Palladium‐Catalyzed Pyrazole‐Directed sp 3 C−H Bond Arylation for the Synthesis of β‐Phenethylamines

Site-Selective Pd-Catalyzed C(sp3 )-H Arylation of Heteroaromatic Ketones

A ligand-controlled site-selective C(sp3 )-H arylation of heteroaromatic ketones has been developed using Pd catalysis. The reaction occurred selectively at the α- or β-position of the ketone side-chain. The switch from α- to β-arylation was realized by addition of a pyridone ligand. The α-arylation process showed broad scope and high site- and chemoselectivity, whereas the β-arylation was more limited. Mechanistic investigations suggested that α-arylation occurs through C-H activation/oxidative addition/reductive elimination whereas β-arylation involves desaturation and aryl insertion.

Iridium-Catalyzed Regio- and Enantioselective Borylation of Unbiased Methylene C(sp3 )-H Bonds at the Position β to a Nitrogen Center

Reported herein is the pyrazole-directed iridium-catalyzed enantioselective borylation of unbiased methylene C-H bonds at the position β to a nitrogen center. The combination of a chiral bidentate boryl ligand, iridium precursor, and pyrazole directing group was responsible for the high regio- and enantioselectivity observed. The method tolerated a vast array of functional groups to afford the corresponding C(sp³ )-H functionalization products with good to excellent enantioselectivity.