pyrazolidinone in the presence of (R)-BINIM-4(3,5-xylyl)-2QN-Ni(II) complex (10 mol %) resulted in enantioselectivities (79-91% ee) that exceed those of previously reported enantioselective cycloadditions of acrylic acid derivatives. Furthermore, studies using a molecular modeling program using PM3 calculations were carried out to gain insight into the mechanisms of the asymmetric induction.

Metal cation–acidic proton bifunctional catalyst for methane activation: conversion of 13CH4 in the presence of ethylene over metal cations-loaded H-ZSM-5

Abstract It has been investigated that 13 CH 4 reacts with ethylene over metal cations such as indium cations-loaded H-ZSM-5 to form singly 13 C -labeled propylene ( 13 C 12 C 2 H 6 ) and hydrogen at 673xa0K. The heterolytic dissociation of Cue5f8H bond in methane presumably proceeds by the reaction of methane with metal cations for the formation of CH3δ+ and metal hydride species, thus allowing the reaction of CH3δ+ with ethylene to form propylene and acidic protons. Metal cations are regenerated by the reaction of silver-hydride species with acidic protons, and hydrogen is simultaneously formed. Thus, bifunctionality of metal cations and acidic protons is essential for the activation of methane.

Catalytic Methoxycarbonylation of Aromatic Diamines with Dimethyl Carbonate to Their Dicarbamates Using Zinc Acetate

The methoxycarbonylation of 2,4-toluene diamine and 4,4′-diphenylmethane diamine with dimethyl carbonate to the corresponding dicarbamates using zinc acetate was carried out at 453 K. Zn(OAc)2, prepared by evacuating Zn(OAc)2⋅2H2O at 383 K for 2 h, yields dimethyltoluene-2,4-dicarbamate in 96% yield in 2 h, while Zn(OAc)2⋅2H2O yields dimethyl-4,4′-methylenediphenyldicarbamate in 98% yield at 453 K in 2 h.The structure of methyl 3-amino-4-methyl phenyl carbamate, which is one of the intermediates for the reaction of 2,4-toluene diamine with dimethyl carbonate into dimethyltoluene-2,4-dicarbamate, has been determined by measuring the NOE spectrum of 1H NMR.

Conversion of methane into higher hydrocarbons in the presence of ethylene over H-ZSM-5 loaded with silver cations

H-ZSM-5 loaded with silver cations (Ag/H-ZSM-5) catalyzed conversion of CH4 to higher hydrocarbons such as C3H6 in the presence of C2H4. The effect of the reaction parameters, such as reaction temperature, were examined. The maximum conversion of methane was 13.2 mol% at 673 K. The reaction of C2H4 with 13C-labelled methane (13CH4) yielded singly 13C-labelled propylene (13CC2H6) and H2, while formation of 13CC2H6 was not observed over H-ZSM-5. These results indicate that the formation of 13CC2H6 proceeds by the reaction of C2H4 with 13CH4, and that the activation of 13CH4 proceeds on silver cations. Ag/H-ZSM-5 also catalyzed the reaction of nC3H6 and benzene with CH4 to form butenes and toluene, respectively.

Addition of silanes to benzaldehyde catalyzed by KF loaded on alumina

Abstract KF loaded on alumina heated under vacuum at 673 K (KF/Al 2 O 3 ) quantitatively gave benzyloxytriethylsilane by addition of triethylsilane to benzaldehyde at 303 K in N , N -dimethylformamide (DMF). KF/Al 2 O 3 also catalyzed the reaction of trimethylsilylacetonitrile with benzaldehyde to give 3-phenyl-3-(trimethylsilyloxy)propionitrile with a 81% yield at 313 K in tetrahydrofuran (THF) while it gave cinnamonitrile with a 61% yield in DMF, along with trimethylsilanol.

Acidic Character and Catalytic Activity of Sulpho-functionalized Porous Silica with an Ordered Structure

Microporous organosilica incorporating various amounts of sulpho groups (MS-SO3H) was prepared by hydrolysis and the co-condensation of tetramethoxysilane (TMOS) and mercaptopropyl trimethoxysilane (MPTMS), followed by oxidation of the thiol group. The resulting microporous silica had a regular porous structure similar to that of the mesoporous silica MCM-41, as shown by X-ray diffraction and nitrogen adsorption measurements. Ammonia adsorption microcalorimetry indicated that a large number of sulpho groups were successfully incorporated into the microporous silica framework. The sulpho group-incorporating microporous silica (MS-SO3H) exhibited catalytic activity towards the isomerization of but-1-ene to cis- and trans-but-2-ene via an acid catalysis mechanism.

Atmospheric occurrence of 2-nitrobenzanthrone associated with airborne particles in central Tokyo

2- and 3-Nitrobenzanthrones (NBAs) in airborne particles collected in central Tokyo on a seasonal basis from 1996 to 2001 are quantified and possible sources are investigated. The concentrations of 2- and 3-NBA are found to range from 49 to 831 fmol m–3and 0.5 to 3.5 fmol m–3, while the nitrated polycyclic hydrocarbons 1-nitropyrene and 2-nitrofluoranthene are found at concentrations of 100–492 fmol m–3 and 10–97 fmol m–3. Significant linear correlations are identified between 2-NBA and NO2, a photochemical product, suggesting that 2-NBA is formed by atmospheric reactions of benzanthrone initiated by hydroxyl or nitrate radicals in the presence of NO2. 2-NBA is not correlated with directly emitted compounds such as 1-nitropyrene. The concentration ratio of 2-NBA to 1-nitropyrene is 5 or greater in all samples. Nitrated polycyclic aromatic compounds formed by atmospheric reactions therefore appear to represent a substantial contribution to the mutagenicity of airborne particulate matter.

25 Catalytic synthesis of dimethyltoluene-2,4-dicarbamate by the methoxycarbonylation of 2,4-toluene diamine with dimethyl carbonate using Zn (OAc)2·2H2O

The methoxycarbonylation of 2,4-toluene diamine(TDA) and 4,4′-diphenylmethane diamine (MDA), with dimethyl carbonate to the corresponding dicarbamates using Zn compounds was carried out at 453 K. Zn(OAc)2·2H2O yields dimethyltoluene-2,4-dicarbamate in 92% yield in 2h, while it yields dimethyl-4,4′-methylenediphenyldicarbamate in 98% yield at 453 K in 2h. n nThe structure of methyl 3-amino-4-methyl phenyl carbamate, which is one of the intermediates for the reaction of 2,4-toluene diamine with dimethyl carbonate into dimethyltoluene-2,4-dicarbamate, has been determined by measuring NOE spectrum of 1H NMR.