过渡金属催化的C—H键官能团化是直接构建C—C或C—X键的一个高效的方法,但这类反应大多需要外加当量或过量的氧化剂来完成催化循环.使用氧化型导向基,也就是在导向基中引入某些特殊的基团充当内氧化剂,可以避免外加氧化剂,简化反应体系,提高反应效率.近年氧化型导向基结构日趋丰富,参与的反应类型也呈现出多样化.利用氧化型导向基策略可以在无外加氧化剂条件下合成各种杂环或官能团化产物.
Transition-metal catalyzed C—H functionalization is a straightforward and efficient way to construct C—C and C—X bonds. However, these transformations usually require stioichiometric or excess amount of external oxidants to oxidize low valent metal and regenerate the active catalytic species. The use of the oxidizing directing group, which contains some special group acting as the internal oxidant, can avoid the troubles arousing from the external oxidants and make the reaction process more simple and efficient. Recently, increasing number of novel oxidizing directing groups have been designed and diverse kinds of reactions have been developed. This approach can be used to synthesize kinds of heterocyles or highly functionalized products under external oxidant free conditions.