Ethyl-a-mercaptoacetate

On the other hand, 4-amino-5-carbethoxy-2-methylthiothiazole (260) was obtained by condensing methyl-N-cyanoiminodithiocarbamic esaer (259) with ethyl-a-mercaptoacetate (258) in foramidine in the presence of triethylamine (Scheme 133) (564). 

A direct and versatile synthesis of the thieno[2,3-6 ]pyrazine ring system was found by Schneller and coworkers and consists of the reaction of 2-chloro-3-cyanopyrazine (361) with ethyl a-mercaptoacetate in the presence of sodium carbonate (Scheme 106) (75JHC513, 76JHC273 cf. 79MI31703). The conversion of (362) to thieno[2,3- >]pyrazine (363) is accomplished by straightforward methods. The compound (363) forms colorless crystals with m.p. 44 °C. 

Keywords aldimine, ethyl-a-mercaptoacetate, ethyl-a-cyanoacetate, basic alumina, microwave irradiation, /Mactams... 

Miscellaneous Fused Systems.— Ethyl 3-aminothieno[2,3- ]pyrazine-2-carboxyIate has been prepared from 2-chloro-3-cyanopyrazine and ethyl a-mercaptoacetate, and then converted into (269) by reaction with formamide. Other derivatives of (269) were subsequently prepared. Fused thieno[3,2-c/]-y/c-triazin-4-ones... 

In another example of a tandem displacement/annulation sequence, Neidlein and co-workers reported the reaction of ethyl 2-mercaptoacetate with chlorocyanopyrimidine 47 <00S255>. Thienopyrimidine 48 was produced in high yield through this one-pot procedure. 

The addition of a mercaptide to a nitrile provides the key reaction to the preparation of a thiazolidinone that shows diuretic activity. The hrst step in the reaction of ethyl 2-mercaptoacetate (105-2) with ethyl cyanoacetate (105-1) thus probably leads hrst to the formation of the addition product (105-3). The imino... 

With the success of this three-component tandem polymerization, we further explored such polymerization by changing the third component monomer from ethyl 2-mercaptoacetate 14 to a normal thiol 16. We aimed to extend the scope of the one-pot, two-step, three-component coupling-addition tandem polymerization... 

A few isothiazoles, 2,1-benzisothiazoles and monocyclic sultams have been prepared by methods involving formation of the 4,5-bond. Thus, condensation of a-cyanooximes (179) with ethyl mercaptoacetate or related compounds gives a compound (180) which cyclizes... 

A distantly related acid with a more highly functionalized ring shows choleretic rather than antiinflammatory activity. That is, the compound is useful in those conditions in which the flow of bile is to be increased. Construction of the thiazolone ring is accomplished by a method analogous to that used above to build the thiazole ring. Thus, condensation of ethyl mercaptoacetate with ethyl cyanoacetate leads to the thiazolinone (203) an intermediate such as 202, involving addition of mercaptide to the nitrile function, can be reasonably invoked. 

The thiomethyl group has also been employed as a leaving group. Treatment of 364a-f with the anion of ethyl mercaptoacetate followed by sodium ethoxide generates 365a-f (Equation 134) <2003J1C311>. 

One example of the synthesis of a thienopyrimidine commencing with a pyrimidine precursor appeared in 2006. Thus, 4-chloro-5-cyano-6-aryl-2-methylthiopyrimidines react with either ethyl (or f-butyl) 2-mercaptoacetate to afford 5-amino-4-aryl-2-methylthiothieno[2,3-,y]pyrimidine-6-carboxylic acids <2006JMC3888>. 

Bourguignon and coworkers in their preparation of thieno[2,3-6]pyrazine used methyl-pyrazine (364 Scheme 107) (80JHC257) as starting material. The chlorination of (364) yields 2-chloro-3-methyl- and 2-chloro-6-methyl-pyrazine in a ratio of 80 20. Without separation this mixture is treated with ethyl mercaptoacetate in the presence of sodium ethoxide to give (365) in 91% yield (based on 2-chloro-3-methylpyrazine). Oxidation of the methyl group to an aldehyde function and subsequent base catalyzed ring closure yields (366), which is transformed to (363) by the method depicted already in Scheme 106. 

Cyclocondensation of ethyl 2-methylthio-4-oxo-4/f-pyrido[l,2-a]py-rimidine-3-carboxylate 459 and ethyl mercaptoacetate in acetonitrile in the presence of potassium carbonate at 60°C for 2 hours, then at room temperature for 16 hours gave pyrido[l,2-a]thieno[2,3-t/]pyrimidine-2-carboxylate 460 (88CP1232904). 

Cyclocondensation of 3 - c y a n o - 2 - m e t h y 11 h i o - 4 //- p y r i d o [ 1,2-a]pyrimidin-4-ones and ethyl mercaptoacetate in boiling EtOH in the presence of NaOEt afforded 4//-pyrido[l,2-a]thieno[2,3-(/]pyrimidin-4-ones 210 (00HC571). 2-Methylthio-4-oxo-4i7-pyrido[l,2-a]pyrimidine-3-carboxylates 211 and mercaptoacetates afforded tricyclic derivatives 212 (93MIP1). Cyclocondensation of 2-methylthio-4-oxo-4i/-pyrido[l,2-a]pyrimidin-3-car-bonitriles 213 with E NNE -E O and with guanidine El Cl afforded tricyclic derivatives 214 and 215, respectively (96FES781). 

Dihydrogen TctrakisicarboxymethylthioIatoltellurateCII)1 Sodium tellurite and mercaptoacetic acid are combined in a 1 8 molar ratio in 1 normal sulfuric acid. The resultant mixture is extracted with ethyl acetate, the organic phase is shaken repeatedly with aqueous cadmium chloride solution to remove excess mercaptoacetic acid, the organic phase is dried with sodium sulfate, the mixture is filtered, and the solvent is evaporated at 0° under reduced pressure to leave yellow crystals of the product. 

Enantioselective alkylation of HSCHjCOOH S-MBF-mercaptoacetic acid (3), colorless oil, an -1-270°, obtained by reaction of the acid with 2 in the presence of a trace of HCl, is stereoselcctively methylated or ethylated in favor of the (R)-diastereomcr (54% ee and 60% ce, respectively). The (S)-diastereomer is removed by esterification of the mixture and subsequent chromatography. 

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