Ether methyl

CH Ns (200 mmol). Et20 added to a suspension of the diet adsorbed onto SiQs (30 g) 

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When a solution of a diazonium compound in absolute methanol is boiled, the chief product is the corresponding methyl ether, henzenediiizonium hydrogen sulphate thus giying methyl phenyl etlier or anisole ... 

The formaldehyde may be replaced by methylal CHjlOCH,), or by chloro-methyl ether CHjOCHjCl, produced from paraformaldehyde, hydrogen chloride and methyl alcohol ... 

Naphthyl methyl ether (nerolin). Use 36 0 g. of p-naphthol, 10-5 g. of sodium hydroxide in 150 ml. of water, and add 31 -5 g. (23 -5 ml.) of dimethyl sulphate whilst the mixture is cooled in ice. Warm for 1 hour at 70-80°, and allow to cool. Filter oflF the naphthyl methyl ether at the pump, wash with 10 per cent, sodium hydroxide solution, then liberally with water, and drain thoroughly. Recrystallise from benzene or methylated spirit. The yield is 33 g., m.p. 72°. 

Ph.CH2.OMe, Ph.(CH2)2.0Me, Ph.(CH2)3.0Me (2-3, 3-4, 1-3), does not decrease steadily, but goes through a maximum. These two circumstances point to a specific -interaction in nitrations of the ethers with acetyl nitrate which is important with benzyl methyl ether, more important with methyl phenethyl ether, and not important with methyl phenpropyl ether. This interaction is the reaction with dinitrogen pentoxide already mentioned, and the variation in its importance is thought to be due to the different sizes of the rings formed in the transition states from the different ethers. 

The argtiments of Norman and his co-workers seem to give affirmative answers to the first and second of these questions, but it is doubtful if the available data further require such an answer for the third question. It can be argued that the crucial comparison made between the behaviour of benzyltrimethylammonium ion and protonated benzyl methyl ether is invalid, and that it is possible to interpret the results in terms of nitration by the nitronium ion, modified by protonation of the oxygen atom of the ether a case for the possible involvement of the nitro-nium ion in specific interaction leading to o-substitution has been made. ... 

Six protective groups for alcohols, which may be removed successively and selectively, have been listed by E.J. Corey (1972B). A hypothetical hexahydroxy compound with hydroxy groups 1 to 6 protected as (1) acetate, (2) 2,2,2-trichloroethyl carbonate, (3) benzyl ether, (4) dimethyl-t-butylsilyl ether, (5) 2-tetrahydropyranyl ether, and (6) methyl ether may be unmasked in that order by the reagents (1) KjCO, or NH, in CHjOH, (2) Zn in CHjOH or AcOH, (3) over Pd, (4) F", (5) wet acetic acid, and (6) BBrj. The groups may also be exposed to the same reagents in the order A 5, 2, 1, 3, 6. The (4-methoxyphenyl)methyl group (=MPM = p-methoxybenzyl, PMB) can be oxidized to a benzaldehyde derivative and thereby be removed at room temperature under neutral conditions (Y- Oikawa, 1982 R. Johansson, 1984 T. Fukuyama, 1985). 

The most stable protected alcohol derivatives are the methyl ethers. These are often employed in carbohydrate chemistry and can be made with dimethyl sulfate in the presence of aqueous sodium or barium hydroxides in DMF or DMSO. Simple ethers may be cleaved by treatment with BCI3 or BBr, but generally methyl ethers are too stable to be used for routine protection of alcohols. They are more useful as volatile derivatives in gas-chromatographic and mass-spectrometric analyses. So the most labile (trimethylsilyl ether) and the most stable (methyl ether) alcohol derivatives are useful in analysis, but in synthesis they can be used only in exceptional cases. In synthesis, easily accessible intermediates of medium stability are most helpful. 

The allylic geminal diacetate 141 undergoes the monoallylation of malonates to give 142 and the two regioisomers 143 and 144[93,94]. The dimethylacetal 145 or ortho esters of aromatic and a,/3-unsaturated carbonyl compounds react with trimethylsilyl cyanide to give the methyl ether of cyanohydrin[95]. 

Carbonylation of allylic alcohols requires severe conditions[248]. The carbonylation of allylic alcohols proceeds smoothly in the presence of LiCl and Ti(IV) isopropoxide[249j. The allylic methyl ether 394 can be carbonylated with the use of PdCl2[250] or 7r-allylpalladium coordinated by BF4, PF, and... 

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