Copper‐Catalyzed C(sp3)‐H α‐Acetylation: Generation of Quaternary Centers

α‐substituted ketones are important chemical targets as synthetic intermediates as well as functionalities in in natural products and pharmaceuticals. We report the α‐acetylation of C(sp3)‐H substrates R‐H with arylmethyl ketones ArC(O)Me to provide α‐alkylated ketones ArC(O)CH2R at RT with tBuOOtBu as oxidant via copper(I) β‐diketiminato catalysts. Proceeding via alkyl radicals R•, this method enables α‐substitution with bulky substituents without competing elimination that occurs in more traditional alkylation reactions between enolates and alkyl electrophiles. DFT studies suggest the intermediacy of copper(II) enolates [CuII](CH2C(O)Ar) that capture alkyl radicals R• to give R‐CH2C(O)Ar under competing dimerization of the copper(II) enolate to give the 1,4‐diketone ArC(O)CH2CH2C(O)Ar.