Aldehydes catalysis, ruthenium complexes

Ruthenium complexes B are stable in the presence of alcohols, amines, or water, even at 60 °C. Olefin metathesis can be realized even in water as solvent, either using ruthenium carbene complexes with water-soluble phosphine ligands [815], or in emulsions. These complexes are also stable in air [584]. No olefination of aldehydes, ketones, or derivatives of carboxylic acids has been observed [582]. During catalysis of olefin metathesis replacement of one phosphine ligand by an olefin can occur [598,809]. 

Ruthenium complexes attract recent interest as new promising candidates for efficient, specific and environmentally benign allylation catalysts. It is noticeable that some J7 -allylruthenium(II) complexes have an ambiphilic property in catalysis involving the C-0 bond activation [52]. When allyl carboxylates or carbonates are treated with nucleophilic 1,3-dicarboxylates or electrophilic aldehyde in the presence of Ru complexes, catalytic allylations of nucleophiles or electrophiles take place [53]. In both reactions, J7 -allylruthenium complexes are assumed to be intermediates. Independent synthesis and reactions of the model compounds support this observation (Scheme 3.28). This ambiphilicity of the allylruthenium(II) may arise from the different reactivity of and rf forms in the allylic moiety [54]. 

Under catalysis by a ruthenium complex, N-methylmorpholine 7V-oxide rapidly oxidizes most alcohols to the corresponding aldehyde or ketone in high yield at room temperature. Homoallylic alcohols are exceptional, undergoing conversion at a slow rate, if at all. Preferential oxidation of primary, secondary diols at the secondary centre leading to keto-alcohols has been achieved by treatment of the bis-trityl derivative with trityl tetrafluoroborate. ... 

Secheresse reported size-controlled formation of silver nanparticles (43) by direct bonding of ruthenium complex 42 and silver nanoparticles. Oxazole 42 was formed by the reaction of diketone 40 and aldehydes 41 under the influence of NH4OAC. These metallic nanoparticles may find applications in DNA sequencing, catalysis, optics, nanoscale electronics and antimicrocrobials. ... 

Among the most significant developments in the field of catalysis in recent years have been the discovery and elucidation of various new, and often novel, catalytic reactions of transition metal ions and coordination compounds 13, 34). Examples of such reactions are the hydrogenation of olefins catalyzed by complexes of ruthenium (36), rhodium (61), cobalt (52), platinum (3, 26, 81), and other metals the hydroformylation of olefins catalyzed by complexes of cobalt or rhodium (Oxo process) (6, 46, 62) the dimerization of ethylene (i, 23) and polymerization of dienes (15, 64, 65) catalyzed by complexes of rhodium double-bond migration in olefins catalyzed by complexes of rhodium (24,42), palladium (42), cobalt (67), platinum (3, 5, 26, 81), and other metals (27) the oxidation of olefins to aldehydes, ketones, and vinyl esters, catalyzed by palladium chloride (Wacker process) (47, 48, 49,... 

Ligand-metal bifunctional catalysis provides an efficient method for the hydrogenation of various unsaturated organic compounds. Shvo-type [83-85] Ru-H/OH and Noyori-type [3-7] Ru-H/NH catalysts have demonstrated bifimctionality with excellent chemo- and enantioselectivities in transfer hydrogenations and hydrogenations of alkenes, aldehydes, ketones, and imines. Based on the isoelectronic analogy of H-Ru-CO and H-Re-NO units, it was anticipated that rhenium nitrosyl-based bifunctional complexes could exhibit catalytic activities comparable to the ruthenium carbonyl ones (Scheme 29) [86]. 

A chelation-assisted mthenium-catalyzed arylation of aldehyde 99 was accomplished in combination with a palladium complex [47]. This cooperative catalysis [48] proved applicable to organostannanes and aryl iodides as arylating reagents (Scheme 9.35). The direct arylation proceeded most likely through ruthenium-catalyzed C—H bond activation, subsequent transmetallation to palladium, and reductive elimination from a palladium intermediate. 

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