Mercury acetate oxidation with

Again, as with pyridopyrimidines, the main reaction is oxidation of di- or poly-hydro derivatives to fully aromatic structures, often merely by air or oxygen. In some cases the reagent of choice is mercury(II) oxide, whilst other reagents used include sulfur, bromine, chloranil, chromium trioxide-acetic acid, hydrogen peroxide, and potassium ferricyanide, which also caused oxidative removal of a benzyl group in the transformation (306) (307)... 

Bis(2,4,6-trinitrophenyl)methane when treated with NaAc in acetic acid produced (580) as a thermostable explosive (80MIP41600). The conversion of o-nitrotoluene into 2,1-benzisoxazole was effected by mercury(II) oxide catalysis. A mercury containing intermediate was isolated and was demonstrated to be converted into 2,1-benzisoxazole (67AHC(8)277). The treatment of o-nitrotoluene derivative (581) with sulfuric acid gave (582) in 35% yield (72MI41607). 

The mercury(II) acetate oxidation of tertiary amines is frequently used to introduce unsaturation into piperidine derivatives. The iminium ion is believed to be an intermediate in this reaction. These ions can give the enamine or react further with nucleophiles to give more complex heterocycles (Scheme 4). 

The keto oximes (201 X = S, NMe) condense with ethyl acetoacetate to yield the derivatives (202) and the azaindole may be oxidized with mercury(II) acetate to the dihydro compound (203 Scheme 62) (53JCS2789). 

Acetals are usually easy to cleave by acid-catalyzed transacetalization or hydrolysis (Table 3.40). Dithioacetals, on the other hand, tend to be more resistant to hydrolysis, but cleavage can be achieved by treatment with mercury(II) salts or by oxidation with either [bis(trifluoroacetoxy)iodo]benzene [723] or periodic acid [724]. Use of the latter reagent can, however, also lead to the conversion of methyl ketones into iodo-methyl ketones [721],... 

Successive intramolecular oxypalladation of dihydroxyalkynes has been used for the synthesis of spirocyclic and bridged acetals. Equations (78) to (80) show the syntheses of some insect pheromones by this method.198 The results from several diols suggest that preferred modes for initial cyclization are 5-endo > 5-exo > 6-endo. A related conversion of 8-hydroxyoct-4-ynoic acid to an oxaspirolactone with mercury(II) oxide has been reported.199... 

Enhancement by strong acids such as TFA is a general feature of oxidations with metal acetates. Metal trifluoroacetates in TFA are much more powerful oxidants (electrophiles) than the corresponding acetates in acetic acid. Activation of the metal oxidant in TFA has been observed with co-balt(III)217 249,259,27S 276 manganese(III),237,275 lead(IV),277-281 thallium-(III),282-287 cerium(IV),288 289 and copper(II).290 Similarly, the electrophilic properties of copper(I)291 and mercury(II)292 acetates are strongly enhanced by replacement of acetate by trifluoroacetate. It has been proposed217,276 that the potent oxidizing properties of Co(III) trifluoroacetate are due to ionization to the cationic Co(III) species,... 

Dimethylaminophenyl 4-Fluorophenyl Tellnrinm Dichloride2 In a 250 ml flask fitted with a reflux condenser are placed 16.5 g (50 mmol) of 4-fluorophenyl tellurium trichloride, 19.0 g (50 mmol) of 4-dimcthylaminophenyl mercury acetate, and 100 ml of absolute dioxane. The mixture is heated under reflux for 8 h during which time it acquires a dark violet color. The mixture is allowed to cool to 20°, the precipitated mercury(II) chloride/dioxane adduct is filtered off, and activated charcoal is added to the filtrate which is then heated under reflux for 30 min. The mixture is allowed to cool and is then passed through a layer of aluminum oxide. The filtrate is concentrated to one-fourth of its original volume by distillation, the concentrate is diluted with 100 ml of hexane to precipitate the product which is filtered off, washed with hexane, dried, and recrystallized from propanol yield 7.2 g (35%) m.p. 145". 

Arnold s demonstration" that oxocarbenium ion intermediates can be formed through homobenzylic ether radical cation fragmentation reactions shows that mild oxidizing conditions can be used to prepare important reactive intermediates. Scheme 3.2 illustrates a critical observation in the development of an explanatory model that allows for the application of radical cation fragmentation reactions in complex molecule synthesis. In Arnold s seminal work, cleavage of the benzylic carbon-carbon bond in substrate 1 is promoted by 1,4-dicyanobenzene (DCB) with photoirradiation by a medium-pressure mercury vapor lamp. With methanol as the solvent, the resulting products were diphenylmethane (2) and formaldehyde dimethyl acetal (3). 

Other careful electrochemical measurements of the oxidation potentials of 2,4,6-tri-t-butylphenol and 2,6-di-t-butyl-4-methylphenol in acetate buffered ethanol or acetonitrile have been measured by Mauser et al.184). They determined the static potentials using a boron carbide indicator and a mercury/mercury-acetate reference-electrode. Since in this case the oxidation of the phenols and not the phenolates to the phenoxyls has been determined the oxidation potentials cannot be compared with those in Table 12. For other electrochemical oxidations of phenols in buffered aqueous solutions using a graphite electrode see Ref. 185 186>. 

On the basis of this and other evidence allylic mercuty(II) acetates are believed to be the reaction intermediates in all allylic oxidations with mercury(II) acetate. The isolation of the less stable secondary... 

Aliphatic nitroso compounds can be prepared from IV-alkylhydioxylamines oxidation widi bromine, chlorine or sodium hypochlorite in weakly acidic solution, reaction with potassium dichromate in acetic or sulfuric acid, and by oxidation widi yellow mercury(II) oxide in suspension in an organic solvent. Silver carbonate on Celite has also been used to prepare aliphatic nitroso compounds, such as ni-trosocyclohexane, in high yield from the corresponding hydroxylamines." Aqueous sodium periodate and tetraalkylanunonium periodates, which are soluble in organic solvents, are the reagents most commonly used for the oxidation of hydroxamic acids and IV-acylhydroxylamines to acylnitroso compounds... 

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