The regiospecific cobalt carbonyl catalyzed synthesis of dienones and trienones by phase transfer catalysis

The phase transfer catalyzed, cobalt carbonyl catalyzed reaction of dienes, and a triene, with methyl iodide and carbon monoxide [r.t., 1 atm. P] is highly regiospecific, affording E-conjugated enones.     

Selective reduction of aromatic nitro compounds affording aromatic amines under CO/H2O conditions catalyzed by phosphine-added rhodium and ruthenium carbonyl complexes

High catalytic activities for the selective reduction of aromatic nitro compounds to the corresponding amines under the mild reaction conditions of room temperature and 1 atm of CO were found to be exhibited by chelatephosphine (dppe, dppm, etc.; dppe: 1,2-bis(diphenylphosphino)ethane, dppm: bis(diphenylphosphino)methane)-added rhodium and ruthenium carbonyl complexes in a 5 N NAOH aqueous solution. The reduction proceeded not only with high catalytic activities, but also with remarkably high nitro group selectivities; for example, 1-nitroanthraquinone afforded 1-aminoanthraquinone without other unsaturated groups (such as CO) being reduced. PR₃-added Rh(CO)₂(acac) complexes (PR₃: PEtPh₂, PEt₂Ph, PEt₃, etc.; acac: acetylacetonato) in diglyme in a 5 N NaOH aqueous solution were also found to show significant catalytic activities for the reduction of aromatic nitro compounds under mild CO/H₂O conditions. Both electronic and steric factors of phosphine ligands are important in making this reaction proceed at such remarkable rates.     

Homogeneous catalysis by ruthenium carbonyl clusters

The historical background of and the incentive for using ruthenium carbonyl clusters as homogeneous catalysts are outlined. Keeping in view the possible solutions the uncertainties arising from declusterification and metal colloid formation are discussed. All ruthenium cluster-catalysed reactions are broadly classified as reactions with or without carbon monoxide as one of the reactants and the basic differences between such reactions are highlighted. Some of the factors of special relevance to cluster-catalysed reaction systems are mentioned. The reactions involving carbon monoxide are then discussed. These include water-gas-shift reaction, carbon monoxide hydrogenation, hydroformylation, reductive carbonylation of nitrobenzene and other carbonylation reactions. Hydrogenation, transfer hydrogenation, isomerisation and a few other reactions are then discussed. For all these reactions, special emphasis is laid on well-characterised cluster complexes that have been proposed as catalytic intermediates. Finally an attempt has been made to identify the path that future research in cluster catalysis is likely to follow.     

Cobalt carbonyl catalyzed sRN1 carbonylation of aryl and vinyl halides by phase transfer catalysis

The phase transfer catalyzed, cobalt carbonyi catalyzed carbonylation (1 atm. P.) of aryl and vinyi bromides under photostimulation (350 nm) affords the corresponding unsaturated acids in high yield.     

The reduction of aromatic nitro compounds by oxiranes

Aromatic nitro compounds are reduced to the corresponding amines by epoxides at elevated temperatures (>170 °C).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1491–1494, August, 1994.The authors are grateful to Prof. Yu. N. Belokon' for his participation in the discussion of the results of the work.This work was financially supported by the Russian Foundation for Basic Research (code No. 93-03-18044).     

Regiospecific solvent-free transfer hydrogenation of α,β-unsaturated carbonyl compounds catalyzed by a cationic ruthenium(II) compound

[(PPh₃)₂Ru(CH₃CN)₃Cl][BPh₄] has been found to catalyze the selective reduction of double bonds in α,β-unsaturated ketones with high conversions when formic acid is the hydrogen donor.     

Rapid catalytic transfer reduction of aromatic nitro compounds to hydroxylamines

A general method has been developed for the rapid, metal-catalysed transfer reduction of nitro compounds to N-substituted hydroxylamines.     

Graphite catalyzed reduction of aromatic and aliphatic nitro compounds with hydrazine hydrate

Aromatic and aliphatic nitro compounds were readily reduced to amino compounds in excellant yields with graphite and hydrazine hydrate.     

Selective reduction of dimethyl oxalate by ruthenium carbonyl carboxylates in homogeneous phase Part IV

Ethylene glycol may be obtained selectively from dimethyl oxalate by hydrogenation in homogeneous phase in the presence of Ru₂(CO)₄(CH₃COO)₂(P^tPr₃)₂. In order to avoid decomposition of the substrate the hydrogenation must be carried out at 120 °C to completely convert the oxalic diester and then at 180 °C to hydrogenate the intermediate methyl glycolate.     

Allyl isomerization mediated by cyclopentadienyl ruthenium carbonyl compounds

Three new diruthenium complexes, namely (η ⁵-C₅H₄C(CH₂)₄CH=CHCH₃)₂Ru₂(CO)₂(μ-CO)₂ (1), (η ⁵-C₅H₄CEt₂CH=CHCH₃)₂Ru₂(CO)₂(μ-CO)₂ (2), and (η ⁵-C₅Me₄CH=CHCH₃)₂Ru₂(CO)₂(μ-CO)₂ (3), were synthesized and characterized by elemental analysis, IR and ¹H-NMR spectra. The crystal structures of complexes 1 and 2 were determined by X-ray single-crystal diffraction and showed that the allyl reagents used in their synthesis underwent isomerization to give the corresponding methyl–vinyl complexes. The X-ray crystal structures of complexes 1 and 2 confirm the presence of both bridging and terminal CO groups. A possible mechanism for the observed alkene isomerizations is discussed.     

Conjugate reduction of alpha,beta-unsaturated carbonyl compounds catalyzed by a copper carbene complex

[reaction: see text] An N-heterocyclic carbene copper chloride (NHC-CuCl) complex (2) has been prepared and used to catalyze the conjugate reduction of alpha,beta-unsaturated carbonyl compounds. The combination of catalytic amounts of 2 and NaOt-Bu with poly(methylhydrosiloxane) (PMHS) as the stoichiometric reductant generates an active catalyst for the 1,4-reduction of tri- and tetrasubstituted alpha,beta-unsaturated esters and cyclic enones. The active catalytic species can also be generated in situ from 1,3-bis(2,6-di-isopropylphenyl)-imidazolium chloride (1) CuCl(2).2H(2)O in the presence of NaOt-Bu and PMHS.     

Selective reduction of carbonyl compounds by diphenylstibine

Carbonyl compounds were selectively reduced by diphenylstibine in the presence of Lewis acid.     

阴离子相转移催化的Friedel-Crafts烷基化反应

提出三种阴离子表面活性剂十二烷基苯磺酸钠、十二烷基磺酸钠、十二烷基硫酸钠作为阴离子相转移催化剂特性。研究了它们在Friedel-Crafts反应中的催化性能,结果表明它们都有良好的催化特性合成了七个化合物, 其中五个为未见文献报导的新化合物, 它们是二苯甲基萘酚和二苯甲基酚类化合物。     

Reflections on osmium and ruthenium carbonyl compounds

The development of transition metal cluster chemistry is traced from the early discoveries of metal-metal bonded systems through to some recent developments made in the area of high nuclearity osmium and rutherium cluster carbonyls. Emphasis is placed on developments made in the physical techniques used to establish the structures of the cluster complexes in the solid state and in solution. Recent developments in synthetic methods which lead to “rational” cluster synthesis are described, and the electron counting rules used to rationalise the observed structures of carbonyl clusters are reviewed. New high nuclearity cluster structures are described, and emphasis is placed on the ability of these systems to undergo reversible redox chemistry without the metal frameworks rearranging. This contrasts the situation observed for low nuclearity clusters, and illustrates the potential of the higher nuclearity clusters to act as electron sinks.     

Efficient method for the reduction of carbonyl compounds by triethylsilane catalyzed by PdCl2

The versatility of the palladium(II) chloride and triethylsilane system has been tested in the reduction of aromatic carbonyl compounds. The reaction takes place under mild conditions. This facile and efficient method affords high yields for the reduction of aldehydes and ketones to the corresponding alkanes.     

Photo-enhanced reduction of carbonyl compounds by sodium borohydride

The reduction of ketones and some esters by sodium borohydride is dramatically accelerated by uv irradiation. The reaction seems to proceed from the (n, π) excited state of the carbonyl compound. The photocatalytic effect is dependent on the solvent polarity and substituents on aromatic carboxylic acids and alcohols of esters.