Transition-Metal-Free Transfer Hydrohalogenation

小分子从一个分子到另一个分子的转移最近变成了一个新兴领域。通过这种方式，可以绕过气体和潜在危险化学品的处理。本实验室引入了充分取代的环己-1，4-二烯作为氢硅烷和二氢的替代物，分别进行了Lewis酸催化的硅氢转移氢化和烯烃的加氢反应。实现转移氢卤化的相关无机酸替代品是非常可取的，但在化学上不稳定，通常在芳构化的同时迅速消除HX。我们现在已经设计了一种新型的转移剂，同样是基于环己-1，4-二烯平台，它的化学稳定性很强，从而允许HX的受控释放以及HX在碳-碳多键上的转移。该过程是质子催化的，因此不同于早期的无过渡金属的转移反应。在这个项目中，我们将开发合成有用的低分子代用品，主要是X=I，Br，Cl，甚至F，并将这些代用品应用于氢卤化反应。还预计将扩大这一转移硅烷卤化的战略。

The transfer of small molecules from one molecule to another recently turned into an emerging area. By this, the handling of gaseous and potentially dangerous chemicals is bypassed. Our laboratory introduced adequately substituted cyclohexa-1,4-dienes as surrogates of hydrosilanes and dihydrogen, and these engage in Lewis acid-catalyzed transfer hydrosilylation and hydrogenation of alkenes, respectively. Related surrogates of mineral acids to achieve transfer hydrohalogenation are highly desirable but not chemically stable, usually rapidly eliminating HX concomitant with aromatization. We have now designed a new type of transfer reagent, again based on the cyclohexa-1,4-diene platform, that is chemically robust, thereby allowing for controlled release of HX as well as transfer of HX onto carbon-carbon multiple bonds. The process is proton-catalyzed and, as such, different from the earlier transition-metal-free transfer reactions. Within this project, we will develop synthetically useful low-molecular-weight surrogates, predominantly for X = I, Br, Cl and even F, and apply these to transfer hydrohalogenation. Expansion of this strategy to transfer silylhalogenation is also anticipated.