Thioethyl

Metasystox A trade name for demeton-methyl, C[Pg.257]

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]. ... 

Chemical Designations - Synonyms Ethanethiol Ethyl Sulfhydrate Mercaptoethane Thioethyl alcohol Chemical Formula CjHjSH. 

The 2-methylthioethyl ester is prepared from a carboxylic acid and methyl-thioethyl 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). ... 

Pyridyl)ethyl, 677 2-(4 -Pyridyl)ethyl, 677 2-(3-Arylpyrimidin-2-yl)ethyl, 677 2-(Phenylthio)ethyl, 678 2-(4 -Nitrophenyl)thioethyl, 678 2-(4 -Triphenylmethylphenylthio)ethyl, 678 2-[2 -(Monomethoxytrityloxy)ethylthio]ethyl, 678 Dithioethanol Derivative, 679 2-(f-Butylsulfonyl)ethyl, 679 2-(Phenylsulfonyl)ethyl, 679 2-(Benzylsulfonyl)ethyl, 679... 

A solution of 69g of sodium in 1,380 ccof absolute alcohol is mixed with 257.4 g of /3-methyl-thioethyl-d -methyl)-n-butvl-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 j3-methvl-thioethyl-(1 -methyD-n-butyl-cyano-ecetyl thiourea forms yellowish green crystals having a melting point of 229°C to 230°C. 

Although the 3 - and 5 -polyphosphate derivatives mentioned above exhibit exquisite inhibitory potency these compounds are not cell permeable. To take advantage ofthepotency of such derivatives for studies with intact cells and tissues, there are two possibilities. One is chemically to protect the phosphate groups from exonucleotidases that also allows the compound to transit the membrane intact. The other is to provide a precursor molecule that is cell permeable and is then metabolized into an inhibitor by intracellular enzymes. The general term for such a compound is prodrug nucleotide precursors are also referred to as pronucleotides. Families of protected monophosphate derivatives were synthesized, based on (3-L- and 3-D-2, 5 -dd-3 -AMP, 3-L-2, 3 -dd-5 -AMP, and the acyclic 9-substituted adenines, PMEA and PMPA. Protective substituents were (i) -( -pivaloyl-2-thioethyl) ... 

SOLID SUPPORT GLYCAL ASSEMBLY VIA THIOETHYL GLYCOSYL DONORS 25... 

Polymer-supported glucal 37 was converted to the protected thioethyl glucosyl donor 39 as outlined in Scheme 2.11. Compound 37 was first epoxidized by the action of DMDO. The resulting 1,2-anhydrosugar was opened by a mixture of ethanethiol and dichloromethane (1 1) in the presence of a trace of trifluoroacetic acid. Polymer-bound 38 was thus obtained in 91% yield. This was a substantial improvement over the 78% yield obtained by the same protocol in solution. Protection by reaction with pivaloyl chloride occurred in quantitative yield to furnish 39a. 

Scheme 2.11 Synthesis of polymer-bound thioethyl glucosyl donor.

Scheme 2.13 Synthesis of a branched trisaccharide via thioethyl donors.

SOLID SUPPORT ASSEMBLY VIA THIOETHYL 2-AMIDOGLYCOSYL DONORS 27... 

Scheme 2.16 Synthesis of disaccharides using a polymer-bound thioethyl 2-aminoglucosyl donor.

The polymer bound thioethyl 2-amido glucosyl 51a is a competent 2-amidoglucosyl donor toward glycal acceptors when activated with methyl triflate in the standard manner.21 The formation of P-2-aminoglucosyl C1 —>4 53) and p-2-aminoglucosyl (1—>3 54)-linked disaccharides proceeded in over 70% yield (Scheme 2.16). The P-2-aminoglucosyl (1 —>6)-linked disaccharide 52 was formed in lower yields. 

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