Silver diacetate

The formation of methylsilver and dimethylargentate has been observed in the collision-induced dissociation MS3 spectrum of silver diacetate. Dimethylargentate is stable in the gas phase, and has been isolated for short periods (10 s) without significant decomposition.10... 

Preparation of /m -3) -Acetoxypregna-5,17(20)-dien-21-aI A solution of 12.2 g of 17a-ethynylandrost-5-ene-3/ ,17jS-diol diacetate and 0.5 g of silver acetate in 250 ml acetic acid and 100 ml of acetic anhydride is refluxed under... 

The residue (12 g) which contains the 18-iodo-18,20-ether is dissolved in 200 ml of acetone, 5 g of silver chromate is added Note 3) and after cooling to 0°, 11.8 ml of a solution of 13.3 g of chromium trioxide and 11.5 ml of concentrated sulfuric acid, diluted to 50 ml with water is added during a period of 5 min. After an additional 60 min, a solution of 112 g of sodium acetate in 200 ml of water is added and the mixture diluted with benzene (400 ml), filtered and the benzene layer separated. The aqueous phase is reextracted with benzene, washed with half-saturated sodium chloride solution, dried and evaporated to yield 11.2 g of a crystalline residue. Recrystallization from ether gives 7.2 g (72%) of pure 3/5, 1 la, 20/5-trihydroxy-5a-pregnan-18-oic acid 18,20 lactone 3,11-diacetate mp 216-218°. 

The methyl substituent of 2-methyl-4,8-dihydrobenzo[l,2- 5,4-. ]dithiophene-4,8-dione 118 undergoes a number of synthetic transformations (Scheme 8), and is therefore a key intermediate for the preparation of a range of anthraquinone derivatives <1999BMC1025>. Thus, oxidation of 118 with chromium trioxide in acetic anhydride at low temperatures affords the diacetate intermediate 119 which is hydrolyzed with dilute sulfuric acid to yield the aldehyde 120. Direct oxidation of 118 to the carboxylic acid 121 proceeded in very low yield however, it can be produced efficiently by oxidation of aldehyde 120 using silver nitrate in dioxane. Reduction of aldehyde 120 with sodium borohydride in methanol gives a 90% yield of 2-hydroxymethyl derivative 122 which reacts with acetyl chloride or thionyl chloride to produce the 2-acetoxymethyl- and 2-chloromethyl-4,8-dihydrobenzo[l,2-A5,4-3 ]-dithiophene-4,8-diones 123 and 124, respectively. 

In a reaction somewhat similar to the Cr02Cl2 oxidation, Cr03 in AcOH in the presence of mineral acids produces benzylidene diacetates, which can then be hydrolyzed to the corresponding aldehydes.110,693,798 Cr(V) and Cr(IV) species were shown to be involved in the reaction.798 Silver(II) in acidic solution,845 Ce(NH3)2(N03)6,846 and photooxidation in the presence of Ti02 and Ag2S04847 are also used to accomplish aldehyde formation. 

A few diorgano tellurium hydroxide (hydrogen) sulfates are reported in the older literature. Diethyl tellurium hydroxide sulfates were claimed to have been produced from the hydroxide chloride and silver sulfate1 and from the dihydroxide and sulfuric acid2. Several ill-defined compounds that could be or could contain hydroxide hydrogen sulfates were obtained when dibenzo-l,4-oxatellurin or its 10,10-diacetate were treated with sulfuric acid3. 

The ligand was then used to form a variety of transition metal carbene complexes [207] (see Figure 3.72). Interestingly, more than one method for the formation of transition metal carbene complexes was successfully employed presence of an inorganic base (IC COj) to deprotonate the imidazolium salt and the silver(I) oxide method with subsequent carbene transfer to rhodium(I), iridium(I) and copperfi), respectively. The silver(I) and copper(I) carbene complexes were used for the cyclopropanation of styrene and indene with 1,1-ethanediol diacetate (EDA) giving very poor conversion with silver (< 5%) and qnantitative yields with copper. The diastereomeric ratio (endolexo) was more favonrable with silver than with copper giving almost a pnre diastereomer for the silver catalysed reaction of indene. 

The oxidative decarboxylation of aliphatic carboxylic acids is best achieved by treatment of the acid with LTA in benzene, in the presence of a catalytic amount of copper(II) acetate. The latter serves to trap the radical intermediate and so bring about elimination, possibly through a six-membered transition state. Primary carboxylic acids lead to terminal alkenes, indicating that carbocations are probably not involved. The reaction has been reviewed. The synthesis of an optically pure derivative of L-vinylglycine from L-aspartic acid (equation 14) is illustrative. The same transformation has also been effected with sodium persulfate and catalytic quantities of silver nitrate and copper(II) sulfate, and with the combination of iodosylbenzene diacetate and copper(II) acetate. ... 

Alkenes can be oxidized to diols by the Prevost method, which involves the reaction of an alkene with iodine and silver acetate. The frans-1,2-diacetate formed first on hydrolysis gives frans- 1,2-diols (Scheme 7.26). In the Woodward variation of the Prevost reaction, the monoester is formed under aqueous conditions, which on hydrolysis gives ds-diol. 

Acetonium ions involving the 5 a, 6 a- and i6a,i7a-positions must be invoked to explain the conversions of 3j8,5ct-diacetoxy-6/S-chlorocholestane into the 3jS,5a,6a-triol 3,6-diacetate [121] and of the i7a-acetoxy-i6ji -bromopregnan-2o-one 14) into the i6a-acetoxy"i7a hydroxypregnan 20-one 15) [122] by the action of silver acetate. Ag+-catalysed halide elimination... 

Alcohols with a hydrogen in the 8 position can be cychzed with lead tetraace-tate. ° The reaction is usually carried out at 80°C (most often in refluxing benzene), but can also be done at room temperature if the reaction mixture is irradiated with uv light. Tetrahydrofurans are formed in high yields. Little or no four- and six-membered cyclic ethers (oxetanes and tetrahydropyrans, respectively) are obtained even when y and s hydrogens are present. The reaction has also been carried out with a mixture of halogen (Br2 or I2) and a salt or oxide of silver or mercury (espe-cially HgO or AgOAc), with iodosobenzene diacetate and I2, and with ceric... 

Oxides of silver [171, 368], mercury [384], lead [431], and nitrogen [457] react at room temperature. 2,5-Hydroquinone diacetic acid and mercuric oxide in ether, after several hours at room temperature, give p-benzoquinone-2,5-diacetic acid in 90% yield [384]. 

Potassium permanganate. Dimethyl sulfide-Chlorine. Dimethyl sulfoxide. Dimethyl sulfoxide-Chlorine. Dimethylsulf-oxide Sulfur trioxide. Dipyridine chro-mium(VI) oxide. Iodine. Iodine-Potassium iodide. Iodine tris(trifluoroacetate). Iodosobenzene diacetate. Isoamyl nitrite. Lead tetraacetate. Manganese dioxide. Mercuric acetate. Mercuric oxide. Osmium tetroxide—Potassium chlorate. Ozone. Periodic acid. Pertrifluoroacetic acid. Potassium ferrate. Potassium ferricyanide. Potassium nitrosodisulfonate. Ruthenium tetroxide. Selenium dioxide. Silver carbonate. Silver carbonate-Celite. Silver nitrate. Silver oxide. Silver(II) oxide. Sodium hypochlorite. Sulfur trioxide. Thalli-um(III) nitrate. Thallium sulfate. Thalli-um(III) trifluoroacetate. Triphenyl phosphite ozonide. Triphenylphosphine dibromide. Trityl fluoroborate. 

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