Catalysis ruthenium

Ruthenium salts were used in early reports of CDC reactions. As can be seen from the examples discussed below, the suggested roles of the catalyst were to oxidize the substrate, to complex to an iminium intermediate, to activate the nucleophile, or to facilitate nucleophilic addition. The use of a stoichiometric oxidant was necessary, with peroxides or molecular oxygen being common. The suggested role of the oxidant ranges from the conversion of the amine to the iminium ion or the re-generation of the catalyst. 

Ruthenium-catalyzed coupling reactions reported by Murahashi, and a composite proposed mechanism with added nucleophile. 

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Rhodium (2J) and ruthenium are excellent catalysts for the reduction of aromatic rings. It is with these catalysts that the best chance resides for preservation of other reducible functions (2,10,13,18,41,42,52). Rhodium (41) and ruthenium (45) each reduced methylphenylcarbinol to methylcyclohexyl-carbinol in high yield. Palladium, on the other hand, gives ethylbenzene quantitatively. Water has a powerful promoting effect, which is unique in ruthenium catalysis (36). 

Equation 11.43 Transfer hydrogenation of benzaldehyde with ruthenium catalysis. 

Aromatic imines can be ortho-arylated and alkenylated using ruthenium catalysis (Equation (129)).1... 

Trost reported the synthesis of 1,4-dienes with ruthenium catalysis through regioselective carbometallation of alkynes with alkenes.51 Di- and trisubstituted olefins can also be obtained with arylboronic acids through an intermolecular process under rhodium,30 52 55 nickel,56 and palladium catalysis.57 Recently, Larock has reported an efficient palladium-catalyzed route for the preparation of tetrasubstituted olefins.58,59... 

Dienes such as 90 can be accessed by a multi-component reaction under ruthenium catalysis involving an allene 88 and an enone (methyl vinyl ketone in this case), with cerium(m) chloride as an additive in DMF (Scheme 26).95,96 With an allene concentration of 0.25 M, yields are moderate to good. Different ruthenium catalysts and additives were tested in order to optimize this reaction. CpRu(COD)Cl 89 and CpRu(MeCN)3PF6 appeared to be more versatile ones. The mono-, di-, tri-, and tetrasubstituted allenes have been investigated with methyl vinyl... 

The chemistry of ruthenium has been reviewed in COMC (1982) and COMC (1995)338 339 as well as in Comprehensive Coordination Chemistry II. More recent reviews summarize the synthesis, properties, and applications of diruthenium tetracarboxylates341 as well as ruthenium catalysis in organic synthesis in general.342 Most recent developments and applications of ruthenium complexes in organic synthesis have been reviewed up to 2004.343... 

This excellent regiocontrol was exploited by subjecting terminal alkenes and hydroxyalkynoates to ruthenium catalysis conditions to afford butenolides and pentenolides (Equation (23)).36 The Alder-ene reaction occurs preferentially to form the G-G bond at the alpha-carbon of the alkynoate. The unusually high regioselectivity is attributed to a synergistic effect derived from an enhanced coordination of the hydroxyl group to the ruthenium. 

The ruthenium catalyst system, 14, shown in Fig. 3, also carries out ADMET condensation chemistry, albeit with higher concentrations being required to achieve reasonable reaction rates [32]. The possibility of intramolecular compl-exation with this catalyst influences the polymerization reaction, but nonetheless, ruthenium catalysis has proved to be a valuable contributor to overall condensation metathesis chemistry. Equally significant, these catalysts are tolerant to the presence of alcohol functionality [33] and are relatively easy to synthesize. For these reasons, ruthenium catalysis continues to be important in both ADMET and ring closing metathesis chemistry. 

Table 1. Rate constants showing the kinetic effect of functionalized monomers with molybdenum and ruthenium catalysis...

Diisopropenyl oxalate results from the addition of oxalic acid to propyne. The ester condenses with all types of amines under ruthenium catalysis to yield the corresponding ester amides or oxamides, depending on the amounts of amines used (equation 104)327. 

Carborundum, silver on, 27 10-12 3-Carboxy - 2,2,5,5,- tetramethylpyrrolidin-1-oxy m-nitrophenyl ester, enantiomeric specificity in reactions of cyclohexaamy-lose and cycloheptaamylose on, 23 233 Carboxylate ions, 32 117-118 Carboxybc acids a, 3-unsaturated, 25 109 hydrogenation of, 25 107-115 ketonization of, 24 35-37 Lewis base-promoted ruthenium catalysis, 32 389, 400... 

Hydrogen iodide in ruthenium catalysis, 32 397-400, 405 06 Hydrogen isotopes... 

Ionic models for g tensor, 32 11-14 Ionic oxides, see specific oxides Ionic promoters in ruthenium catalysis, 32 387-406... 

M(CxC) matrix, 32 290-291, 311-313 Measurements, interpretation of, in experimental catalysis, 2 251 Mechanism see also specific types cobalt catalysis, 32 342-349 dehydrocyclization, 29 279-283 rhodium catalysis, 32 369-375 ruthenium catalysis, 32 381-387 space, 32 280... 

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