Methylthiomethyl esters

Methylthiomethyl Ester (MTM Ester) RCOOCH2SCH3 (Chart 6) Formation... 

Carboxylic acids react under Pfitzner-Moffatt conditions, resulting in the formation of methylthiomethyl esters and /V-acylureas.41 Nevertheless, although the authors are not aware of any report involving the selective oxidation of alcohols in the presence of a carboxylic acid, such outcome would be likely with carboxylic acids with little nucleophilicity, as standard Pfitzner-Moffatt oxidations are performed in the presence of trifluoroacetate that is known for not to interfere. 

Methylthiomethylesters.1 Treatment of DMSO with n-butyllithium followed by tri-n-butylborane affords the ate complex CH3S(0)CH2BBu3Li+(l), which converts acid chlorides into methylthiomethyl esters. 

Methylthiomethyl esters have been prepared by reaction of trie thy lammonium salts of carboxylic acids with chlorodimethylsulfonium chloride191 or by reaction of the potassium salts of carboxylic acids with chloromethyl methyl sulfide in the presence of sodium iodide and 18-crown-6.192... 

In 1968 Miller and Stirling showed that the 2-tosylethyl ester function (abbreviated TSE) underwent easy base-catalysed elimination in the presence of 1 M sodium hydroxide or sodium carbonate (but not sodium hydrogen carbonate) in aqueous dioxane at room temperature to give p-toluenesulfinate anion, ethylene. and a carboxylate 215 Thus, this ester function complements the methylsul-fonylmethyl function (see section 6.4) derived from methylthiomethyl esters in its base-sensitivity. Electron withdrawing groups (e.g., p-nitro) on the aryl ring increase base lability — a feature that has been exploited for the protection of the 2f hydroxyl function in oligoribonucleotide synthesis.216... 

Methylthiomethyl esters. Carboxylic acids are converted into their methylthiomethyl esters by reaction with t-butyl bromide-dimethyl sulfoxide in the presence of sodium bicarbonate. Methylthiomethyl esters of N-protected amino acids can be obtained in high yield without racemization by this method. ... 

Methyl-2(l//)-pyridothione, 40, 41 N-Methyl-2-pyrrolidone, 127, 316 20-Methylsirohydrochlorin, 345 a-Methylstilbene, 488 (3-Mcthylstyrene, 66 a-Methylthiocarbonyl ketones, 181 Methylthiomethyl esters, 105, 107, 190 Methylthiomethyl ethers, 107, 190 N,N-Methyltosylhydrazones, 411... 

Methylthiomethyl esters (4, 84-85). These esters can also be prepared by reaction of the triethylammonium salts of carboxylic acids with the Corey-Kim reagent and excess triethylamine initially at —70° and then at 20° for 30 minutes. Yield 80-85%. 

Protection of carboxyl groups (8, 94). Two new methods for deprotection of methylthiomethyl esters have been reported one involves oxidation to the sulfone followed by alkaline hydrolysis, and the other involves methylation to a sulfonium iodide and hydrolysis. ... 

Melhybkiomethylesters. Methylthiomethyl esters are useful as protective groups for carboxylic acids. They are prepared by treatment of the acid with the reagent and... 

Methyl-A > ( 1 >testosterone, 239, 2-Methyl-3-thiazoline, 344 Methylthiomethyl esters, 84-85 Methyl 3-thiophenecarboxylate, 70 l-Methyl-3-p-tolylhydrazine, 345 Methyl p-tolyl sulfoxide, 466, 513... 

METHYLTHIOMETHYL ESTERS Chlo-romethyl methyl sulfide. MONOBROMOCYCLOPROPANES Sodium bistrimethylsilylamide. NAPHTHALENE 1,2-oxide ... 

Hydrolysis of methylthiomethyl esters. The method has been applied to the synthesis of phosphoserine and phosphothreonine. 

Methylthiomaleic anhydride, 351-352 Methylthiomethyl esters, 94 Methylthiomethyl ethers, 464... 

Protection of carboxyl groups as methylthiomethyl esters Removal of the protective group... 

Protection of carboxyl groups using methylthiomethyl esters can be reversed either by oxidation with HjOj or methylation, followed by mild hydrolysis. ... 

Two very efficient methods for the cleavage of methylthiomethyl esters have been developed, both of which avoid the highly acidic conditions encountered when mercuric salts are used. One involves an ammonium molybdate-catalysed peroxide oxidation to the sulphone followed by aqueous base hydrolysis whereas the second, perhaps simpler, procedure consists of methylation (Mel) and brief treatment of the resulting salt with aqueous base. 

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