Palladium-Catalyzed Carbon-Carbon Bond-Forming Reactions with Unactivated Alkyl Electrophiles

摘要

I. Cross-Coupling Reactions with Alkyl Electrophiles An overview of the application of alkyl electrophiles in cross-coupling reactions is presented, highlighting the importance of this reactivity and challenges associated therein. Recent advances in alkyl cross-coupling are discussed, from both a process development and mechanistic perspective, to describe the current state of the field. Advances in hybrid organometallic-radical reactivity are also considered, with particular focus on its application in alkyl cross-coupling and perspective on mechanistic analysis.;II. Palladium-Catalyzed Ring-Forming Aromatic C-H Alkylation A palladium-catalyzed, intramolecular aromatic C-H alkylation with unactivated alkyl halides is described. This process is successful with both iodides and bromides, including those with ?-hydrogen atoms present. It also tolerates both electron-rich and electron-poor aromatic rings, as well as heteroaromatic substrates. The mild, palladium-catalyzed approach displays compatibility with a diverse range of functional groups, including those which are base- or nucleophile-sensitive. A mechanistic investigation is also presented, suggesting the presence of radical intermediates.;III. A Versatile, Palladium-Catalyzed Approach to Alkene-Alkyl Halide Coupling A method for the palladium-catalyzed coupling of alkyl halides with alkenes is presented. Reaction conditions determine whether the end product retains the alkyl halide moiety in an atom-transfer radical cyclization (ATRC) reaction, or if the alkene component is restored, affecting a formal Heck-type transformation. The manifold is capable of performing both transformations with unactivated alkyl bromides and a variety of terminal, di- and tri-substituted alkenes under argon atmosphere. It also enables formation of both 5- and 6-membered rings. A mechanistic investigation of this reaction is presented, which suggests the operation of a catalytic, hybrid organometallic-radical process.