Synthesis of sugar-modified analogs of bredinin (mizoribine), a clinically useful immunosuppressant, by a novel photochemical imidazole ring-cleavage reaction as the key step
The imidazole nucleosidebredinin (mizoribine) is a clinically useful immunosuppressant. Derivatization of bredinin by the usual nucleoside chemistry is often troublesome due to the unusual zwitterionic structure of the basemoiety. We achieve the synthesis of 5′-modified analogs of bredinin via a novel photochemical imidazole ring-cleavage reaction as the key step. When a solution of 2′,3′-O-isopropylidenebredinin
咪唑核苷bredinin(咪唑啉碱)是一种临床上有用的免疫抑制剂。 衍生化 通常的bredinin 核苷由于碱基部分的不寻常的两性离子结构,化学反应通常很麻烦。我们通过一种新型的光化学咪唑环裂解反应实现了bredinin 5'-修饰类似物的合成,这是关键步骤。当用高压汞灯照射2',3'- O-异亚苄基内酯5在0.1 M AcOH中的溶液时,发生咪唑环裂解反应,以71%的产率得到2-氨基丙二酰胺核糖苷衍生物16。适当修饰16的5'-位置,然后与(EtO)3 CH缩合以重建咪唑随后是碱基部分。使用这种咪唑环裂解重建策略,一些生物学上重要的5'-修饰的布雷青霉素类似物,即,将5'-磷酸2中,5'-脱氧衍生物3,和5'- Ò -aminopropylcarbamate 4被有效地合成。