Until now, the selective (hetero)­aryl C–H alkylation without the assistance of directing groups or preinstallation of functionalities still remains a highly challenging goal. Herein, by developing acid-resistant multispherical cavity carbon-supported cobalt oxide nanocatalysts (CoO x /MSCC) and a hydrogen transfer-mediated activation mode for nonactivated N-heteroaromatics, we present a direct reductive quinolyl and isoquinolyl β-C–H alkylation with various aldehydes as the alkylating agents. The catalytic transformation features broad substrate scope, good functional tolerance, use of Earth-abundant and reusable cobalt catalysts, and no need for prefunctionalizations, demonstrating that the developed nanocatalysts enable one to directly functionalize inert N-heteroaryl systems that are difficult to realize by organometallic complexes.

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