Nickel-catalyzed regioselective arylation of aromatic amides with aryl iodides enabled by an N,O-bidentate directing group

A bidentate directing group enabled ortho-arylation of C(sp²)–H bonds in aromatic carboxamides with aryl iodides under nickel-catalysis was developed.

Copper-catalyzed peri-selective direct sulfenylation of 1-naphthylamines with disulfides

A copper-catalyzed peri-selective direct C–H sulfenylation of 1-naphthylamines with disulfides was developed.

Computational Study of Ni-Catalyzed C-H Functionalization: Factors That Control the Competition of Oxidative Addition and Radical Pathways

The mechanisms of Ni-catalyzed C-H arylation, alkylation, and sulfenylation with N,N-bidentate directing groups are investigated using density functional theory (DFT) calculations. While the C-H cleavage occurs via the concerted metalation-deprotonation (CMD) mechanism in all types of reactions, the subsequent C-C and C-X bond formation steps may occur via either oxidative addition to form a Ni(IV) intermediate or radical pathways involving Ni(III) complexes generated from homolytic dissociation of disulfides/peroxides or halide-atom transfer from alkyl halides. DFT calculations revealed that radical mechanisms are preferred in reactions with sterically hindered coupling partners with relatively low bond dissociation energies (BDE) such as dicumyl peroxide, heptafluoroisopropyl iodide and diphenyl disulfide. In contrast, these radical processes are highly disfavored when generating unstable phenyl and primary alkyl radicals. In such cases, the reaction proceeds via an oxidative addition/reductive elimination mechanism involving a Ni(IV) intermediate. These theoretical insights into the substrate-controlled mechanisms in the C-H functionalizations were employed to investigate a number of experimental phenomena including substituent effects on reactivity, chemo- and regioselectivity and the effects of oxidant in the intermolecular oxidative C-H/C-H coupling reactions.

Expeditious and Solvent-Free Nickel-Catalyzed C-H Arylation of Arenes and Indoles

An efficient solvent-free nickel-catalyzed method for C-H bond arylation of arenes and indoles has been developed, which proceeds expeditiously through chelation assistance. The reaction is highly selective for mono-arylation and tolerates sensitive and structurally diverse functionalities, such as halides, ethers, amines, indole, pyrrole and carbazole. This reaction represents the first example of a nickel-catalyzed C-H arylation by monochelate assistance and symbolizes a rare precedent in solvent-free C-H arylation. Mechanistic investigations by various controlled reactions, kinetic studies, and deuterium labeling experiments suggest that the arylation follows a single electron transfer (SET) pathway involving the turnover-limiting C-H nickelation process.

Palladium(ii)-catalyzed ortho-C–H olefination of phenylalanine and phenylethylamine derivatives directed by removable picolinamide group

Palladium-catalyzed ortho-C–H olefination of phenylalanine and phenylethylamine derivatives assisted by a removable picolinamide group has been achieved.

Cu(ii)-catalyzed C6-selective C–H thiolation of 2-pyridones using air as the oxidant

Cu(II)-catalyzed C6-selective C–H thiolation of 2-pyridones with aryl and alkyl disulfides to provide functional thioethers has been achieved.

Palladium-catalysed direct thiolation and selenation of aryl C–H bonds assisted by directing groups

Recent advances on transition-metal-catalyzed direct chalcogenation of C–H bonds with disulfides and diselenides are summarized.

Palladium(II)-catalyzed directed trifluoromethylthiolation of unactivated C(sp³)-H bonds

The synthesis of trifluoromethylthiolated aliphatic acid derivatives by Pd-catalyzed C(sp(3))-H bond functionalization was developed. Using a bidentate directing group, the direct and selective introduction of a SCF3 moiety was possible on a range of amides with remarkable selectivity for C(sp(3))-centers with an electrophilic SCF3 source and pivalic acid as an additive. This work constitutes an example of the unactivated C(sp(3))-SCF3 bond formation by C-H activation offering a new access to relevant molecules.

Copper-mediated thiolation of carbazole derivatives and related N-heterocycle compounds

Cu-mediated direct thiolation of carbazole derivatives with disulfides via C–H bond cleavage to give diaryl and alkyl aryl sulfides which easily extends to the synthesis of thioethers with a benzo[h]quinolone, 2-phenylquinoline or indole moiety in satisfactory yields.

Nickel-catalyzed direct thiolation of unactivated C(sp3)–H bonds with disulfides

The first nickel-catalyzed thiolation of unactivated C(sp³)–H bonds with disulfides is described.

Nickel-catalyzed thiolation of unactivated aryl C–H bonds: efficient access to diverse aryl sulfides

A nickel-catalyzed thiolation of unactivated C(sp²)–H bonds with disulfides employing the PIP directing group was described. This process uses a catalytic nickel catalyst and no metallic oxidants or cocatalysts are required. Moreover, the reaction tolerates various important functional groups and heteroarenes.

Nickel-catalyzed directed sulfenylation of sp2 and sp3 C–H bonds

Directed sulfenylation of both sp² and sp³ C–H bonds was achieved through nickel catalyzed directed C–S bond formation, giving the desired product in good to excellent yield (up to 90%).