Thieno pyrimidine-4 -thione alkylation

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). 

Cycloaddition and cyclization routes were used to access certain 1,3-diazines. The 4+2 cycloaddition reaction of 4-(N-allyl-N-aryl)amino-l,3-diaza-l,3-butadienes with vinyl-, isopropenyl-, and chloroketene led to pyrimidinone-fused pyrimidinones <97T13841>. Cis-cyclopenta[d]pyrimidines were derived from cis-2-amino-l-cyclopentanecarboxylates by cyclization with KOCN and KSCN <97JHC1211>. 2-Thioxopyrido[3, 2 4,5]thieno[3,2-r/]pyrimidin-4(3//)-ones 19 were prepared by cyclocondensation of 2-carbethoxy-3-amino-4-phenyl-6-substituted-thieno[2,3-/)]pyridines and isothiocyanates <97JHC937>. Thiazolyl-benzimidazoles derived from 2-cyanomethyl-l//-benzimidazole and 2,3-dihydrothiazole-2-(3//)-thiones were cyclized to the corresponding thiazolo[4,5-r/]pyrimidines <97PHA346>. Reductive cyclization of 6-cyanomethyl-5-nitropyrimidines afforded 7-alkyl-5//-pyrrolo[3,2-r/]pyrimidines and 6-amino-7,7-dialkyl-7//-pyrrolo[3,2-rf]pyrimidines <97T391>. 7-Methyl-5-alkyl-2-vinyl-pyrazolo[3,4-r/]pyrimidine-4,6(5//,7//)-diones arose from cyclization and alkylation of... 

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