Methoxy methyl ether cleavage

Deprotection of MEM and MOM ethers. Methoxyethoxymethyl and methoxy-methyl ethers are cleaved to the alcohol by this reagent in high yields. Either 2-butanone or 2-methyl-2-propanol is recommended as solvent. The procedure is particularly useful for cleavage of ethers of allylic alcohols, for which ZnBr, and TiCh are not useful. 

In the reaction of 10b with piperidine in DMF, a novel methyl ether cleavage reaction of the 1-methoxy group occurs in addition to the nucleophilic substitution reaction, resulting in the formation of l-hydroxy-6-nitroindole-3-carbaldehyde (5a, 10%) and 2-piperidinyl product (109, 59%, Scheme 15) [11]. 

Acid catalyzed cleavage of aromatic methyl or ethyl ethers Quantitative methoxy group determination Also ether cleavage with tnmethylsilyl Iodide ... 

Homoallyl ethers or sulfides.1 gem-Methoxy(phenylthio)alkanes (2), prepared by reaction of 1 with alkyl halides, react with allyltributyltin compounds in the presence of a Lewis acid to form either homoallyl methyl ethers or homoallyl phenyl sulfides. Use of BF3 etherate results in selective cleavage of the phenylthio group to provide homoallyl ethers, whereas TiCl effects cleavage of the methoxy group with formation of homoallyl sulfides. 

It was found possible to measure the kinetics of cleavage of protonated sec-butyl methyl ether 24 by following the disappearance of the methoxy doublet in the NMR spectrum with simultaneous formation of protonated methanol and ferf-butyl cation. The cleavage shows pseudo-first-order kinetics. Presumably, the rate-determining step is the formation of sec-butyl cation followed by rapid rearrangement to the more stable ferf-butyl cation... 

The addition of methanol to alpha-pinene in the presence of the above mentioned beta zeolite as catalyst in the batch reactor results in the cleavage of the cyclobutane ring and yields l-methyl-4-[alpha-methoxy-isopropyl]-l-cyclohexene (alpha-terpinyl methyl ether) as the main reaction product. The most common by-products to be found are isomerization compounds like camphene, limonene and terpinolene, and several bicyclic and double addition products, e.g. endo- or exo-methylbomylether, endo- or exo-methylfenchylether and cis- or trans-1,8-dimethoxy-p-menthane. 

Demelhylation of aryl methyl ethers. This cleavage can be carried out with NaCN in DMSO at 125-180° for 1-24 hours. DMSO cannot be replaced by DMF. Yields are 45-90%. The method is particularly useful for aromatic methoxy nitriles. 

Many CuO-NaOH oxidation studies for lignin and humic acids show that copper oxide does not affect cleavage of phenyl methyl ether. However, we have found that about 50% of methoxy groups are cleaved under various conditions see Table V). 

Acid catalyzed cleavage ot aromatic methyl or ethyl ethers. Quantitative methoxy group determination. Also ether cleavage with trimethylsilyl iodide.6... 

O-demethylation of aryl methyl ethers of nonphenolic aporphine alkaloids. Regioselective demethylation by this method occurs at positions 1,8, and 11 of the aporphine nucleus methylenedioxy functions survive the reaction (447). Selective cleavage of the methylenedioxy group in O-methyl-bulbocapnine with boron trichloride is discussed in Section III,C (448). The ether cleavage of methoxy- and methylenedioxy-substituted isoquinoline has been reviewed (346). 

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