Palladium-Catalyzed Radical-Type Transformations of Alkyl Halides

Palladium-catalyzed cross-coupling reactions have been developed for decades as useful methods in organic synthesis. Compared to aryl and alkenyl halides, alkyl halides are more challenging to be applied in cross-coupling reactions. This mainly arises from the difficulty in oxidative addition of alkyl halides to palladium catalyst, sluggish reductive elimination and competitive side reactions, such as beta-H elimination and protonation, of the resulting alkylpalladium intermediates. These challenges have partly been overcome with the significant development of novel palladium catalysis involving single election transfer. A variety of cross couplings of alkyl halides have been developed. In this review the recent palladium-catalyzed radical alkylation using alkyl halides with the order of different types of coupling partners is summarized.