Bromides from ethers

Reactions with cyclobutadieneiron tricarbonyl compds. Bromides from ethers... 

Ethers. In the presence of anhydrous agents such as ferric chloride (88), hydrogen bromide, and acid chlorides, ethers react to form esters (see Ethers). Esters can also be prepared from ethers by an oxidative process (89). With mixed sulfonic—carboxyhc anhydrides, ethers are converted to a mixture of the corresponding carboxylate and sulfonate esters (90) ... 

Although ethereal solutions of methyl lithium may be prepared by the reaction of lithium wire with either methyl iodide or methyl bromide in ether solution, the molar equivalent of lithium iodide or lithium bromide formed in these reactions remains in solution and forms, in part, a complex with the methyllithium. Certain of the ethereal solutions of methyl 1ithium currently marketed by several suppliers including Alfa Products, Morton/Thiokol, Inc., Aldrich Chemical Company, and Lithium Corporation of America, Inc., have been prepared from methyl bromide and contain a full molar equivalent of lithium bromide. In several applications such as the use of methyllithium to prepare lithium dimethyl cuprate or the use of methyllithium in 1,2-dimethyoxyethane to prepare lithium enolates from enol acetates or triraethyl silyl enol ethers, the presence of this lithium salt interferes with the titration and use of methyllithium. There is also evidence which indicates that the stereochemistry observed during addition of methyllithium to carbonyl compounds may be influenced significantly by the presence of a lithium salt in the reaction solution. For these reasons it is often desirable to have ethereal solutions... 

A mixture of 3.18 g (10 mmoles) of 17 -hydroxy-2-hydroxymethylene-5a-androstan-3-one, 20 ml dry dimethyl formamide and 0.3 g (13 mmoles) of sodium hydride is stirred for 0.5 hr at room temperature under nitrogen. A total of 1.51 g (12.5 mmoles) of redistilled allyl bromide is added and the mixture is stirred for 1 hr on the steam bath. Aqueous potassium hydroxide (2 g in 5 ml of water) is added and stirring is continued for 1 hr on the steam bath. The reaction mixture is diluted with 50 ml of methylene dichloride followed by careful addition of 300 ml of water. The organic phase is separated and the aqueous phase is again extracted with 50 ml of methylene dichloride. The combined extracts are washed with water, dried over sodium sulfate, filtered and chromatographed on 200 g of silica gel. Elution with pentane-ether (4 1) provides 2a-allyl-17j -hydroxy-5a-androstan-3-one 0.85 g (26%) mp 118-119° [aj 14° (CHCI3), after crystallization from ether-hexane. 

Ethoxyacetylene A solution of 7 g of estrone methyl ether in tetra-hydrofuran (80 ml) is slowly added with stirring to ethoxyethynylmagnesium bromide (from ethoxyacetylene, 9 g, and 3 M ethereal methyhnagnesium bromide, 32 ml) and the mixture is refluxed overnight with stirring. Aqueous... 

Dehydrochlorination of bis(tnfluoromethylthio)acetyl chloride with calcium oxide gives bis(trifluoromethylthio)ketene [5] (equation 6) Elimination of hydrogen chloride or hydrogen bromide by means of tetrabutylammonium or potassium fluoride from vinylic chlorides or bromides leads to acetylenes or allenes [6 (equation 7) Addition of dicyclohexyl-18-crown-6 ether raises the yields of potassium fluoride-promoted elimination of hydrogen bromide from (Z)-P-bromo-p-ni-trostyrene in acetonitrile from 0 to 53-71 % In dimethyl formamide, yields increase from 28-35% to 58-68%... 

Benziloyloxy-1-azabicyclo[2.2.2] octane methobromide was prepared by adding 20 cc of a 30% solution of methyl bromide in ether to a solution of 2.5 g of 3-benziloyloxy-1-azabicyclo[2.2.2] octane in 20 cc of chloroform. After standing for 3 hours at room temperature and 15 hours at -i-5°C, a crystalline precipitate had formed. This was filtered off and recrystallized from a mixture of methanol, acetone, and ether prisms melting at 240° to 241°C. 

Methyl 2-deoxy-39496-tri-0-p-nitrobenzoyl-p-T>- yxo-hexoside. A solution of 370 mg. of 2-deoxy-3,4,6-tri-0-p-nitrobenzoyl- -D-Zyxo-hexosyl bromide (5) in 15 ml. of dry dichloromethane is added to a stirred suspension of 500 mg. of silver carbonate in 100 ml. of absolute methanol. The mixture is stirred for 20 hours and filtered the silver salts are washed several times with warm dichloromethane. The combined filtrate and washings are evaporated to dryness under diminished pressure, and the residue is recrystallized five times from ether-dichloromethane, giving 61% of pure product, having m.p. 173°-174°C. and [ ]D + 36° in chloroform. 

Silver fluoborate, reaction with ethyl bromide in ether, 46, 114 Silver nitrate, complexing with phenyl-acetylene, 46, 40 Silver oxide, 46, 83 Silver thiocyanate, 45, 71 Sodium amide, in alkylation of ethyl phenylacetate w ith (2-bromo-ethyl)benzene, 47, 72 in condensation of 2,4-pentanedione and 1 bromobutane to give 2,4-nonanedione, 47, 92 Sodium 2 ammobenzenesulfinate, from reduction of 2 mtrobenzenesul-finic acid, 47, 5... 

Deacetylanisomycin (4) is synthesized using L-tartaric acid (1) as a precursor in 12% overall yield16. The key step is the diastereoselective addition of (4-methoxybenzyl)magnesium chloride to the C — N double bond of nitrone 2 at 0°C in the presence of 1 equivalent of ethylmagncsium-bromide diethyl ether complex in dichloromethane. This procedure affords a chromatograph-ically separable mixture of the hydroxylamines 3 a and 3 b in a diastereomeric ratio [(2R,35,4R)/ (25,35,47 )] 70 30 and 60% yield from 2. 

Thallium has been determined in 10 ml of ashed serum or in urine by extracting with sodium diethyldithiocarbamate into MIBK n°). More recently, Savory and co-workers 1131 described a wet digestion procedure for 50 ml of urine or 5 ml of serum in which the thallium is separated by extracting the bromide into ether, evaporating the ether and then taking up in dilute acid for aspiration. As little as 0.1 ppm is determined in urine. Curry et al.114) determined less than 1 ng of thallium in 200 /d of urine by using the tantalum sample boat technique. The sample in the boat is dried by holding the boat 1 cm from the flame and then it is inserted into the flame where it is vaporized. A similar procedure is used for >3 ng of thallium in 50-100/al of blood, except that the blood is preashed with 3 drops of nitric acid. Since the tantalum boat method is susceptible to interelement interferences, the method of standard additions is used for calibration. 

The catalysed -elimination of hydrogen bromide from 2-bromoethyl and 1,2-dibromoethyl sulphides, using 9.1.1 or 9.1.2, provides a convenient route to vinyl and alkynyl sulphides, respectively [17, 18], which, as their sulphoxides or sulphones, have considerable utility as dienophiles. Aryl vinyl ethers (>90%) have been obtained by analogous procedures from 2-chloroethyl ethers [19]. 

Stearyl bromide (5.5 mmol) and triphenylphosphine (5.8 mmol) were heated under reflux for 20 hours in 30 mL anhydrous xylene. Upon completion of the reaction (as monitored by thin-layer chromatography) the solvent was removed followed by purifying the obtained crude yellowish oil by silica gel column chromatography using methanohchloroform (5 95) as an eluent. Purified STPP, obtained as colorless oil, crystallized on standing and was recrystallized from ether to yield pure STPP in 35% to 45 /o yields. 

Elimination of hydrogen bromide from a-bromo-y-butyrolactone with triethylamine, 46,22 Epichlorohydrin, 46, 24 Ether, /-butyl phenyl, id, 89 /j-Ethoxyphenyl isothiocyanate, 46, 21 Ethyl acetoacetate, 46, 82 Ethyl benzoyloxy cyanoacetates, 46, 38 Ethyl y-BROMOBUTYRATE, 46, 42 Ethyl 2-biomocyclopentane acetate, 46, 44... 

Phenazone. Equimolar amounts of phenylhydrazine and ethyl acetoacetate are heated for 8 hours at 125°. The resulting phenyl-3-methyl-5-pyrazolone is dissolved in anisole and heated to 135°. Methyl bromide is passed through (bubbled into) the solution for 10 hours at 135°, and the anisole is removed by steam distillation. Phenazone is extracted from the remaining residue with chloroform and the chloroform is distilled or evaporated off The residue is recrystallized from ether. Mp 111-113°. Dosage 300 to 600 mg. This drug also has antipyretic action (reduces fever) and can cause rashes, nausea, and fainting. 

The gem-dibromocyclopropanes are treated with an etheral solution of either methyllithiura or n-butyllithium at 0° to — 80°C. Methyllithium is preferable to /2-butyllithium because occasionally difficulties are encountered in completely separating the n-butyl bromide from the allene product. 

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