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With osmium

Another method for the hydroxylation of the etliylenic linkage consists in treatment of the alkene with osmium tetroxide in an inert solvent (ether or dioxan) at room temperature for several days an osmic ester is formed which either precipitates from the reaction mixture or may be isolated by evaporation of the solvent. Hydrolysis of the osmic ester in a reducing medium (in the presence of alkaline formaldehyde or of aqueous-alcoholic sodium sulphite) gives the 1 2-glycol and osmium. The glycol has the cis structure it is probably derived from the cyclic osmic ester ... [Pg.894]

The element forms an alloy with osmium which is used for tipping pens and compass bearings. [Pg.139]

With osmium tetroxide catalyst [PLATINUM-GROUP METALS, COMPOUNDS] (Vol 19)... [Pg.193]

CARBON - CARBON AND ARTIFICIALGRAPHITE - APPLICATIONS OF BAKED AND GRAPHITIZED CARBON] (Vol 4) -With osmium tetroxide catalyst [PLATINUM-GROUP METALS, COMPOUNDS] (Vol 19)... [Pg.193]

Fig. 1. Transmission electron micrograph of ABS produced by an emulsion process. Staining of the mbber bonds with osmium tetroxide provides contrast... Fig. 1. Transmission electron micrograph of ABS produced by an emulsion process. Staining of the mbber bonds with osmium tetroxide provides contrast...
Cyclodecanediol has been prepared by the hydrogenation of sebacoin in the presence of Raney nickel or platinum, by the reduction of sebacoin with aluminum isopropoxide or lithium aluminum hydride, and by the oxidation of cyclodecene with osmium tetroxide and pyridine. ... [Pg.13]

A classical method for the vicinal hydroxylation of a double bond involves treatment with osmium tetroxide to give a cyclic ester, followed by reductive cleavage to the glycol ... [Pg.183]

Many of the reactions already discussed for the preparation of bis-oxygenated pregnanes can also be used for the synthesis of 17,20,21-tris-oxygenated pregnanes by proper choice of substrate. Thus, reaction of a 17-vinyl-17-hydroxy steroid or a A -21-hydroxypregnene with osmium tetroxide will give the 17,20,21-triol, and the Stork reaction can be applied to 17a-hydroxy-20-keto steroids. [Pg.217]

One reaction touched upon briefly in an earlier discussion is the hydroxyla-tion of a A -20-cyano steroid with osmium tetroxide. When a 21-acetoxyl group is also present, the important dihydroxyacetone side-chain is obtained ... [Pg.217]

Because the unsaturated nitrile does not react with osmium tetroxide as rapidly as a simple A holefin, selectivity between other unsaturated centers is difficult to achieve. [Pg.218]

Since electronegative groups at C-20 or C-21 deactivate a A hdouble bond towards attack by osmium tetroxide, Swiss workers have devised procedures wherein these groups are first reduced with lithium aluminum hydride, and the resulting aluminum complexes are then treated with osmium tetroxide... [Pg.218]

Selective hydroxylation with osmium tetroxide (one equivalent in ether-pyridine at 0 ) converts (27) to a solid mixture of stereoisomeric diols (28a) which can be converted to the corresponding secondary monotoluene-sulfonate (28b) by treatment with /7-toluenesulfonyl chloride in methylene dichloride-pyridine and then by pinacol rearrangement in tetrahydrofuran-lithium perchlorate -calcium carbonate into the unconjugated cyclohepte-none (29) in 41-48 % over-all yield from (27). Mild acid-catalyzed hydrolysis of the ketal-ketone (29) removes the ketal more drastic conditions by heating at 100° in 2 hydrochloric acid for 24 hr gives the conjugated diketone (30). [Pg.364]

Another important reaction associated with the name of Sharpless is the so-called Sharpless dihydroxylation i.e. the asymmetric dihydroxylation of alkenes upon treatment with osmium tetroxide in the presence of a cinchona alkaloid, such as dihydroquinine, dihydroquinidine or derivatives thereof, as the chiral ligand. This reaction is of wide applicability for the enantioselective dihydroxylation of alkenes, since it does not require additional functional groups in the substrate molecule ... [Pg.256]


See other pages where With osmium is mentioned: [Pg.128]    [Pg.397]    [Pg.492]    [Pg.625]    [Pg.178]    [Pg.179]    [Pg.377]    [Pg.424]    [Pg.425]    [Pg.1113]    [Pg.168]    [Pg.5]    [Pg.89]   


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1-Vinylimidazole, complexes with osmium

2- pyridine, reaction with osmium carbonyls

2-Methylimidazole, complexes with osmium

3- Methyl-2-chlorobenzothiazolium tetrafluoroborate, reaction with osmium

3- Methyl-2-chlorobenzothiazolium tetrafluoroborate, reaction with osmium carbonyls

8-Aminoquinoline reaction with osmium complexes

Alkenes, dihydroxylation, with osmium tetroxide

Benzimidazole, calculated infrared spectra reaction with chromium and osmium

Biimidazole, as chelators reaction with osmium complexes

Carbene complexes with osmium porphyrin

Carbon monoxide, reaction with osmium complexes

Complex with carbonyl osmium

Complexes with osmium compounds

Cycloadditions of alkenes with osmium tetroxide

Dihydroxylation , of alkenes, with osmium tetroxide

Heat-Assisted Fixation with Osmium Tetroxide

Hydroxylation with osmium tetroxide

Hydroxylations with osmium tetroxide

Manganese with osmium

Metal Clusters of Iridium with Ruthenium and Osmium

Nitrido compounds, with osmium

Osmium 6]2+, reaction with acetone

Osmium asymmetric dihydroxylation with

Osmium carbonyl clusters reaction with base

Osmium carbonyl clusters with alkynes

Osmium catalysis addition with

Osmium complexes dihydroxylation with

Osmium complexes with olefins

Osmium complexes with silyl ligands

Osmium complexes, reaction with pyridines

Osmium coordinatively unsaturated, reactions with

Osmium r-alkylimides reactions with alkenes

Osmium reaction with carbon monoxide

Osmium reaction with isonitriles

Osmium reactions with

Osmium reactions with electrophiles

Osmium reactions with halogens

Osmium reactions with nucleophiles

Osmium reactions with substrate complexes

Osmium tetraoxide hydroxylation with

Osmium tetroxide mixture with sodium periodate

Osmium tetroxide reaction with alkenes

Osmium tetroxide with chlorates

Osmium tetroxide with hydrogen peroxide

Osmium tetroxide, reaction with

Osmium tetroxide, reaction with toxicity

Osmium tetroxide. reaction with alkenes toxicity

Osmium thiophene, reactions with

Osmium with acetylenes

Osmium with nickel

Osmium with nucleophiles

Osmium with phosphines

Osmium with tungsten

Osmium, electrophilic addition with

Oxidation with osmium tetraoxide

Oxidation with osmium tetroxide

Pyridines with osmium carbenes

Rhenium compounds with osmium

Silicon complexes with osmium

Tellurophene reaction with osmium complexes

Vicinal Syn Dihydroxylation with Osmium Tetroxide

With osmium carbene complexes

With osmium dihydrogen complexes

With osmium hydride complexes

With osmium synthesis

With osmium tetraoxide

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