Iodomethyl methyl ether

Methyl ethers can be cleaved in minutes at room temperature with di-iodomethyl methyl ether.90... 

Orthoesters are converted into esters with TMS-I. The dimethyl acetal of formaldehyde, methylal, affords iodomethyl methyl ether in good yield (eq 12) 7a (in presence of alcohols, MOM ethers are formed). 7b a-Acyloxy ethers also furnish the iodo ethers, e.g. the protected 8-acetyl ribofuranoside gave the a-iodide which was used in the synthesis of various nucleosides in good yield (eq 13). Aminals are similarly converted into immonium salts, e.g. Eschenmoser s reagent, Dimethyl(methylene)ammonium Iodide, in good yield. ... 

Denmark et al. studied the effect of zinc iodide on the catalytic, enantioselective cyclopropanation of allylic alcohols with bis(iodomethyl)-zinc as the reagent and a bismethanesulfonamide as the catalyst 17]. They found significant rate enhancement and an increased enantiomeric excess of the product cyclopropane upon addition of 1 equivalent zinc iodide. Their studies and spectroscopic investigations showed that the Schlenk equilibrium appears to lie far on the left (IZnCHjI). Charette et al. used low temperature - C-NMR spectroscopy to differentiate several zinc-carbenoid species [18]. They also found evidence that in the presence of zinc iodide, bis(iodomethyl)zinc is rapidly converted to (io-domethyOzinc iodide. Solid-state structures of (halomethyl)zinc species have been described by Denmark for a bis(iodomethyl)zinc ether complex (6a) [19] and Charette for an (iodo-methyl)zinc iodide as a complex with 18-crown-6 (6b) [20] (Fig. 2). 

Protection of primary hydroxyl groups. Sodium alkoxides (from sodium hydride) react with iodomethyl methyl sulfide at 0° in DME to form methyl-thiomethyl ethers (MTM ethers) in yields usually >86%. These ethers are stable to bases and nucleophiles (NaH, RLi, NaOR) and fairly stable to acid. Thus acetonide and THP protecting groups can be cleaved more easUy by acid than the MTM ether function. 

B Add 30 g (II) over one-half hour to 420 ml methyl iodide and let stand fifteen hours at 5°. Separate the iodomethylate which precipitates, dry briefly at 50° and heat with vigorous stirring at 80° for two hours with 60 g NaCN in 1 L water. Extract with CHC13, dry and evaporate in vacuum the extract and dissolve the residue in 250 ml ether. Filter, evaporate in vacuum to a few ml and precipitate the acetonitrile (III) by adding petroleum ether. The acetonitrile can also be prepared directly from the indole via the Grignard reagent as given elsewhere here. 

A mixture of 7-[(Z)-2-ethoxyimino-2-(2-tritylaminothiazol-4-yl)acetamido]-3-iodomethyl-3-cephem-4-carboxilate (4.5 g, 4.83 mmoles) and N-methylpyrrolidine (0.65 ml, 6.28 mmoles) in CH2CI2 (45 ml) was stirred at room temperature for 20 min. Ether (300 ml) was added to the mixture to separate the quaternary salt of the blocked cephalosporin, which was collected by filtration and treated with 90% trifluoroacetic acid (TFA) (40 ml) at room temperature for 1 hour. The mixture was then evaporated under reduced pressure below 20°C. The residue was triturated with ether to give the TFA salt of 7-[(Z)-2-methoxyimino-2-(2-aminothiazol-4-yl)acetamido]-3-[(l-methyl-l-pyrrolidinium)methyl]-3-cephem-4-carboxylate (2.40 g), which was dissolved in methanol (5 ml) and treated with 1 M solution of sodium-2-ethylhexoate in ethyl acetate (8 ml) at room temperature for 30 min. After the addition of ethyl acetate (100 ml), the precipitate (1.94 g) formed was collected by filtration. HPLC analysis showed that the crude product was 7% pure with a 1 8 ratio of the S3 isomer to the S2 isomer. Purification of the product by HPLC was repeated three times (Lichrosorb RP-18, eluted with 5% aqueous methanol or 0.01 M ammonium phosphate buffer (pH 7.2 containing 5% of methanol) to give 35 mg (1.5%) of the title product as a colorless powder of 7-[(Z)-2-methoxyimino-2-(2-aminothiazol-4-yl)acetamido]-3-[(l-methyl-l-pyrrolidinium)methyl]-3-cephem-4-carboxylate. Estimated purity (by HPLC) 90%. M.p. 150°C (dec.). 

Emschwiller first presented evidence for the formation of iodomethyl-zinc iodide (I) by the reaction of methylene iodide with zinc-copper couple in ether 124). An ether solution of (I) gives methylene iodide and methyl iodide when treated with iodine and water, respectively, and evolves a considerable amount of ethylene when heated at prolonged... 

Dinitro Methyl Anisole (4-Nitro-2-nitromethyl anisole, 3-Nitro-6-methoxynitromethyl toluol or Methyl-[5-nitro-2-nitromethylphenyl] -ether). CH3.0.(N02X 6H3.CH2N02, mw 212.18, N 13.21%, OB to CO2 —113.11%, cryst, mp 93—94°. Prepd from 4-nitro-2(iodomethyl) anisole in ether-benzene soln by treatment for 3 days at RT with Ag nitrate. The sodium salt explodes violently on heatii ... 

The alkaloid Syphilobin F,a2-substituted-3-pyridinol(see Section VI., p. 861), is 0-methylated by diazomethane in diethyl ether-benzene in 43% yield. Anhydro-3-hydroxy-N-roethylpyridiniumhydroxide (XII-S67) can be formed by the reaction between 3-pyridinol and diazomethane, by the reaction of Mmethyl-3-hydroxypyridinium chloride with anhydrous sodium carbonate and by thermal decomposition of 3-methoxypyridine iodomethylate. However, its preparation from the dimer complex of Mmethyl-3-hydroxypyridinium iodide (XII-S68) by treatment with silver oxide was the most convenient method. It has also been prepared from the quaternary iodide. ... 

Preparative Methods several methods for the preparation of bis[(trimethylsilyl)methyl]zinc have been reported. Addition of powdered anhydrous zinc(II) chloride to a solution of [(trimethylsilyl)methyl]magnesium chloride in diethyl ether at 0 °C and subsequent stirring for 4 days at room temperature affords the title compound in 90% yield after fractional distillation. A second route consists of the reaction of (iodomethyl)tri-methylsilane with zinc/copper couple (prepared by reduction of CuO with dihydrogen in the presence of zinc dust) at reflux for 3 h and affords the title compound in 56% yield. Bis[(trimethylsilyl)methyl]zinc can also be prepared quantitatively by reacting bis[(trimethylsilyl)methyl]mercury with an excess of zinc at ambient conditions. ... 

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