3-Hydroxy-4-methylthiazol-2 -thione

Hy(iroxy-4-niethylthiazole-2(3//)thione carbamates, e.g. the cyclohexyl derivative 336, are precursors for monoalkylaminium cation radicals, which cannot be prepared from 2-thioxopyridinyloxycarbamates. The carbamate is obtained from 3-hydroxy -methylthiazole-2(3ff)-thione and cyclohexyl isocyanate. When irradiated in the presence of malonic acid and t-butyl hydrogen sulphide it yields the cyclohexylaminium cation... 

Figure 5-3. Biocides bromo-2-nitropropane, 1-N-hexadecyl-1,2,4-tri-azole bromide, 3-hydroxy-4-methylthiazol-2(3H)-thione, 3-hydroxy-4-phenylthiazol-2(3H)-thione, 2,3-dibromo-1-chloro-4-thiocyanato-2-butene, 1,2-dibromo-2,4-dicyanobutane, 2,2-dibromo-2-nitroethanol.

Thiazole A -oxides can easily be alkylated on the oxygen. For example, Ar-(alkoxy)-5-(p-methoxyphenyl)-4-methylthiazole-2(377)-thiones were prepared from Ar-(hydroxy)-5-( -methoxyphenyl)-4-methylthiazole-2(3//)-thione tetraethylammonium salt and an appropriate alkyl chloride or tosylate in moderate to good yields <20060BC2313>. A -Methoxythiazole-2(377)-thiones were synthesized from the A -hydroxythiazole-2(3//)-thiones by treatment first with a tetraalkylammonium hydroxide in methanol and then methyl ra-toluenesulfonate in DMF <2005EJ0869>. 

An alternative procedure for reductive decarboxylation without the use of trialkyltin hydrides as hydrogen atom donors has been developed Alkane carboxylic acid esters derived from AT-hydroxypyridine-2-thione decomposed to alkyl radical, which can readily accept a hydrogen atom from t-BuSH (equation 74) to give alkanes. This reaction can be conveniently performed as a one-pot experiment wherein the acid chloride of an alkane carboxylic acid, the sodium salt of thiohydroxamic acid, t-BuSH and 4-dimethyl-aminopyridine (DMAP) in benzene solution are heated to reflux. This procedure works well for COOH groups attached to primary and secondary carbon atoms. Instead of AT-hydroxypyridine-2-thione, one can use other thiohydroxamic acids, viz. iV-hydroxy-AT-methylthiobenzamide, 3-hydroxy-4-methylthiazole-2(3if)-thione (equation 75) and l-iV-hydroxy-3-AT-methylbenzoylenethiourea for decarboxylation reactions. 

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