Design and synthesis of a new polymer-supported Evans-type oxazolidinone: an efficient chiral auxiliary in the solid-phase asymmetric alkylation reactions
作者:Tomoya Kotake、Yoshio Hayashi、S. Rajesh、Yoshie Mukai、Yuka Takiguchi、Tooru Kimura、Yoshiaki Kiso
DOI:10.1016/j.tet.2005.01.135
日期:2005.4
ee) and moderate to good overall yield (up to 70%, for 3 steps), which were comparable to those of the conventional solution-phase methods. Furthermore, recovery and recycling of the polymer-supported chiral auxiliary were successfully achieved without decreasing the stereoselectivity of the product. Therefore, this is the first successful example that the solid-phase Evans' asymmetric enolate-alkylation
Wang树脂支撑的Evans手性助剂(23)是基于一种新颖的聚合物固定策略设计的,该策略利用了恶唑烷酮环的5位,并开发了适用于一天之内多克制备的新合成路线。23衍生的N上的固相Evans不对称烷基化-酰酰亚胺树脂和随后的氢过氧化物锂介导的化学选择性水解,可提供所需的高立体选择性(最高97%ee)和中等至良好的总收率(3步最高可达70%)的相应α-支链羧酸。与传统的固溶相方法相比。此外,在不降低产物的立体选择性的情况下,成功地实现了聚合物负载的手性助剂的回收和再循环。因此,这是在固体载体上有效地进行固相埃文斯不对称烯醇烷基化的第一个成功实例,并且得出的结论是,通过恶唑烷酮环的5-位与固体载体的连接是固相埃文斯手性助剂的理想策略。