A new synthetic approach to 8-chloroflavins and their conversion into 8-(substituted-amino)flavins.
作者:FUMIO YONEDA、KAZUO SHINOZUKA、KEIKO HIROMATSU、RYOKO MATSUSHITA、YOSHIHARU SAKUMA、MASATOMO HAMANA
DOI:10.1248/cpb.28.3576
日期:——
Treatment of 5-nitro-6-(N-substituted-anilino) uracils (I) with the Vilsmeier reagent (dimethylformamide-phosphorus oxychloride) gave the corresponding 8-chloroisoalloxazines (8-chloroflavins) (II) in a single step. The conversion of I into II probably proceeds via the intermediate formation of the corresponding isoalloxazine 5-oxides (flavin 5-oxides). In fact, treatment of flavin 5-oxides with the Vilsmeier reagent also gave the 8-chloroflavins. Under the same conditions, 7-bromoflavin 5-oxides did not give the corresponding 7-bromo-8-chloroflavins, but the deoxygenated 7-bromoflavins were obtained. In this case, the Vilsmeier reagent acted as a reducing agent as well as a dehydrating and chlorinating agent. The 8-chloroflavins were converted into 8-(substituted-amino) flavins by treatment with appropriate amines.
将5-硝基-6-(N-取代芳基氨基)尿嘧啶(I)与维尔斯梅尔试剂(N,N-二甲基甲酰胺-磷酸氧氯)反应,可以一步得到相应的8-氯异黄素(8-氯黄素)(II)。I转化为II可能经过相应的异黄素5-氧化物(黄素5-氧化物)的中间体形成。事实上,将黄素5-氧化物与维尔斯梅尔试剂反应也能得到8-氯黄素。在相同条件下,7-溴黄素5-氧化物未能得到相应的7-溴-8-氯黄素,而是获得了去氧化的7-溴黄素。在这种情况下,维尔斯梅尔试剂既充当了还原剂,又起到了脱水和氯化剂的作用。8-氯黄素通过与适当的胺反应转化为8-(取代氨基)黄素。