State Key Laboratory of Chirosciences and Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (Hong Kong), Fax: (+852) 2364-9932.
Chemistry. 2013 Nov 18;19(47):15802-14. doi: 10.1002/chem.201301583. Epub 2013 Oct 25.
Transition-metal-free cross-coupling reactions have been a hot topic in recent years. With the aid of a radical initiator, a number of unactivated arene C-H bonds can be directly arylated/functionalized by using aryl halides through homolytic aromatic substitution. Commercially available or specially designed promoters (e.g. diamines, diols, and amino alcohols) have been used to make this synthetically attractive method viable. This protocol offers an inexpensive, yet efficient route to aromatic C-C bond formations since transition metal catalysts and impurities can be avoided by using this reaction system. In this article, we focus on the significance of the reaction conditions (e.g. bases and promoters), which allow this type of reaction to proceed smoothly. Substrate scope limitations and challenges, as well as mechanistic discussion are also included.
近年来，无过渡金属的交叉偶联反应一直是一个热门话题。在自由基引发剂的帮助下，许多未活化的芳基 C-H 键可以通过均裂芳香取代作用，直接用芳基卤化物进行芳基化/官能化。商业上可获得的或专门设计的促进剂（例如二胺、二醇和氨基醇）已被用于使这种具有吸引力的合成方法可行。由于可以避免使用该反应体系中的过渡金属催化剂和杂质，因此该方案为芳族 C-C 键形成提供了一种廉价而有效的途径。在本文中，我们重点介绍了使此类反应顺利进行的反应条件（例如碱和促进剂）的重要性。还包括底物范围的限制和挑战以及机理讨论。
