Internal Azomethine Ylide Cycloaddition Methodology for Access to the Substitution Pattern of Aziridinomitosene A
作者:Drew R. Bobeck、Don L. Warner、Edwin Vedejs
DOI:10.1021/jo7013559
日期:2007.10.1
participate in the internal 2 + 3 cycloaddition with azomethine ylides generated by treatment of oxazolium salts with cyanide ion. Starting from oxazole 26, a sequence of N-methylation, cyanide addition, and electrocyclic ring opening of a 4-oxazoline intermediate affords the indoloquinone 31 in a one-pot process. A similar reaction from the protected alkynol derivative 25 affords the sensitive, but
高度取代的束缚炔偶极亲和体参与与通过用氰化物离子处理恶唑鎓盐生成的甲亚胺叶立德的内部2+3环加成。从恶唑26开始,经过一系列N-甲基化、氰化物加成和4-恶唑啉中间体的电环开环,在一锅法中得到吲哚醌31 。由受保护的炔醇衍生物25进行类似的反应,得到敏感但可分离的烯酮32,随后氧化得到31和脱保护的醌醇34。还证明了通过从43或46形成分子内恶唑鎓盐的相关偶氮甲碱环加成方法,并允许合成醌45和具有氮丙啶基核糖烯 A 取代模式的衍生结构。在没有氮丙啶裂解的情况下,无法实现N-三苯甲基保护基团的去除。