Stereoselective Synthesis of Trisubstituted Olefins by a Directed Allylic Substitution Strategy
作者:Yvonne Schmidt、Bernhard Breit
DOI:10.1002/chem.201100843
日期:2011.10.10
α‐methylene aldehydes. Addition of an organometallic reagent and introduction of the o‐DPPB group by esterification was followed by the o‐DPPB‐directed copper‐mediated allylic substitution with a Grignard reagent to furnish stereodefined trisubstituted olefins. Additionally, incorporation of a stereocenter from the chiral pool allowed the preparation of an enantiomerically pure olefin that bore three alkyl
提出了立体选择性合成三取代烯烃的新方法。使用邻二苯膦基苯甲酸酯(o- DPPB)作为直接离去基团,用Grignard试剂进行铜介导的烯丙基取代可实现多种E烯烃的立体选择性构建,而无需相邻的吸电子基团。我们针对三取代烯烃的模块化三步方法始于双生α-亚甲基醛。在添加有机金属试剂并通过酯化引入o -DPPB基团后,再进行o用Grignard试剂在DPPB导向的铜介导的烯丙基取代中提供立体定义的三取代烯烃。另外,通过从手性池中引入立体中心,可以制备对映体纯的烯烃,该烯烃具有高E / Z选择性的三个烷基取代基。