A Simple and Convenient Procedure for Lithiation and Side-Chain Substitution of 2-Alkyl-4-(methylthio)quinazolines and 2-Alkyl-4-methoxyquinazolines
作者:Keith Smith、Gamal A. El-Hiti、Amany S. Hegazy
DOI:10.1055/s-2005-916036
日期:——
2-Methyl-4-(methylthio)quinazoline has been lithiated, in the 2-methyl group, with n-BuLi at -78 °C in THF. The lithium reagent thus obtained reacts with a variety of electrophiles (iodomethane, iodoethane, D2O, benzaldehyde, 4-anisaldehyde, hexan-2-one, acetophenone, benzophenone, cyclohexanone) to give modified 2-substituted 4-(methylthio)quinazolines in excellent yields. Similarly, lithiation of 4-methoxy-2-methylquinazoline followed by reactions with various electrophiles gave the corresponding modified 2-substituted 4-methoxyquinazolines in excellent yields. Lithiations of 2-ethyl-4-(methylthio)quinazoline, 4-(methylthio)-2-propylquinazoline, 2-ethyl-4-methoxyquinazoline and 4-methoxy-2-propylquinazoline, followed by reactions with a range of electrophiles, behave in a similar manner to give the corresponding modified 2-substituted derivatives in good yields.
2 甲基-4-(甲硫基)喹唑啉与正叔丁基锂在 -78 °C 的四氢呋喃中发生 2-甲基的锂化反应。由此得到的锂试剂可与多种亲电体(碘甲烷、碘乙烷、D2O、苯甲醛、4-甲氧基苯甲醛、2-己酮、苯乙酮、二苯甲酮、环己酮)反应,以优异的产率得到改性的 2-取代基 4-甲硫基喹唑啉。同样,4-甲氧基-2-甲基喹唑啉经锂化后与各种亲电体反应,也能以极高的收率得到相应的改性 2-取代的 4-甲氧基喹唑啉类化合物。2- 乙基-4-(甲硫基)喹唑啉、4-(甲硫基)-2-丙基喹唑啉、2-乙基-4-甲氧基喹唑啉和 4-甲氧基-2-丙基喹唑啉的石灰化反应,然后与一系列亲电体反应,也以类似的方式得到相应的改性 2-取代衍生物,产率极佳。