Kotov Vasily, Scarborough Christopher C, Stahl Shannon S
Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA.
Inorg Chem. 2007 Mar 19;46(6):1910-23. doi: 10.1021/ic061997v.
Palladium-catalyzed methods for the aerobic oxidative coupling of alkenes and oxygen nucleophiles (e.g., water and carboxylic acids) have been known for nearly 50 years. The present account summarizes our development of analogous aerobic oxidative amination reactions, including the first intermolecular aza-Wacker reactions compatible with the use of unactivated alkenes. The reactions are initiated by intra- or intermolecular aminopalladation of the alkene. The resulting alkylpalladium(II) intermediate generally undergoes beta-hydride elimination to produce enamides or allylic amide products, but in certain cases, the Pd-C bond can be trapped to achieve 1,2-difunctionalization of the alkene, including carboamination and aminoacetoxylation. Mechanistic studies have provided a variety of fundamental insights into the reactions, including the effect of ancillary ligands on palladium catalysts, the origin of the Brønsted-base-induced switch in regioselectivity in the oxidative amination of styrene, and evidence that both cis- and trans-aminopalladations of alkenes are possible. Overall, these reactions highlight the potential utility of an "organometallic oxidase" strategy for the selective aerobic oxidation of organic molecules.
钯催化的烯烃与氧亲核试剂（如水和羧酸）的需氧氧化偶联方法已经存在了近50年。本报告总结了我们对类似需氧氧化胺化反应的研究进展，包括首次实现的与未活化烯烃兼容的分子间氮杂瓦克反应。这些反应由烯烃的分子内或分子间氨基钯化引发。生成的烷基钯（II）中间体通常会发生β-氢消除反应，生成烯酰胺或烯丙基酰胺产物，但在某些情况下，钯-碳键可以被捕获，从而实现烯烃的1,2-双官能化，包括碳胺化和氨基乙酰氧基化。机理研究为这些反应提供了多种基本见解，包括辅助配体对钯催化剂的影响、布朗斯特碱诱导的苯乙烯氧化胺化区域选择性转变的起源，以及烯烃的顺式和反式氨基钯化均有可能的证据。总体而言，这些反应突出了“有机金属氧化酶”策略在有机分子选择性需氧氧化中的潜在应用价值。
