The textbook alkene halogenation reaction establishes straightforward access to vicinal dihaloalkanes. However, robust catalytic methods to perform dihalogenation in a stereoselective manner are lacking, despite the ubiquity of contiguous halogen-bearing stereocentres in natural products, bioactive and pharmaceutical molecules. Here we show that a urea directing moiety judiciously installed on alkenes could anchor the halogen nucleophiles and thus circumvent the regioselectivity issue in this transformation. Additionally, common alkali halides could be used as halogenating reagents. Our organocatalytic strategy granted modular and streamlined access to diverse homo-/hetero-dihalogenation products with exquisite stereo- and regiocontrol, irrespective of the alkene geometry. Pseudoenantiomeric catalysts could relay chiral information in bromofluorination of isomeric alkenes, providing unified access to the full complement of stereoisomers. Extending this synthetic tactic to alkynes culminated in their atroposelective dihalogenation affording axially chiral alkenes.

教科书烯烃卤化反应建立了对连位二卤代烷烃的直接访问。然而，尽管在天然产物、生物活性和药物分子中普遍存在连续的含卤素立体中心，但仍缺乏以立体选择性方式进行二卤化的稳健催化方法。在这里，我们表明，明智地安装在烯烃上的脲导向部分可以锚定卤素亲核试剂，从而避免这种转化中的区域选择性问题。此外，常见的碱金属卤化物可用作卤化试剂。我们的有机催化策略允许模块化和流线型地访问各种均-/杂-二卤化产品，具有精致的立体和区域控制，而与烯烃几何形状无关。假对映异构体催化剂可以在异构烯烃的溴氟化反应中传递手性信息，从而提供对完整立体异构体的统一访问。将这种合成策略扩展到炔烃，最终导致它们的转位选择性二卤化反应，得到轴向手性烯烃。