Take-aki Mitsudo

Ruthenium catalyzed selective synthesis of enol carbamates by fixation of carbon dioxide

Abstract Secondary amines react with carbon dioxide and terminal alkynes in the presence of a catalytic amount of 4-1,5-cyclooctadiene) (6-1,3,5-cyclooctatriene)ruthenium [Ru(COD)(COT)] and tertiary phosphine in toluene to give enol carbamates in good yields with high regio- and stereoselectivity. Cyclic enol carbamates, 5-methylene-2-oxazolidinones are obtained from N-substituted propargylamines and carbon dioxide in high yields.

Ruthenium complex-catalyzed allylic alkylation of carbonucleophiles with allylic carbonates

Abstract Allylic carbonates except for allyl methyl carbonate reacted with carbonucleophiles such as ethyl acetoacetate in the presence of a catalytic amount of Ru(cod)(cot) [cod = cycloocta-1,5-diene, cot = cycloocta-1,3,5-triene] in N -methylpiperidine at 80°C to give the corresponding monoallylated carbonucleophiles in high yields with high regioselectivity. The regioselectivity was quite different from that in the palladium-catalyzed reactions. The allylation of carbonucleophiles using allyl methyl carbonate selectively gave the diallylated carbonucleophiles in high yields.

Ruthenium-catalyzed intramolecular hydroamination of aminoalkynes

Low-valent ruthenium complexes with a p-acidic ligand, such as Ru(h 6 -cot)(dmfm)2 [cot 1,3,5-cyclooctatriene, dmfm dimethyl fumarate] and Ru3(CO)12, showed high catalytic activity for the intramolecular hydroamination of aminoalkynes. The reaction is highly regioselective, in which a nitrogen atom is selectively attached to an internal carbon of alkynes to give five-, six-, and seven-membered nitrogen heterocycles as well as indoles in good to high yields.

Structural investigation on column-chromatographed vacuum residues of various petroleum crudes by 13C nuclear magnetic resonance spectroscopy

Proton and carbon-13 nuclear magnetic resonance spectroscopy of various vacuum residues and their fractionated samples were carried out to investigate average molecular structures. The structural parameters derived from carbon distribution agreed with those derived from p.m.r. within experimental error. In the aliphatic region of the c.m.r. spectra, characteristic peaks assignable to (CH2)n − n ≧ 6 (29.7 ppm) and CH3CH2CH2CH2 (14.1 ppm) etc. can be observed. The relative intensities of these peaks suggest that the methylene chain contained in vacuum residues is much longer ((CH2)n − n ≧ 12) than has been considered previously. Using the information about the aliphatic region of the c.m.r. spectrum and the structural parameters, an average structural model was deduced.

Novel organic syntheses catalyzed by (cyclooctadiene) (cyclooctatriene) ruthenium and its derivatives

Abstract The characteristic catalytic activities of low valence ruthenium complexes, (cyclooctadiene)(cyclooctatriene)ruthenium and its derivatives, in organic syntheses have been exhibited by reviewing the recently developed novel reactions; (1) the first linear co-dimerization of acetylenes with 1,3-dienes (2) the [2 + 2] cross cycloaddition of norbornenes with dimethyl acetylenedicarboxylate (3) the addition of carboxylic acid to acetylenes giving enol esters.

Ruthenium complex catalyzed selective addition of carboxylic acids to acetylenes giving enol esters

Carboxylic acids react with acetylenes in the presence of a catalytic amount of bis(η5-cyclooctadienyl)ruthenium-PR3-maleic anhydride in toluene to give enol esters in good to excellent yields with high regioselectivity.

Selective photo-assisted catalytic oxidation of methane and ethane to oxygenates using supported vanadium oxide catalysts

Selective photooxidation of light alkanes, mainly methane and ethane, into the corresponding aldehydes was achieved using silica-supported vanadium oxide catalysts under UV irradiation at elevated temperature. Photooxidation of methane using the V2O5/SiO2-IW (incipient wetness) (0.6 mol% V) catalyst at 493 K for 2 h gave 68 µmol of methanal, which corresponds to 76 mol% selectivity and 0.48 mol% one-pass yield. Photooxidation of ethane using V2O5/SiO2 (calcined at 1023 K) -IW (0.6 mol% V) catalyst for 1 h gave 85 µmol of ethanal, which corresponds to 90% selectivity and 1.1% one-pass yield. The catalysts prepared by the sol–gel method also showed activity, especially for the reaction of ethane. Both UV irradiation and a reaction temperature as high as 500 K were essential. The photo-assisted catalytic reactions were very sensitive to the reaction temperature, method of preparation of the catalyst, and addition of water vapour. While the reaction of methane was inhibited by the addition of water vapour, the photooxidation of ethane and propane was promoted in the presence of a controlled amount of water vapour. In addition, the reaction with methane required UV irradiation at a wavelength <310 nm, whereas the reaction with ethane or propane proceeded by irradiation at longer wavelength. According to Raman and UV diffuse reflectance spectroscopic studies and XRD studies, only isolated four-coordinated vanadium oxide surface species were considered to show catalytic activity toward the photooxidation of methane, while accumulated vanadium surface species, not crystalline V2O5, were shown to be active for the photooxidation of ethane and propane.

Ruthenium complex-catalyzed selective syntheses of 3,5-dienoic acid derivatives by coupling of 1,3-dienes or allylic carbonates with acrylic compounds

Abstract Ru(cod)(cot) catalyzes highly selective codimerization of 1,3-dienes with acrylic compounds and first linear coupling reaction of allylic carbonates with the acrylic amide to give 3,5-dienoic acid derivatives; cod = cycloocta-1,5-diene, cot = cycloocta-1,3,5-triene.

Ru3(CO)12/1,10-phenanthroline-catalyzed hydroformylation of styrene and acrylic esters

Abstract The Ru 3 (CO) 12 /1,10-phenanthroline-catalyzed hydroformylation of styrene under 100 atm of syngas (CO:H 2 =1:1) at 120°C in DMF gives the corresponding branched and linear aldehydes in 58 and 22% yields, respectively. With the use of quinuclidine as a ligand in place of 1,10-phenanthroline in N , N -dimethylacetamide, the corresponding branched and linear oxo-alcohols were obtained in 53 and 28% yields, respectively. Hydroformylation of methyl acrylate by a catalyst system of Ru 3 (CO) 12 /1,10-phenanthroline to afford 4-methoxy-4-methyl- δ -valerolactone 1 in 31% yield, while the catalyst system of Ru 3 (CO) 12 /PPh 3 yields the open-chain aldehyde, dimethyl 2-formyl-2-methylglutarate ( 3 ), which is the precursor of lactone 1 in 18% yield.

Syntheses of cyclohexonone derivatives by the ruthenium complex-catalysed reactions of allylic compounds with β-keto esters

Abstract Allylic compounds such as allyl alcohols and allylamines react with two equivalent moles of acetoacetates in the presence of a catalytic amount of Ru(cod)(cot) (cod = cycloocta-1,5-diene; cot = cycloocta-1,3,5-triene) at 100°C for 5 h to give cyclohexenone derivatives in high yields.