2-Methoxyethoxymethyl group

MECC micellar electrokinetic capillary chromatography MEM 2-methoxyethoxymethyl (group)... 

A 2-methoxyethoxymethyl ether was used to protect one phenol group during a total synthesis of gibberellic acid. 

The cleavage proceeds by initial reduction of the nitro groups, followed by acid-catalyzed cleavage. The DNB group can be cleaved in the presence of allyl, benzyl, tetrahydropyranyl, methoxyethoxymethyl, methoxymethyl, silyl, trityl, and ketal protective groups. 

From the intramolecular coupling product, just the two MEM-groups protecting the phenol functions (MEM = 2-methoxyethoxymethyl) have to be removed, in order to obtain the target molecule. 

The methoxymethyl (MOM) and (3-methoxyethoxymethyl (MEM) groups are used to protect alcohols and phenols as formaldehyde acetals. These groups are normally introduced by reaction of an alkali metal salt of the alcohol with methoxymethyl chloride or (3-methoxyethoxymethyl chloride.157... 

The dibromoalkene S-40 can be prepared from S-ethyl lactate by introduction of the MEM (methoxyethoxymethyl) protecting group, reduction to the O-protected lactaldehyde and Corey-Fuchs carbonyl olefination (Scheme 19). The l -enantiomer of 40 is available analogously from f -isobutyl lactate and serves as the reagent in the enantiomeric series. The lithium carbenoid S-41 is generated from S-40 by treatment with n-butyllithium in diethyl ether and reacted with aliphatic and aromatic aldehydes in tetrahydrofuran. High diastereoselectivities are reached, as shown in Scheme 19 . ... 

Benzylic ethers (Ph CH2 OR), allylic ethers (R-CH=CH-CH2 OR) and vinylic ethers [R CH=CH(OR)] together with the most commonly encountered tetrahydropyranyl ethers [THP-ethers, (5)] and /J-methoxyethoxymethyl ethers [MEM-ethers, R0CH2 0(CH2)2 0CH3] play an important role in the protection of a hydroxyl group (p. 550). Macrocyclic ethers (the crown ethers) are important phase transfer catalysts [e.g. 18-Crown-6 (6)]. 

Treating 3-acetoxy-2-methyl-4/f-pyrido[l,2-sodium hydrogen carbonate in methanol at 60°C for 4 hours, then at ambient temperature for 16 hours, gave 3-hydroxypyridopyrimidine-7-carboxylate 416 (84FES837). The free hydroxyl group of compound 416 was alkylated with an alkyl iodide in dimethylformamide in the presence of potassium carbonate at room temperature or with 2-methoxyethoxymethyl chloride in dichloromethane in the presence of diisopropylethylamine at ambient temperature for 3 hours to give 3-alkoxy derivatives 417. 

Abresoline (66) was prepared recently by Quick and Ramachandra by transesterification of MB-methoxyethoxymethyl (MEM) ether of methyl ferulate with MEM derivative of quinolizidol (63a) and cleavage of protective groups with trifluoroacetic acid (103). 

Methoxyethoxymethyl (MEM)-protected arylquinolizidines 25 and 27 were prepared from MEM-protected isovanillin (29) through the same sequence as shown in Scheme 2. Treatment of the alcohol 28, obtained by basic hydrolysis of 27, with the anhydride 30 gave 31 in 73% yield. Removal of the MEM groups with trifluoroacetic acid in methylene chloride afforded 10-epidemethoxyabreso-line (3) in 12% overall yield from 29. 

A 2-methoxyethoxymethyl ether (MEMOR) is normally prepared under non-acidic conditions in methylene chloride solution or under basic conditions. The MEM ether group can be removed in excellent yield with trifluoroacetic acid (TEA) in dichloromethane (1 1). The MEM group can also be removed by treatment with zinc bromide (ZnBr2), titanium chloride (TiCU) or bromocatechol borane. When MEM-protected diols are treated with zinc bromide (ZnBr2) in ethyl acetate, 1,3-dioxane is formed and a mechanism of this reaction is given in Scheme 1.23. 

HYDROXYL GROUPS t-Butylchlorodi-methylsilane. f-Butyldimethylsilyl perchlorate. f-Butyl chloromethyl ether. Chloromethyl methyl sulfide. 9-Chloro-9-phenylxanthene. 2-Chlorotetrahydro-furane. d-Methoxyethoxymethyl chloride. 2-Tetrahydrothicnyl diphenyl-acetate. Tris(p-bromophenyl)ammonium-yl hexachloroantimonate. 

Acyclic 0,0-acetals are used for the temporary protection of mono-alcohols. Most commonly used are the tetrahydropyranyl (THP), the methoxymethyl (MOM), the benzyloxymethyl (BOM), or the methoxyethoxymethyl (MEM) protecting groups. 

Alkoxymethyl Ethers The principal members of this set of protecting groups are methoxy-methyl ether (MOM) [188], methoxyethoxymethyl ether (MEM) [189], benzyloxymethyl ether (BOM) [190], /7-methoxybenzyloxymethyl ether (PMBM) [191], and trimethylsi-lylethoxymethyl ether (SEM) [192] (O Fig. 4). Since these protecting units are devoid of chirality, their use introduces no stereochemical complications. 

In an attempt to metalate a MEM-protected phenol with BuLi, the methoxy group was eliminated forming the vinyloxymethyl ether. This was attributed to intramolecular proton abstraction. A 2-methoxyethoxymethyl ether was used to protect one phenol group during a total synthesis of gibberellic acid. ... 

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