Methoxymethyl hydroxyl protective group

Related oxidants that have been exploited to similar ends include l-(tert-butoxy)-l,2-benzoiodoxol-3(l//)-one292 and sodium bromate.293 Oxidation of benzyl ethers by l-(/erf-butoxy)-l,2-benzoiodoxol-3(l/f)-one followed by easy basic hydrolysis of the resultant benzoate ester provides a convenient alternative to the usual reductive deprotection. The reaction is carried out in the presence of alkali metal carbonates and the conditions are mild enough to be compatible with other hydroxyl protecting groups such as methoxymethyl, tetrahydropyranyl, TBS and acetate. 

Mono-hydroxyl protecting acetals, mainly methoxymethyl (MOM), benzyloxymethyl (BOM) and tetrahydropyranyl (THP) groups, have only been used sporadically in oligosaccharide chemistry, and their use will probably decrease due to the expected carcinogenicity of the used reagents (MOM-Cl and BOM-Cl) or the resulting diastereomeric mixtures (THP-acetals). 

Methoxymethyl ethers protection of the hydroxyl groups was carried out by reaction of 89 with dimethoxymethane in the presence of P2O5. Deprotection of the W-benzyl group from 90 by hydrogenation in the presence... 

The construction of the five contiguous stereocenters required for a synthesis of compound 3 is now complete you will note that all of the substituents in compound 5 are positioned correctly with respect to the carbon backbone. From intermediate 5, the completion of the synthesis of the left-wing sector 3 requires only a few functional group manipulations. Selective protection of the primary hydroxyl group in 5 as the corresponding methoxymethyl (MOM) ether, followed by benzylation of the remaining secondary hydroxyl, provides intermediate 30 in 68 % overall yield. It was anticipated all along that the furan nucleus could serve as a stable substi-... 

Hydroxyl groups protected as acetonides or as silyl, tetrahydropyranyl, benzyl, or methoxymethyl ethers are stable to these conditions. Yields with KMn04 are higher than those obtained with KMn04 and dicyclohexyl- 18-crown-6, Bu4NMn04, or NaMn04H20. ... 

An excellent means of protecting phenolic hydroxyl groups for reactions in alkaline media is by the formation of the methoxymethyl ether from the sodium salt of the phenol and chloromethyl ether, viz.,... 

The hydroxyl group of (+)-32 was protected as a methoxymethyl ether to give ether (+)-63 in 80% yield (Scheme 12). To reduce the carbonyl group of (+)-63 to a methylene moiety of (+)-66 (Scheme 13), we tried the thioacetal reduction method. However, the attempt was unsuccessful because of the exchange of the acetal group at the 1-position by a thioacetal group. Although we also tried the... 

Removal of the methoxymethyl groups from 43 with HCl, followed by protection of the secondary amine with benzyl chloroformate afforded the carbamate 9. Selective silylation of the 4-hydroxy group of 9 by treatment with 1.2 equiv of tert-butyldimethylsilyl chloride and 2.4 equiv of imidazole in DMF at room temperature for 1 h afforded the corresponding silyl ether as a single isomer in 80% yield that was subjected to acetylation at the C-3 hydroxyl group to afford the carbamate 11, which upon removal of the Cbz and TBDMS groups furnished 1. 

Protection of phenolic hydroxyl groups. Rail et al. encountered difficulties In methoxymethylation of the phenol (1) by standard procedures (reaction with lodium ethoxide, ethanol, and chloromethyl methyl ether). They then found... 

The protection of hydroxyl groups as methoxymethyl (MOM) ethers was achieved in a simple and convenient solvent-free reaction on alumina under sonication (Eq. 54).The reactions are generally reasonably fast and high-yielding and conditions are mild enough not to induce isomerization of double or triple bonds in allylic and propargylic alcohols. Alumina can be recycled after washing and reactivation. Without sonication, reactions were very slow. 

In the synthesis of methyl-2,3-0-isopropylidene-4-0-(methoxymethyl)-6-methylene-a-D-mannopyranoside (13), the hydroxyl groups of methyl-a-o-mannopyranosides are selectively protected 6-hydroxyl group as silyl ether 2,3-hydroxyl groups as acetonides and 4-hydroxyl group as methoxymethyle-ther. The silyl group at the C-6 position is then selectively cleaved to get primary alcohol. Oxidation of the alcohol to aldehyde followed by Wittig methylenation yields the desired olefin (13, Scheme 31.13). 

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