With potassium ethylxanthate

Treatment of pyridyl carbinol 51 with thionyl chloride leads to the corresponding chloride (52), Treatment of that intermediate with 5-methoxy-2-mercaptobenzimidazole (53), obtained from reaction of 4-methoxy-q-phenylenediamine with potassium ethylxanthate leads to displacement of halogen and formation of the sulfide (54). Finally, oxidation with 3-chloroperbenzoic acid produces the sulfoxide omeprazole (55) fl7]. 

Methoxyphenylene diamine 12 was treated with potassium ethylxanthate to afford benzimidazole-thiol 13. The coupling of thiol 13 and chloromethyl-pyridine 11 was then... 

Diazotized 2-aminothiazole (4) with potassium ethylxanthate yields ethylthiazolyl-2-xanthate (5), which is then hydrolyzed to 2-mercaptothiazole (3) (8). Similarly, treatment of (4) by potassium thiocyanate gives the 2-thiocyano derivative (6), which is hydrolyzed to 2-mercaptothiazole (3) by 50% sulfuric acid (Scheme 2) (9). 

Condensation of 1 in ethanol with potassium ethylxanthate gave210 the crystalline O-ethyl S-glycosyl xanthate 63 (R = Et) in high yield on treatment with cold methanolic ammonia, the compound underwent O- and S-deacetylation and 1 actonization, to give a hygroscopic product to which structure 64 has been ascribed. Treatment of 64 with diazomethane, followed by acetylation, resulted in the known201 1-thioglycoside derivative 61 (R = Me). 

The best method of synthesizing aminodithione 204 is from thiocarbohydrazide with potassium ethylxanthate [Eq. (53)]. Guha and De first carried... 

Alternatively, Horton and coworkers recommend the use of 2,3-disulfonic esters of methyl 4,6-O-benzylidene-a-D-glucopyranoside for the preparation of the olefin 45. Heating such compounds with potassium ethylxanthate in boiling butanol, or with the Tipson-Cohen reagent (N,N-dimethylformamide, sodium iodide, and zinc dust) afforded the product in 40-55% yield, and methyl 2,3-anhydro-4,6-0-benzylidene-a-D-allopyranoside and the 2,3-epithio analog also gave this compound under the former conditions.81 Applied to vicinal di-... 

A sixth route to the 2,3-alkene (73) has now been reported,involving the treatment of methyl 4,6-0-benzylidene-2,3-di-0-(methylsulfonyl)-a-D-glucopyranoside with potassium ethylxanthate in boiling 1-butanol. In addition,methyl 2,3-anhydro-4,6-0-benzylidene-a-D-allopyranoside gives rise to (73) on similar treatment. Yet another method of introducing a double bond into a carbohydrate ring involves the conversion of a 1,2-cis-diol into an alkene grouping by way of the derived thionocarbonate. By this means, benzyl 4-0-benzyl-2,3,6-trideoxy- 3-L-er2/[Pg.104]

Thio derivatives of D-glucuronic acid were synthesized by the condensation of methyl 2,3,4-tri-O-acetyl-a-D-glucopyranosyluronate bromide with potassium ethylxanthate. On saponification, the product (54) underwent 0- and (S-deacylation, de-esterification, and lactone formation, to give a product formulated as the thiolactone (55). Treatment of (55) with diazomethane, with subsequent acetylation, gave the known thio-glycoside derivative (56) of D-glucuronic acid. 

With potassium ethylxanthate in strong acid solution, technetium in the tetravalent or heptavalent state forms a purple complex which is readily extractable with carbon tetrachloride. Molybdenum behaves similarly (see page 320). 

Potassium ethylxanthate [140-89-6] M 160.3, m > 215°(dec). Crystd from absolute EtOH, ligroin-ethanol or acetone by addition of Et20. Washed with ether, then dried in a desiccator. 

Bromo-5-methyl-l,6-naphthyridin-2-amine (53) with potassium O-ethylxanthate gave 8-methylthiazolo [4,5-b] L,6]naphthyridin-2(3//)-thione (54) (reactants, l-methylpyrrolidin-2-one, 165°C, 7h >95%) the 3-phenyl analog was made similarly.928... 

Reactions.—Unsymmetrical dialkyl sulphides are obtained by the action of aqueous KOH, at 80 °C, on 05-dialkyl dithiocarbonates (with different alkyl groups) under phase-transfer conditions. The reaction depends on the liberation of a mercaptan and its alkylation by the 0-alkyl group of the diester. Ethoxythiocarbonyl derivatives of amino-acids are made by acylating the amino-acids with the stable reagent bis (ethoxythiocarbonyl) sulphide, (EtOCS)2S. This is prepared by an improved method from potassium ethylxanthate (2 mol) and ethyl chloroformate (1 mol). Esters of amino-acids are acylated by carboxymethyl... 

Procedure. 10 ml of the test solution are treated with about 50 ml of a saturated aqueous solution of potassium ethylxanthate and 50 ml of 2 AT hydrochloric acid. 40 ml of chloroform or carbon tetrachloride are added and the mixture centrifuged. The presence of technetium is indicated by a purple color in the organic layer. 

Intermediates in Reactions.— Attempts to prepare thiaziridines or selenaziridines by treatment of oxaziridines (133) with thiourea, potassium thiocyanate, potassium ethylxanthate, potassium selenoxanthate, and triphenylphosphine sulphide gave imines (135) instead, although... 

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