本文报道了新的Rh和Pd催化的咪唑衍生物与单取代的Allenes的区域发散和立体选择性分子间偶联反应。使用Rh I / Josiphos系统,可以获得完美的区域选择性和高对映体过量,而Pd II / dppf系统则可提供具有高区域选择性和高E / Z选择性的线性产物。该方法允许原子经济地合成有价值的支链和线性烯丙基咪唑衍生物。
Iridium-Catalyzed Kinetic Asymmetric Transformations of Racemic Allylic Benzoates
作者:Levi M. Stanley、Chen Bai、Mitsuhiro Ueda、John F. Hartwig
DOI:10.1021/ja103779e
日期:2010.7.7
Versatile methods for iridium-catalyzed, kinetic asymmetric substitution of racemic, branched allylic esters are reported. These reactions occur with a variety of aliphatic, aryl, and heteroaryl allylic benzoates to form the corresponding allylic substitution products in high yields (74-96%) with good to excellent enantioselectivity (84-98% ee) with a scope that encompasses a range of anionic carbon and heteroatom nucleophiles. These kinetic asymmetric processes occur with distinct stereochemical courses for racemic aliphatic and aromatic allylic benzoates, and the high reactivity of branched allylic benzoates enables enantioselective allylic substitutions that are slow or poorly selective with linear allylic electrophiles.