Ruthenium(II)-Catalyzed α-Fluoroalkenylation of Oxime Ethers with gem-Difluorostyrenes via C-H Activation and C-F Cleavage.

A novel route for ruthenium(II)-catalyzed α-fluoroalkenylation of oxime ethers with gem-difluorostyrenes via C-H activation and C-F cleavage has been developed for the first time. Notably, the alkenyl units of products exhibit exclusive Z-configuration. This reaction features a broad substrate scope and good functional group tolerance. A plausible reaction mechanism is confirmed by an available cycloruthenated intermediate. Besides, the O-methyl oximyl-directing group can be readily removed to access the α-fluoroalkenylated acetophenones.

Rhodium(III)-catalyzed C4-amidation of indole-oximes with dioxazolones via C-H activation.

A novel method for the Rh(iii)-catalyzed oxime-directed C-H amidation of indoles with dioxazolones has been developed. This strategy provides an exclusive site selectivity and the directing group can be easily removed. This transformation features a wide substrate scope, good functional group tolerance and excellent yields, and may serve as a significant tool to construct structurally diverse indole derivatives for the screening of potential pharmaceuticals in the future.

2-Amino-5,6-difluorophenyl-1H-pyrazole-Directed PdII Catalysis: Arylation of Unactivated ß-C(sp3)-H Bonds.

Palladium-catalyzed arylation of unactivated ß-C(sp3)-H bonds in carboxylic acid derivatives with aryl iodides is described for the first time using 2-amino-5,6-difluorophenyl-1H-pyrazole as an efficient and readily removable directing group. Two fluoro groups are installed at the 5- and 6-position of the anilino moiety in 2-aminophenyl-1H-pyrazole, clearly enhancing the directing ability of the auxiliary. In addition, the protocol employs Cu(OAc)2/Ag3PO4 (1.2/0.3) as additives, evidently reducing the stoichiometric amount of expensive silver salts. Furthermore, this process exhibits high ß-site selectivity, compatibility with diverse substrates containing α-hydrogen atoms, and excellent functional group tolerance.

Palladium-catalyzed direct mono-aroylation of O-arylmethyl and aryl-substituted acetoxime ethers.

An efficient palladium-catalyzed ortho-aroylation of O-arylmethyl and aryl-substituted acetoxime ethers has been developed; this method has high mono-site selectivity and does not require exogenous ligands. Under the direction of a simple exo-acetoxime auxiliary, a broad scope of masked arylmethyl alcohols and phenols as well as various aromatic aldehydes are compatible with this transformation, which probably follows a mechanistic pathway involving a six- or five-membered exo-cyclopalladated intermediate. The strategy can be expediently adopted to prepare synthetically valuable 1H-benzo[d][1,2]oxazines and benzo[d]isoxazoles. The directing group can be easily removed from the products to afford the functionalized diaryl ketones.

C-H Borylation of Diphenylamines through Adamantane-1-carbonyl Auxiliary by BBr3.

A method for ortho-C-H borylation of diphenylamines using BBr3 as the boron source has been reported. The noncatalytic adamantane-1-carbonyl directed reaction exhibited site exclusivity and good functional group tolerance. Generally, the borylation occurred at the more electron-rich aromatic ring and the borylated products could be converted to various useful intermediates. Besides, the derived arylation and removal of auxiliary of the product could be achieved in a one-pot fashion.

Tandem C-C/C-N Formation via Palladium-Catalyzed C-H Activation/Styrenation and Sequential Annulation of O-Methylketoxime with Styrenes.

A novel route for tandem C-C/C-N formation via palladium-catalyzed C-H activation/styrenation and annulation of O-methylketoxime with styrenes to synthesize benzothienopyridines and benzofuropyridines has been developed. Furthermore, the intermolecular alkenylation of the ketoxime with acrylates produces 3-alkenyl O-methylketoximes in good to excellent yields. The method features mild reaction conditions and good functional group tolerance, providing a direct approach for the preparation of fused heterocycles.