作者:Xiaodong Lin、Robert W. Kavash、Patrick S. Mariano
DOI:10.1021/jo961179s
日期:1996.1.1
interrelated strategies for the synthesis of members of the cephalotaxus alkaloid family have culminated in a concise route for the preparation of the parent member cephalotaxine (1). As part of efforts exploring the use of an SET-promoted photocyclization reaction of aryl-substituted silylallyliminium salts to generate the spirocyclic DE unit of the target, we noted that attempts to generate the pentacyclic
对两种相互关联的头孢类生物碱家族成员合成策略的研究最终以简洁的方法制备了亲本头孢他辛(1)。作为探索使用SET促进的芳基取代的甲硅烷基烯丙二胺盐的光环化反应以生成靶标的螺环DE单元的一部分,我们注意到,通过烯醇酯20的脱酰作用生成五环氨基酮23的尝试导致了产生23和大环氨基烯酮24的混合物。显示23和24之间存在快速平衡,有利于后者的开环形式。这与desmethylcephalotaxinone(22)的行为相反,desmethylcephalotaxinone(22)是几种早期头孢他辛合成中的关键晚期中间体,已知以闭环形式存在。