Michael versus retro-Michael reaction in the regioselective synthesis of N-1 and N-3 uracil adducts
作者:Sławomir Boncel、Maciej Mączka、Krzysztof Z. Walczak
DOI:10.1016/j.tet.2010.08.059
日期:2010.10
controlling the temperature or reaction time in the base-catalysed Michael-type addition of 5-substituted uracil derivatives we were able to synthesise N-1 or N-3 uracil adducts using methyl acrylate and acrylonitrile as acceptors. The mechanism of this chemical inequivalence was established using 1H NMR spectroscopic studies. The investigations revealed that formation of the N-1 adduct was achievable
通过控制5-取代的尿嘧啶衍生物在碱催化的迈克尔型加成反应中的温度或反应时间,我们能够使用丙烯酸甲酯和丙烯腈作为受体合成N-1或N-3尿嘧啶加合物。使用1 H NMR光谱研究确定了这种化学不等价的机理。研究表明,无论所用碱类(TEA,DBU)如何,在动力学控制条件下均可形成N-1加合物。反过来,N-3加合物的合成是从最初形成的N-1,N-3二加合物通过逆迈克尔反应进行的,该反应在升高的温度或延长的反应时间中起主导作用。
New approach for the synthesis of 1-aryl- and 1-heteroaryl-5-nitrouracil derivatives
作者:Andrzej Gondela、Krzysztof Walczak
DOI:10.1016/j.tet.2007.01.040
日期:2007.3
1-(2,4-Dinitrophenyl)-5-nitrouracil and its 3-methyl derivatives were synthesized and used as substrates in reaction with aromatic amines and amino pyridines. In the reaction of aniline with 1-(2,4-dinitrophenyl)-5-nitrouracil, only the acyclic adduct was isolated. When 1-(2,4-dinitrophenyl)-3-methyl-5-nitrouracil was treated with aniline and other aromatic amines or amino pyridines, the desired 1-aryl-5-nitrouracil