Alkylation reactions represent an important organic transformation to form C-C bonds. In addition to conventional approaches with alkyl halides or sulfonates as alkylating agents, the use of unactivated olefins for alkylations has become attractive from both cost and sustainability viewpoints. This Review summarizes transition-metal-catalyzed alkylations of various carbon-hydrogen bonds (addition of C-H bonds across olefins) using regular olefins or 1,3-dienes up to May 2016. According to the mode of activation, the Review is divided into two sections: alkylation via C-H activation and alkylation via olefin activation.

Organotransition metal complexes capable of forming metalloradicals have been an intriguing subject of study for the past fifty years. Of these, rhodium porphyrin complexes have proven particularly interesting due to their straightforward synthesis and unique reactivity; indeed, these complexes are responsible for some highly influential transformations of organic compounds, including rare C-H and C-C bond activations. The complexity and selectivity of rhodium porphyrins has been attractive for catalytic transformations, with specific interest in their usage for selective carbon monoxide reduction for fuel cell applications. This review will highlight historical and modern syntheses of rhodium porphyrins, as well as their respective reactions with small molecules and applications therein. The discussion will be limited to rhodium porphyrins consisting of four pyrrolic rings bridged with four methine units.

Here, a palladium-catalyzed functionalization of unactivated sp(3) C-H bonds with internal alcohol nucleophiles is described. Directed by an oxime-masked alcohol, annulation chemoselectively occurs at the β position, leading to a range of aliphatic cyclic ethers with four- to seven-membered rings. Tethered primary, secondary, and tertiary free hydroxyl groups can all react to give the corresponding cyclized products. In addition, benzyl and silyl protected alcohols can also be directly coupled. An sp(3) C-H activation/intramolecular SN2 pathway was proposed.

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Amino alkylation of technical lignins via the Mannich reaction can be used as an analytical derivatization technique, but also in an applied manner to improve kraft lignin hydrophilicity or metal...