Ruthenium catalysis oxidation

Under ruthenium catalysis, oxidative coupling of a,a-disubstituted benzy-lamines with acrylates can be performed efficiently at room temperature to produce (isoindol-l-yl)acetic acid derivatives (Eq. (7.48)) [58]. The reaction takes place accompanied by free amino group-directed orffio-alkenylation and successive intramolecular cyclization. 

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

The most important discoveries in ruthenium catalysis are highlighted and innovative activation processes, some of which are still controversial, are presented in this volume. They illustrate the usefulness in organic synthesis of specific reactions including carbocyclization, cyclopropanation, olefin metathesis, carbonylation, oxidation, transformation of silicon containing substrates, and show novel reactions operating via vinylidene intermediates, radical processes, inert bonds activation as well as catalysis in water. 

Carbohydrate oxidations are generally performed with dioxygen in the presence of heterogeneous catalysts, such as Pd/C or Pt/C [230]. An example of homogeneous catalysis is the ruthenium-catalyzed oxidative cleavage of protected mannitol with hypochlorite (Fig. 4.77) [231]. 

Ruthenium catalysis allows dihydroxylation providing an easy access to syn-diols, but over-oxidation is a common side reaction. The improved protocol for the Ru-catalyzed syn-dihydroxylation uses only 0.5 mol% catalyst under acidic conditions that gave products in high yields with only minor formation of side products. ... 

Figure 3. Mechanisms of Ruthenium Porphyrin Oxidation Catalysis...

A protocol for cross-dehydrogenative oxidative coupling of the 2-arylpyridine 4 with the cycloalkane 5 under ruthenium catalysis was elegantly developed by Li and... 

Scheme 1.16. Mechanisms of ruthenium porphyrin oxidation catalysis.

Oxidation of xylitol and glucitol by alkaline hexacyanoferrate-(III) under ruthenlum(VIII) catalysis is believed to proceed by an activated polyol-ruthenium(VIII) oxide complex which slowly dis-proportionates to yield ruthenium(VIII) hydride, itself being re-oxidized to the oxide. 

Jn a potentially far reaching application for melt catalysis by the transition metals, we at Texaco have demonstrated the synthesis of a range of commodity chemicals and fuels directly from CO/H2 via the use of ruthenium-containing molten salt catalysis. Products include ethylene glycol, Ci-C4 alcohols, acetic acid, acetate esters, C2+ olefins and vicinal glycol esters. In its simplest form, this new class of melt catalyst comprises one or more ruthenium sources, e.g. ruthenium carbonyls, oxides, complexes, etc. dispersed in a low-melting (m.p. <150 C) quaternary phosphonium or ammonium salt (e.g. tetrabutylphos-phonium bromide). The key components are selected such that ... 

Scheme 7.44 Domino oxidation-Michael-intramolecular alkylation reaction, domino oxidation-Michael-hemiacetalisation reaction, and domino oxidation-oxa-Michael-Michael reaction catalysed by chiral amine catalysis and ruthenium catalysis.

Alkyl hydroperoxides oxidize some sugar alcohols to the corresponding ketones under molybdenum-salt catalysis. Ruthenium tetroxide oxidizes secondary alcohols to ketones in neutral or basic media permitting, under the latter conditions, direct conversion of y-lactones into y-ketoacids. ... 

Su et al. reported the annulation of A -phenylmethacrylamide (98) with 2c using [Cp RhCl2]2 and Cu(OAc)2-H20 as catalyst and oxidant, respectively, to produce 2-pyridone derivative 99 (Scheme 25.48) [42], The same reaction can be conducted under ruthenium catalysis [43]. 

Two mechanistic pathways, which differed in the way of ruthenium-mediated initial cleavage of formyl C-H or amido N-H bond, were proposed for the catalytic cycle. As shown in Scheme 7.3, an irreversibly cleavage of formyl C-H bond by the active ruthenium complex was followed by reversible insertion of the olefin into the Ru-H bond, which afforded either six-membered or seven-membered ruthenacycle. After reductive elimination, indolin-2-ones or 3,4-dihydroquinolin-2-one was formed. According to isotopic studies, pathway leading to six-membered lactams is postulated to be less favored. Another cyclization process initiated by Ru-catalyzed oxidative addition of formyl N-H bond (Scheme 7.4) was similar to Carreira s proposal for their hydrocarbamoyla-tion reaction of allylic formamides under similar ruthenium catalysis conditions [7]. The 6-endo cyclization process is proposed to be favored under the catalytic system B. 

Aryl and heteroaryl amidines underwent oxidative C-H bond functionalization with alkynes with the aid of ruthenium catalysis [48]. In the presence of [RuCl2(p-cymene)]2/KPF5 as catalyst, the cyclization reactions led to the formation of a variety of 1-iminoisoindolines with high site selectivity, regioselectivity, and... 

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