Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA.
Chem Commun (Camb). 2020 Nov 11;56(87):13287-13300. doi: 10.1039/d0cc05554a. Epub 2020 Oct 5.
Allylic substitution, pioneered by the work of Tsuji and Trost, has been an invaluable tool in the synthesis of complex molecules for decades. An attractive alternative to allylic substitution is the direct functionalization of allylic C-H bonds of unactivated alkenes, thereby avoiding the need for prefunctionalization. Significant early advances in allylic C-H functionalization were made using palladium catalysis. However, Pd-catalyzed reactions are generally limited to the functionalization of terminal olefins with stabilized nucleophiles. Insights from Li, Cossy, and Tanaka demonstrated the utility of RhCp catalysts for allylic functionalization. Since these initial reports, a number of key intermolecular Co-, Rh-, and Ir-catalyzed allylic C-H functionalization reactions have been reported, offering significant complementarity to the Pd-catalyzed reactions. Herein, we report a summary of recent advances in intermolecular allylic C-H functionalization via group IX-metal π-allyl complexes. Mechanism-driven development of new catalysts is highlighted, and the potential for future developments is discussed.
烯丙基取代反应由 Tsuji 和 Trost 的工作开创，几十年来一直是合成复杂分子的宝贵工具。烯丙基 C-H 键的直接官能化是烯丙基取代反应的一种有吸引力的替代方法，从而避免了预官能化的需要。使用钯催化取得了烯丙基 C-H 官能化的早期重大进展。然而，Pd 催化的反应通常限于用稳定的亲核试剂对末端烯烃进行官能化。Li、Cossy 和 Tanaka 的研究结果证明了 RhCp 催化剂在烯丙基官能化中的实用性。自这些最初的报道以来，已经报道了许多关键的 Co、Rh 和 Ir 催化的烯丙基 C-H 官能化反应，为 Pd 催化的反应提供了重要的补充。本文综述了通过第 IX 族金属π-烯丙基配合物进行的分子间烯丙基 C-H 官能化的最新进展。重点介绍了基于机理的新型催化剂的开发，并讨论了未来发展的潜力。
