- Synthesis of some pyrimidine N-oxides
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Various monosubstitudes pyrimidines and methylpyrimidines were N-oxidized with a number of different peracids.In general, they are more susceptible to side reactions accompanying N-oxidation (i.e., decomposition, annular carbon oxidation, ring opening) than other ?-deficient diazine and triazine analogs.Unsymmetrical pyrimidines, which can potentially yield two isomeric products, were N-oxidized preferentially at the site para to strong electron-donating substituents.Weaker ringactivating groups, such as methyl, are mainly ortho directing and only aid in the N-oxidation of pyrimidine nuclei having ortho/para-directing substituents.
- Jovanovic, Misa V.
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p. 1176 - 1180
(2007/10/02)
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- OXIDATION OF 2,4-DISUBSTITUTED PYRIMIDINES WITH ORGANIC PERACIDS
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While 4,6-disubstituted (alkyl, aryl, alkoxyl) pyrimidines easily afforded the corresponding mono-N-oxides with hydrogen peroxide in glacial acetic acid, pyrimidine derivatives whose 6-position is free, are partly oxidatively degradated during N-oxidation reaction.The oxidation of the latter compounds under the above conditions gave 2,4-disubstituted imidazoles together with their mono-N-oxides.A likely mechanism of this ring-contraction and the improved conditions for the synthesis of the N-oxides are also described.
- Yamanaka, Hiroshi,Ogawa, Shigeru,Sakamoto, Takao
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p. 573 - 576
(2007/10/02)
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