2-Methylthioethyl esters

The 2-methylthioethyl ester is prepared from a carboxylic acid and methylthioethyl alcohol or methylthioethyl chloride (MeSCH2CH20H, TsOH, benzene, reflux, 55 h, 55% yield MeSCH2CH2Cl, Et3N, 65°, 12 h, 50-70% yield). It is cleaved by oxidation [H2O2, (NH4)6Mo7024, acetone, 25°, 2 h, 80-95% yield pH 10-11, 25°, 12-24 h, 85-95% yield] and by alkylation followed by hydrolysis (Mel, 70-95% yield pH 10, 5-10 min, 70-95% yield). ... 

This ester is similar to the 2-methylthioethyl ester in that it is prepared from a thioethyl alcohol and cleaved by oxidation [H2O2, (NH4)6Mo7024]. ... 

The 2-methylthioethyl ester is prepared from a carboxylic acid and methylthioethyl alcohol or methylthioethyl chloride (MeSCH2CH20H, TsOH, benzene, reflux, 55 h. 

A solution of 69 g of sodium in 1,380 cc of absolute alcohol is mixed with 257.4 g of p-methylthioethyl-(l-methyl)-n-butyl-cyano-acetic acid ethyl ester and 114 g of thiourea and the whole mass boiled under reflux with stirring for six hours. After concentration under vacuum the residue is taken up in 1.5 liters of water and shaken up thrice, each time with 300 cc of ether. The aqueous alcoholic layer is stripped, under vacuum, of the dissolved ether and mixed with 300 cc of 30% acetic acid under stirring and ice cooling. The precipitated material is sucked off, washed with water, dried and recrystallized from isopropyl alcohol. The thus obtained p-methyl-thioethyl-(l-methyl)-n-butyl-cyano-acetyl thiourea forms yellowish green crystals having a melting point of 229°C to 230C. 

Further work with diphenylmethyl, phenacyl, and p-methylthioethyl 5 esters disclosed useful combinations with K-protecting groups, particiilarly trityl and o-nitrophenylsulfenyl groups. 

Addition to C=C. Chiral a-arylpropanoic esters are generated by the union of arylketenes with alcohols in the presence of 62. An arylselenomethoxylating agent that depends on an o-(a-methylthioethyl group to exert its enantioselectivity is prepared in situ from the diaryl diselenide by treatment with bromine and AgOTf. Another chiral reagent is e dr>-3-bomylselenyl triflate. ... 

Methyl, ethyl, benzyl, benzhydryl, p-nitrobenzyl, p-methoxy-benzyl, 4-picolyl, j3j -trichloroethyl, j3-methylthioethyl, /J-p-toluenesulphonylethyl, and -p-nitrophenylthioethyl esters may be prepared directly from the acid and alcohol. TTie most usual method [4, 5] consists of heating the acid and an excess of the alcohol with an acid catalyst (e.g., Fischer-Speier, hydrochloric or sulphuric acid). The extent of reaction is improved if the water formed is removed by azeotropic distillation with an inert solvent (benzene, carbon tetrachloride, or chloroform). Considerable variation is possible in the natvire of the acid catalyst thus phosphoric acid [6], aryl sulphonic acids [7, 8, 9], alkyl sulphates [10], and acidic ion-exchange resins [11] may be employed. Removal of the water by azeotropic distillation during the formation of methyl esters is difficult and Brown and Lovette [12] introduced the novel reagent acetone dimethyl acetal (7) for the direct formation of methyl esters. In the presence of a trace of methanol and an acid catalyst the reagent acts as a scavenger of water formed by esterification and liberates further methanol for reaction. 

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