School of Chemistry, University of Manchester , Oxford Road, Manchester M13 9PL, United Kingdom.
J Am Chem Soc. 2017 Aug 23;139(33):11527-11536. doi: 10.1021/jacs.7b05155. Epub 2017 Aug 8.
Constructing products of high synthetic value from inexpensive and abundant starting materials is of great importance. Aryl iodides are essential building blocks for the synthesis of functional molecules, and efficient methods for their synthesis from chemical feedstocks are highly sought after. Here we report a low-cost decarboxylative iodination that occurs simply from readily available benzoic acids and I. The reaction is scalable and the scope and robustness of the reaction is thoroughly examined. Mechanistic studies suggest that this reaction does not proceed via a radical mechanism, which is in contrast to classical Hunsdiecker-type decarboxylative halogenations. In addition, DFT studies allow comparisons to be made between our procedure and current transition-metal-catalyzed decarboxylations. The utility of this procedure is demonstrated in its application to oxidative cross-couplings of aromatics via decarboxylative/C-H or double decarboxylative activations that use I as the terminal oxidant. This strategy allows the preparation of biaryls previously inaccessible via decarboxylative methods and holds other advantages over existing decarboxylative oxidative couplings, as stoichiometric transition metals are avoided.
从廉价且丰富的起始原料构建具有高合成价值的产物非常重要。芳基碘化物是合成功能分子的重要构建模块，因此人们迫切需要从化学原料高效合成芳基碘化物的方法。在此，我们报道了一种从易得的苯甲酸和 I 简单发生的廉价脱羧碘化反应。该反应具有可扩展性，并且对其反应的范围和稳健性进行了彻底的考察。机理研究表明，该反应不是通过自由基机制进行的，这与经典的 Hunsdiecker 型脱羧卤化反应不同。此外，DFT 研究允许对我们的方法与当前过渡金属催化的脱羧反应进行比较。该方法的实用性通过其在通过脱羧/C-H 或双脱羧活化的芳族化合物的氧化交叉偶联中的应用得到了证明，其中 I 用作末端氧化剂。该策略允许通过脱羧方法以前无法制备的联芳烃的制备，并具有优于现有脱羧氧化偶联的其他优势，因为避免了化学计量的过渡金属。
