A New Versatile Synthesis of Xanthines with Variable Substituents in the 1-, 3-, 7- and 8-Positions
作者:Christa E. Müller、Jesús Sandoval-Ramírez
DOI:10.1055/s-1995-4082
日期:1995.10
A new convenient procedure for the synthesis of a wide range of xanthines has been developed starting from 3-substituted 6-aminouracils. Nitrosation and reduction yields the corresponding 5,6-diaminouracils, which are condensed with carboxylic acids. The resulting amides can be selectively alkylated at the uracil ring nitrogen N-1 (corresponding to xanthine N-3) under mild conditions. Ring closure and, if desired, alkylation at the 7-position, yields di-, tri-, or tetrasubstituted xanthines in high yields. Sensitive substituents, such as prop-2-ynyl, can be introduced in the 1-position. Variation of the 3-substituent is considerably facilitated in comparison with the standard procedure for the preparation of xanthines.
从 3-取代的 6-氨基尿嘧啶开始,我们开发出了一种用于合成多种黄嘌呤的简便新方法。通过亚硝基化和还原反应生成相应的 5,6-二氨基脲嘧啶,并与羧酸缩合。在温和的条件下,可以选择性地在尿嘧啶环氮 N-1(对应于黄嘌呤 N-3)上对生成的酰胺进行烷基化。环闭合后,如果需要,在 7 位进行烷基化,可获得高产率的二取代黄嘌呤、三取代黄嘌呤或四取代黄嘌呤。可在 1 位引入敏感取代基,如丙-2-炔基。与制备黄嘌呤的标准程序相比,3-取代基的变化更为简便。