Anhydrous hydrogen peroxide in ether

Trialkyltin methoxides react with anhydrous hydrogen peroxide in ether to give the rather unstable bis(trialkyltin) peroxides, RsSnOOSnRs (214). Under the same conditions, dialkyltin dimethox-ides give polymeric peroxides, (RzSnOO), but, if an aldehyde is present, monomeric peroxides of the following structure are obtained (215). 

A solution of anhydrous hydrogen peroxide in ether ( 2.5 M) is obtained by repeated extraction of 30% aqueous hydrogen peroxide with ether and drying of the ether extracts over anhydrous magnesium sulfate. The hydrogen peroxide content is determined by iodometric titration [726]. 

Because osmium tetroxide is expensive, and its vapors are toxic, alternate methods have been explored for effecting vic-glycol formation. In the aliphatic series, olefins can be hydroxylated with hydrogen peroxide with the use of only a catalytic amount of osmium tetroxide. Anhydrous conditions are not necessary 30% hydrogen peroxide in acetone or acetone-ether is satisfactory. The intermediate osmate ester is presumably cleaved by peroxide to the glycol with regeneration of osmium tetroxide. When this reaction was tried on a A -steroid, the product isolated was the 20-ketone ... 

I-Alkoxyhydroperoxides. Rieche and Bischoff preffared anhydrous hydrogen peroxide by treating a solution of 60 g. of 84% peroxide in ether with anhydrous sodium sulfate and magnesium carbonate. After 2 days the mixture was filtered and an aliquot titrated. One equivalent of an acetal was added to 1 equivalent of the ethereal solution, and the mixture was heated cautiously at 70°. The ether was allowed to distil to give a mixture of the acetal and the anhydrous reagent. After a reaction period of about 15 hrs. at 70°, the 1-alkoxyhydroperoxide was isolated in yields in the range 40-70%. 

Alkylborinic esters, obtained from alkylboronic esters and an organometallic reagent, are converted into the corresponding ketones by the reaction with dichloromethyl methyl ether in the presence of a hindered base, followed by oxidation with hydrogen peroxide in pH 8 buffer or with anhydrous trimethylamine Ar-oxide18. 

A soln. of N-isopropylidenecycIohexylamine in anhydrous ether mixed with a soln. of hydrogen peroxide in the same solvent cyclohexyl-a-hydroperoxy-isopropylamine. Y 80%. F. e. s. E. Hoft and A. Rieche, Ang. Gh. 77, 548 (1965). 

A 500-ml, three-necked, round-bottom flask is fitted with a mechanical stirrer, a thermometer, and a wide-stern (powder) funnel. The flask is cooled in an ice-salt bath and charged with 125 ml (approx. 0.5 mole) of 15% sodium hydroxide solution. When the stirred solution reaches -10°, 30% hydrogen peroxide (57.5 g, 52.5 ml, approx. 0.5 mole) previously cooled to -10° is added in one portion. The pot temperature rises and is allowed to return to —10° whereupon 37.5 g (0.25 mole) of phthalic anhydride (pulverized) is added rapidly with vigorous stirring. Immediately upon dissolution of the anhydride, 125 ml (approx. 0.25 mole) of cooled (-10°) 20% sulfuric acid is added in one portion. (The time interval between dissolution of the anhydride and the addition of the cold sulfuric acid should be minimized.) The solution is filtered through Pyrex wool and extracted with ether (one 250-ml portion followed by three 125-ml portions). The combined ethereal extracts are washed three times with 75-ml portions of 40% aqueous ammonium sulfate and dried over 25 g of anhydrous sodium sulfate for 24 hours under refrigeration. 

It is believed that the regiospecifidty of the dioxabicyclization and the concurrent formation of bicyclic ethers 48 and 49 both result from equilibrium control of reversible (per)oxymercuration — de(per)oxymercuration. Thus to optimise the yield of 47 it is important to minimize the amount of water present in the reaction mixture and use of concentrated hydrogen peroxide (>80%) with anhydrous mercury(II) trifluoroacetate is recommended. 

C. Excess 1 is destroyed by adding 22 mL (0.3 mol) of freshly distilled propionaldehyde and stirring for 1 hr at room temperature. Liberated a-pinene is then removed by vacuum (Note 7). Tetrahydrofuran, 200 mL, is added, followed by 150 mL of 3 M aqueous NaOH. Hydrogen peroxide (150 mL, 30%) is added dropwise (CAUTION Note 8). Oxidation is complete in 3 hr at 40°C. The reaction mixture is transferred to a separatory funnel and extracted with three 50-mL portions of ethyl ether. The ether layers are combined and dried with copious amounts of anhydrous magnesium sulfate, filtered, and concentrated by rotary evaporation to give an oil. Distillation at 60-65°C (3.0 mm) yields 31 g (0.245 mol) of l-octyn-3-ol, 86% yield (Note 9). The distillation pot residue is a thick oil consisting for the most part of cis-l,5-cyclo-octanediol. An NMR lanthanide shift study showed the alcohol to be 93% (R) and 7% (S), 86% ee, (Note 10 and 11). 

A 500-ml Erlenmeyer flask was charged withl,5-dioxa-9-aza-8,8,10,10-tetramethyl-spiro [5,5]-undecane (0.04 mole) dissolved in 150 ml of methanol and then treated with 40 ml of 35% aqueous hydrogen peroxide followed by sodium tungstate dehydrate (0.4 g). The mixture was left for 3 days at ambient temperature where after one day the color became dark orange. It was then extracted with three 50-mI portions of t-butyl methyl ether and dried with an anhydrous Na2S04. The solution was concentrated, and... 

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