Ruthenium tetroxide, oxidations with

A solution of 2.4 g (0.012 mol) of ethyl l-acetylpiperidine-2-carboxylate in 40 mL of ethyl acetate is added to a mixture of 0.240 g of hydrated ruthenium dioxide and 120 mL of 10% aqueous solution of sodium periodate (0.056 mol). The mixture is vigorously stirred at room temperature for 14 h. The organic layer is separated, the aqueous layer is extracted with three 40-mL portions of ethyl acetate, and the combined organic solutions are stirred with 2 mL of isopropyl alcohol for 2-3 h to destroy the excess of ruthenium tetroxide. The black ruthenium dioxide that precipitates from the solution is filtered, and the filtrate is washed with 40 mL of water, dried with anhydrous sodium sulfate, and evaporated in vacuo to give 2.42 g (95%) of crude ethyl l-acetyl-6-oxopiperidine-2-carboxylate. 

All operations should be done in th,e hood, because ruthenium tetroxide possesses an unpleasant ozone-lik smell. Commercially available ruthenium dioxide may differ in its properties, especially,in its reaction with sodium periodate, depending on the way it is prepared and on the content of water in its hydrated form [1207], 

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Oxidation of a mixture of perfluorononene isomers to a mixture of per-fluorocarboxylic acids is accomplished with two agents, potassium permanganate and ruthenium tetroxide. Oxidation with potassium permanganate is slower and gives lower yields than oxidation with ruthenium tetroxide [40] (equation 32). 

When n = 0 or 1, the system appeared to be too rigid to allow the radical pair created upon hydrogen abstraction to form a carbon-carbon bond. Hence a considerable amount of chlorine appears in the product from radical abstraction from the solvent, carbon tetrachloride. When n = 2 the radicals are able to form a carbon-carbon bond. After a five-step workup of the crude irradiation product including reduction with LiAlH4, acetylation, dehydration, oxidation with ruthenium tetroxide, and hydrolysis a 16% yield of previously unreported 12-keto-3a-chlorestanol was obtained. However,... 

Pseudo-cc-DL-allopyranose (61) has been prepared from 54 by epimerization of the C-3 configuration as follows. O-Isopropylidenation of 54 with 2,2-dimethoxypropane gave l,2 4,6-di-0-isopropylidene-pseudo-a-DL-glucopyranose (56). On oxidation with ruthenium tetroxide and sodium metaperiodate, 56 gave the 3-oxo derivative (57), which was converted into l,2 4,6-di-0-isopropylidene-pseudo-a-DL-allopyranose (58) exclusively by catalytic hydrogenation under the presence of Raney nickel. Conven-. tional acetylation of 58 furnished the 3-O-acetyl derivative (59). Hydrolysis of 59 with aqueous acetic acid, followed by acetylation afforded pseudo-a-DL-allopyranose pentaacetate (60), which gave the free pseudo-sugar 61 on usual alkaline hydrolysis [22] (Scheme 13). 

Deacetylation of 80 in methanolic sodium methoxide and successive O-isopropyli-denation with 2,2-dimethoxypropane gave 2-0-acetyl-3,4-O-isopropylidene-l,6-an-hydro-pseudo-p-DL-galactopyranose (81), after acetylation. Removal of the acetyl group of 81, followed by oxidation with ruthenium tetroxide and sodium metaperiodate afforded the 2-oxo derivative (82). Catalytic hydrogenation of 82 under the presence of platinum catalyst and acetolysis in a mixture of acetic acid, acetic anhydride and sulfuric acid gave pseudo-P-DL-talopyranose pentaacetate (83) [25] (Scheme 17). 

Oxidation with ruthenium tetroxide was also used on N-acyl and N-ethoxycarbonyl heterocyclic enamines87 (Scheme 64). 

Sodium periodate (sodium metaperiodate), NaI04 (mp 300 °C dec), which is commercially available, is applied mainly in aqueous or aqueous-alcoholic solutions. Like the free periodic acid, sodium periodate cleaves vicinal diols to carbonyl compounds [762], This reaction is especially useful in connection with potassium permanganate [763, 764] or osmium tetroxide [765], Such mixed oxidants oxidize alkenes to carbonyl compounds or carboxylic acids, evidently by way of vicinal diols as intermediates. Sulfides are transformed by sodium periodate into sulfoxides [322, 323, 766, 767, 768, 769, 770, 771, 772], and selenides are converted into selenoxides [773]. Sodium periodate is also a reoxidant of lower valency ruthenium in oxidations with ruthenium tetroxide [567, 774],... 

CC14, HOAc, Ac20). The lactone (2) was also obtained to some extent by oxidation with ruthenium tetroxide, but extensive side reactions were also noted.1... 

S223). G. y-3,6-piperidazinedicarboxylic acid 116 could be prepared from the adduct 114 which was oxidized with ruthenium tetroxide at 0°C to give, after esterification, the ester 115. Hydrolysis of the latter afforded 116 (95CPB535). 

Compound (265) was synthesized from piperidine ethanol with thionyl chloride in the presence of pyridine. Subsequent oxidation with ruthenium tetroxide gave the S,S-dioxide derivative <90TA885>. 

Scheme 25. Possible sites for oxidation with ruthenium tetroxide (7) Oxidation of sulfide to sulfoxide or sulfone [140].

Oxidations with ruthenium tetroxide Lactones from cyclic ethers s. lA, 221 RuOi CHa -V CO... 

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