Lead ruthenium oxide

The accessibility of the various oxidation states is very important in these reactions. For example, the reaction of alkenes with ruthenium(vm) oxide instead of permanganate leads to the cleavage of the C=C bond and the formation of aldehydes rather than a 1,2-diol (Fig. 9-35). 

The synthesis of telechelic oligomers by oxidative cleavage has been extensively studied by numerous authors and Cheradame [117] reviewed the main reactions leading to telechelic polymers starting from high molecular polymers. As he showed, ozonolysis remains one of the preferred method in addition to Ruthenium tetroxide oxidation to obtain a-co functional oligomers. 

Murai et al. [14] found that Ru3(CO)12 shows a high catalytic activity for the intramolecular hetero-P-K-type reaction of yne-aldehydes (Eq. 4). A variety of substituents on the acetylenic moiety can be tolerated, and the application to cyclohexane-fused bicyclic systems is also feasible. Although the mechanism of this catalysis remains elusive, two pathways have been proposed as the initial step for the reaction in Eq. (4) via the oxidative cyclization of yne-aldehydes to a ruthenium center, leading to a metallacycle 3, or via the oxidative addition of an aldehyde C-H bond to ruthenium, leading to 4. 

Fig. 20 Simple pH control in ruthenium-catalysed oxidation of ethers leading to higher activities and selectivities...

Transition metal-catalyzed cyclizations leading to formation of a new CO bond provide a particularly useful approach to dihydrofurans . For example, a high-yielding method for the synthesis of 2,3-dihydrofurans is provided by a ruthenium-catalyzed oxidative cyclization of 4-penten-l-ols (Scheme 64) <2003CL24>. 

Secondary positions tend to be more reactive towards oxidation than tertiary positions, unless steric hindrance (Uctates otherwise. Good examples of this are the chromic acid oxidation of the ether (12)4 and the ruthenium tetroxide oxidation of the ether (13), both of which lead to lactone formation (Scheme 2). Oxidation of the quassinoid intermediate (14), on the other hand, is completely nonselective (equation 15). ... 

A successful ruthenium-catalyzed oxidative coupling and subsequent cyclization between 2-aminobenzyl alcohol and secondary alcohols in the presence of KOH and 1-dodecene leading to quinolines has been reported <03T7997>. After optimization of conditions, yields were fair to good. The reaction is widely applicable to a large series of 2-substituted quinolines. 

PbO , Lead oxide solid solns. with ruthenium oxide (RujOj), pyrochlore, 22 69... 

RU2O3, Ruthenium oxide, solid solns. with lead oxide Pb02, pyrochlore, 22 69 RU2O3C14H12, Ruthenium, p-carbonyl-p.-methylene-bis[carbonyl(it -cyclopen-tadienyl)-, 25 182... 

Oxidation of a cyanohydrin derived from a conjugated aldehyde (as the 0-TMS derivative) using py-ridinium dichromate (PE)C) in DMF gave an a,3-unsaturated lactone (5 -butenolide) as the major product (equation 12). Simple nonconjugated cyanohydrins are not satisfactory substrates for the synthesis of acyl cyanides using PDC, because they seem to add to the initially formed acyl cyanides, leading ultimately to cyanohydrin esters. Oxidation of cyanohydrin to acyl cyanides can be carried out either by means of manganese dioxide, ruthenium-catdyzed oxidation with t-butyl hydroperoxide or NBS. ... 

Ruthenium pyrochlore oxides, mixed oxides of ruthenium and bismuth or lead with the general formula A2+xRu2.x07.y (A = Pb or Bi 0 < x < 1 0 < y < 0.5) catalyze the oxidative cleavage of vic-diols to the corresponding... 

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