Nickel-Catalyzed Site-Selective C3–H Functionalization of Quinolines with Electrophilic Reagents at Room Temperature

Herein,
we disclose a mild and versatile nickel-catalyzed method
for exclusive C3-selective thioetherification, alkylation, arylation,
acylation, and phosphorylation of quinolines with a variety of electrophiles.
Unactivated quinolines can be functionalized without directing groups
at room temperature. Control experiments indicated that quinolines
underwent 1,4-addition with nickel hydride species generated from
β-H elimination of alkyl nickel intermediates to produce 1,4-dihydroquinolines,
which further went through subsequent nucleophilic attack to external
electrophiles and oxidative aromatization to generate C3–H-functionalized
products.