Effect of substituent structure on pyrimidine electrophilic substitution: a rebuttal
作者:Virginija Jakubkienė、Inga Čikotienė
DOI:10.1016/j.tet.2012.01.044
日期:2012.3
obscure effects influencing the electrophilic nitrosation of activated pyrimidines (Tetrahedron 2007, 63, 5394) was shown to be erroneous. Instead of electrophilic substitution at position 5 of the pyrimidine ring, N-nitrosation of the secondary amino group in the 4-position of the pyrimidine ring took place. Moreover it was shown that the synthetic sequence for the preparation of purines is also incorrect
nucleophilic substitution reaction with amines. The subsequent treatment of the obtained products with aq H2SO4 can lead to either N-denitrosation to obtain 4,6-pyrimidinediamines or to a Fischer-Hepp type rearrangement to obtain 5-nitroso-4,6-pyrimidinediamines. It was found that the outcome of the reaction strongly depends on the structure of the pyrimidines. Activation of the pyrimidine ring by three
N-亚硝基部分可用于将氯嘧啶活化为与胺发生亲核取代反应。所得产物用 aq H2SO4 进行后续处理可导致 N-脱亚硝基得到 4,6-嘧啶二胺,或导致 Fischer-Hepp 型重排以得到 5-亚硝基-4,6-嘧啶二胺。发现反应的结果在很大程度上取决于嘧啶的结构。三个具有正中间体效应的基团激活嘧啶环对于分子内亚硝基迁移至关重要。