2-Chloro-4H-pyrido[1,2-a]pyrimidin-4-one (1) was utilized as a synthone precursor to prepare novel heterotricyclic systems. 2-Azido and 2-hydrazino derivatives (2 and 3) were obtained by nucleophilic replacement evolving compound 1. The hydrazine derivative 3 was transformed into the azido derivative 2 by nitrosation. Treatment of compound 3 with [bis(methylthio)methylene] malononitrile afforded 2-pyrazolylpyridopyrimidine 4. When compound 1 was reacted with 5-amino-3-(methylthio)-1H-pyrazole-4-carbonitrile, the same compound 4 was obtained with no evidence for the production of (pyrazolylamino) pyridopyrimidine 5 or pyrazolodipyridopyrimidine 6. Poly-functionalized dipyridopyrimidine 8 was obtained by reaction of compound 1 with 2-[(methylthio)-( phenylamino)methylene]propanedinitrile. Cyanoguanidine was reacted with compound 1 to afford N-pyridopyrimidinylguanidine 9, which was subjected to cyclization reaction, in presence of piperidinium acetate, to give pyridopyrimidopyrimidine 10.
利用 2-氯-4H-吡啶并[1,2-a]嘧啶-4-酮(1)作为合成前体来制备新型杂环系统。通过亲核置换演化出化合物 1,得到了 2-叠氮和 2-肼衍生物(2 和 3)。 肼衍生物 3 通过亚硝基化转变成叠氮衍生物 2。将化合物 3 与[双(甲硫基)亚甲基]丙二腈处理,可得到 2-吡唑基吡啶嘧啶 4。当化合物 1 与 5-氨基-3-(甲硫基)-1H-吡唑-4-甲腈反应时,得到了相同的化合物 4,但没有证据表明生成了(吡唑氨基)吡啶嘧啶 5 或吡唑二吡啶嘧啶 6。化合物 1 与 2-[(甲硫基)-(苯基氨基)亚甲基]丙二腈反应,得到了多官能团二吡啶嘧啶 8。氰基胍与化合物 1 反应得到 N-吡啶基嘧啶胍 9,在哌啶乙酸盐存在下进行环化反应,得到吡啶基嘧啶嘧啶 10。