- Synthesis of Pyrimidine Derivatives by the Reaction of Ketene Dithioacetals with Amides
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Reactions of methyl 2-cyano-3,3-bis(methylthio)acrylate (1a) with carboxamides 2a-g in the presence of sodium hydride in a mixture of benzene and N,N-dimethylacetamide took place displacement with the methylthio group to give the corresponding methyl 3-N-acylamino-2-cyano-3-(methylthio)acrylates 3a-g which were readily converted to the corresponding pyrimidine derivatives at reflux in methanol in good yields.Reactions of 2-cyano-3,3-bis(methylthio)acrylonitrile (1b) with the carboxamides 2a-f gave directly pyrimidine-5-carbonitrile derivatives 7a-f.Ketene dithioacetals 1a,b smoothly reacted with thioamide 2g or urea 2h,i to give the expected pyrimidine derivatives 9,10a,b.Polyfunctionalized pyrimidines, thus obtained, were also used for the synthesis of fused pyrimidine derivatives.
- Kohra, Shinya,Tominaga, Yoshinori,Hosomi, Akira
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p. 959 - 968
(2007/10/02)
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- REACTION OF KETENETHIOACETALS WITH CARBOXAMIDES
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Reaction of methyl 2-cyano-3,3-bis(methylthio)-acrylate (1a) with carboxamides in the presence of sodium hydride in a mixture of benzene and N,N-dimethylacetamide gave the corresponding displacement products of methylthio group, methyl 3-(N-alkyl or aryl)carbamoyl-2-cyano-3-(methylthio)-acrylates (3a,b,c,d,e,f,g,h).Refluxing of 3 in methanol gave the corresponding cyclized product, 2-alkyl or 2-aryl-5-methoxycarbonyl-6-methylthio-4(3H)-pyrimidones (4).Compound 3a was allowed to react with amine(morpholine, benzylamine, cyclohexylamine, aniline) to give 4-(substituted amino)-4(3H)-pyrimidone derivatives (6a,b,c,d).
- Kohra, Shinya,Tominaga, Yoshinori,Matsuda, Yoshiro,Kobayashi, Goro
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p. 1745 - 1750
(2007/10/02)
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