Tamon Okano

Catalytic hydrogenation of nitriles and dehydrogenation of amines with the rhodium(I) hydrido compounds [RhH(PPri3)3] and [Rh2H2(µ-N2){P(cyclohexyl)3}4]

[RhH(PPri3)3] and [Rh2H2(µ-N2){P(cyclohexyl)3}4] are active catalysts for the hydrogenation of nitriles under ambient conditions, producing primary amines selectively; they are also active for the dehydrogenation of amines at higher temperatures to give nitriles or imines.

Hydroformylation of olefins with paraformaldehyde catalyzed by rhodium complexes

The addition of formaldehyde to olefins is efficiently catalyzed by RhH2(O2COH)[P(i-Pr)3]2 and gives the corresponding aldehydes in neutral solution.

Carbonylation of benzyl chloride catalyzed by watersoluble palladium phosphine complex in a two-phase system

Abstract Benzyl chloride is carbonylated by water-soluble PdCl 2 [Ph 2 P( m -C 6 H 4 -SO 3 Na)] 2 in an aqueous NaOH/n-heptane, benzene, or anisole two-phase system to afford phenylacetic acid in 89–93% yields. Aqueous NaOH/n-BuOH system gives both phenylacetic acid and benzyl n-butyl ether in comparable yields. The reaction proceeds under atmospheric pressure of carbon monoxide at 50 °C. When the system is placed under CO atmosphere, carbon monoxide is absorbed immediately.

Synthesis and properties of crown ether-modified phosphines and their use as ligands in transition metal catalysts

Abstract A novel series of crown ether-modified triarylphosphines, 1,2-diphenylphosphino-2,3,5,6,8,9-hexahydro-1,4,7,10-benzotetraoxacyclodecin (IIIa) and its higher homolog (III) (common nomenclature is 3 n -diphenylphosphinobenzo-[3 n -crown- n ]ethers ( n = 4, 5, 6, and 7)), is reported. The thermodynamic parameters for the extraction of alkali metal picrates are evaluated. Phosphines III ( n = 5 and 6) form 1 : 1 stoichiometric crown-type complexes with na + and K + . The observed extractability is in good agreement with the cavity size selectivity concept. The thermodynamic parameters Δ H ° and T Δ S ° for the extractive complexation at dgC are −63 to −58 kJ/mol and −41 to −35 kJ/mol, respectively, thus Δ G ° is governed by the enthalpy term. These phosphines are applied to reactions in liquid-liquid or liquid-solid phases, as the auxiliary ligands of homogeneous palladium and rhodium catalysis. The catalytic activities correlated well with the extractabilities of the phosphine ligands. The compound [RhCl(cod)] 2 , combined with IIIc and IIId, shows high activities toward catalytic hydrogenation of potassium and caesium cinnamates, respectively. Replacement of allyl bromide with powdered sodium or potassium iodide in benzene to give allyl iodide are catalyzed by (τ-C 3 H 5 PdCl) 2 in the presence of phosphines III.

Meerwein-Ponndorf-Verley reduction of ketones and aldehydes catalyzed by lanthanide tri-2-propoxides.

Lanthanide tri-2-propoxides, Ln(i-PrO)3 (Ln=Nd, Eu, Gd, Dy, Er, Tm, Yb), are very efficient for the catalytic Meerwein-Ponndorf-Verley reduction. The catalytic activity of Gd(i-PrO)3 is about 103 times as high as that of Al(i-PrO)3. Compared with Gd(i-PrO)3, Yb(i-PrO)3 is less active for the reduction of ketones but is efficient for that of aldehydes.

Palladium-catalyzed, arylation of ethylene (the Heck reaction) under aqueous conditions

Abstract The palladium-catalyzed arylation of ethylene under aqueous or aqueous-organic solvent two-phase conditions has been studied using PdCl2L2 (L, phosphorus ligand) as the catalyst. Both aqueous NaHCO3-soluble and -insoluble bromoarenes possessing electron withdrawing groups react with ethylene to give the styrenes in good yields by water-soluble catalyst (L, (C6H5)2P(m-C6H4SO3Na (tppms) 1 . Bromoarenes possessing electron-donating groups react with difficulty but the reaction takes place with the corresponding iodoarenes to afford the products in moderate yields. The reaction of 3-bromobenzoic acid by water-insoluble (L, (C6H5)3P (tpp) 2 under two-phase conditions gave the product in a poor yield.

Palladium-catalyzed carbonylative coupling of iodobenzene and 2-methyl-3-butyn-2-ol under biphasic conditions: Formation of furanones

Abstract Carbonylative coupling of iodobenzene and 2-methyl-3-butyn-2-ol ( 4 ) in aqueous NaOH/benzene was carried out by using Pd(OAc) 2 /Ph 3 P/Bu 4 PBr ( A ) and Pd(OAc) 2 /Ph 2 P(m-C 6 H 4 SO 3 Na) ( B ) as catalyst. In sharp contrast with a homogeneous Et 3 N solution, this biphasic solvent system gives 3-isopropylidene-5-phenyl-2(2H)-furanone ( 1 ) in a moderate yield. The other carbonylated products are 2,2-dimethyl-5-phenyl-3(2H)-furanone ( 2 ) and benzoic acid. The formation of 1 is explained by the following sequential reactions; carbonylative coupling of iodobenzene with 4 to form 4-hydroxy-4-methyl-1-phenyl-2-pentyn-1-one ( 6 ), hydrogenolysis of 6 to 4-methyl-1-phenyl-2,3-pentadien-1-one ( 8 ) and its cyclocarbonylation to 1 . Catalyst A gives 1 in a higher yield than B .

Palladium-catalyzed arylation of ethylene. A synthetic route to styrenes, stilbenes, and poly(phenylene vinylene)s

Abstract Palladium-catalyzed arylation of ethylene (the Heck reaction) was studied using (chlorobenzene)Cr(CO)3 complexes (I) and dibromobenzenes (II). At 100°C styrenes and divinylbenzenes were the major products and stilbenes, and oligo- and poly(phenylene vinylene)s were not formed in the range from 2 to 40 atm of ethylene pressure. At 140°C the polymeric products were formed in low yields. Two-step strategy, which includes coupling reactions of dihalobenzenes with ethylene and subsequently with divinylbenzenes, was successful in yielding poly(phenylene vinylene)s (PPVs).

A Convenient and General Synthetic Method for Photochromic Fulgides by Palladium-Catalyzed Carbonylation of 2-Butyne-1,4-Diols

Abstract Palladium-catalyzed carbonylation of substituted 2-butyne-1,4-diols affords a variety of photochromic fulgides in one step. This methodology provides an alternative to the traditional method based on the Stobbe condensation.

Synthesis and spectroscopic characterization of σ-bonded phenothiazinonepalladium complexes

Treatment of 4-iodo-3 H-phenothiazin-3-one with tetrakis(triphenylphosphine)-palladium(0) in boiling benzene yields trans-iodo(3H-phenothiazin-3-one-4-yl)bis (triphenylphosphine)palladium(II) by oxidative addition. 5H-Benzo[a]phenothiazin-5-one-6-yl complex is prepared in a similar manner. The σ-bonded iminoquinone structure of the complexes has been elucidated by1H,13C, and31P NMR spectroscopy.