A novel and facile C-H bond fluorination proceeds under remarkably mild conditions (close to room temperature in most cases). Both aromatic and olefinic C(sp(2))-H bonds with a wide range of electronic properties are selectively fluorinated in the presence of a catalytic amount of simple, cheap, and nontoxic nitrate as the promoter. A Pd(II)/Pd(IV) catalytic cycle that is initiated by an in situ generated cationic [Pd(NO3)](+) species was proposed based on preliminary mechanistic studies.

A novel Pd(OAc)2-NFSI-TFA system was developed for the highly selective ortho-monofluorination directed by diverse aryl-N-heterocyclic directing groups e.g., quinoxaline, pyrazole, benzo[d]oxazole, and pyrazine derivatives. A Pd(II/IV) catalytic cycle was proposed based on the ESI-MS/MS studies.

The exo-selective C–H cycloaddition of imidazoles to 1,1-disubstituted alkenes has been achieved for the first time by using half-sandwich scandium catalysts. A wide range of imidazole compounds bearing various 1,1-disubstituted aliphatic alkenes, styrenes, dienes, and enynes have been selectively converted in high yields to the corresponding bicyclic imidazole derivatives bearing β-all-carbon-substituted quaternary stereocenters. By using a chiral half-sandwich scandium catalyst, the asymmetric exo-selective cyclization has also been achieved with a high level of enantioselectivity.

A fast and site-selective biaryl synthesis via dehydrogenative C−H/C−H arylation in a ball mill was developed. In this paper, both electron-deficient oximes and electron-rich anilides quickly and under mild conditions provided arylation with various arenes to give the biaryl products in high-level selectivity. Given the solventless mechanochemical conditions, the transformation obviated the use of large amounts of arene coupling partners as solvents and allowed utilization of more-complicated and more-expensive arenes as coupling partners, which may dramatically enhance the application prospect of the C−H/C−H arylation strategy.

The enantioselective C−H alkenylation of ferrocenes with alkynes is, in principle, a straightforward and atom-efficient route for the construction of planar-chiral ferrocene scaffolds bearing alkene functionality but has remained scarcely explored to date.Here we report for the first time the highly enantioselective C−H alkenylation of quinoline-and pyridine-substituted ferrocenes with alkynes by a half-sandwich scandium catalyst. This protocol features broad substrate scope, high enantioselectivity, and 100% atom efficiency, selectively affording a new family of planar-chiral ferrocenes bearing N/alkene functionalities. The mechanistic details have been clarified by DFT analyses. The use of a quinoline/alkene-functionalized ferrocene product as a chiral ligand for asymmetric catalysis is also demonstrated.