کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5218995 | 1383344 | 2012 | 8 صفحه PDF | دانلود رایگان |
In this paper we report synthesis of a series of aromatic fused pyrimidine-2,4(3H)-dione-1-yl acetic acid and new PNA monomers containing these polycyclic nucleobase analogues. Introduction of a fused aromatic ring onto the 5,6-positions of the pyrimidine-2,4-[1H,3H]-diones brings about the steric effects and the charge delocalization, both weakening the nucleophilic substitutions on the 1- and 3-positions. We found that alkali metal cations play an important role in this alkylation reaction. LiOH brings out a much more efficient alkylation than NaOH does, while KOH nearly does not work on this reaction. Such influences from the alkali metal cations are probably due to that the charge-pairing interactions between the pyrimidine-2,4-dioxide anions and the alkali metal cations rearrange the charge distribution around the whole aromatic system and increase the negative charge distribution on the 1- and 3-nitrogen atoms, which then strengthens the nucleophilic reactivity on these positions.
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Journal: Tetrahedron - Volume 68, Issue 43, 28 October 2012, Pages 8908–8915