Thieno pyrimidin-4 -one alkylation

Unsubstituted thieno[2,3-d]pyrimidin-4(3//)-one 2a was converted into the trimethylsilyl derivative 137 by heating in hexamethyldisilazane. Silyl derivative 137 was alkylated at N-3 with l-0-acetyl-2,3,5-tri-O-benzoyl-/3-D-ribofuranose in the presence of stannic chloride in 1,2-dichloroethane or... 

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). 

Annulation reactions of 5 (X=PPhj) with isocyanates, carbon disulfide or carbon dioxide give rise to pyridino[3 2 4,5]-thieno[3,2-d]pyrimidine derivatives. Interesting selectivity is noted in the reactions of 10 with RNCX(X=0,S) in that when R=alkyl cyclization involving both phosphoranimines occurs whereas when R=aryl cyclilzation involves the phosphoranimine directly attached to the arene and the =CHAr center leaving one phosphoranimine intact. Hydrolysis of the remaining center results in formation of the primary amine. 

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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