4- Methylthio-7- thieno pyrimidine

Bromination of 5-allyl-6-methyl-2-methylthio(phenyl)pyrimidine-4-thiols (144) in chloroform afforded 6-bromomethyl-4-methyl-2-melhylthio(phenyl)-5,6-di-hydrothieno[2,3-<7]pyrimidines 145. The latter were transformed into 4,6-dimethyl-2-methylthio(phenyl)thieno[2,3-<7]pyrimidines 146 by refluxing with ethanolic sodium ethoxide (1999KZA60). 

Cyclocondensation of 3-cyano-2-methylthio-4//-pyrido[l, 2-u]pyrimidin-4-ones and ethyl mercaptoacetate in boiling EtOH in the presence of NaOEt afforded 4//-pyrido[l,2-u]thieno[2,3-r/ pyrimidin-4-ones 210 (00HC571). 2-Methylthio-4-oxo-4//-pyrido[l,2-u]pyrimidine-3-carboxylates 211 and mercaptoacetates afforded tricyclic derivatives 212 (93MIP1). Cyclocondensation of 2-methylthio-4-oxo-4//-pyrido[l, 2-u]pyrimidin-3-car-bonitriles 213 with H2NNH2 H2O and with guanidine HCl afforded tricyclic derivatives 214 and 215, respectively (96FES781). 

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). 

Thienopyrimidyl-2-thioacetamido)cephalosporanic acid derivatives 170 were prepared by reaction of the appropriate 7/3-chloroacetamidoceph-alosporanic acids 169 with the thieno[2,3-d]pyrimidine potassium salts 168 (87PHA160). The 4-methylthio group of quaternized thieno[2,3-d]pyrimi-dine 172 was displaced by the 3-aminomethyl group of cephalosporins 171 to afford cephalosporin derivatives 173 (89AUP584898). 

Thieno[3,2-d]pyrimidine-2(l//)-thiones 217-219 and -4(3//-thiones 245 were S-methylated smoothly with methyl iodide in base to the corresponding 2-methylthio (82EUP43054 89CPB1197) and 4-methylthio (86JHC 1757) compounds. 5-Alkylation of thieno[3,2-d]pyrimidin-4(3//)-one-2(l//)-thione 223 with alkyl halides in dilute sodium hydroxide solution afforded 2-alkylthio derivatives 284. Nucleophilic displacement of the alkyl-thio group in compound 284 by primary amines has also been reported (90EUP404356). 

The reaction of the salt 308 with alkyl halides in base gave the corresponding 2-alkylthiothieno[3,4-d]pyrimidin-4(3//)-ones 369. Heating the latter with ammonia or amines afforded 2-amino(or substituted amino)thieno[3,4-d]pyrimidin-4(3//)-ones 370 (90EUP404356). When 2-methylthiothieno[3,4-d]pyrimidin-4(3//)-one 360 was heated with o-tolu-idine at 200°C, displacement of the 2-methylthio group afforded compound 372 (91MIP1). 

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