Ni-Catalyzed Direct Carboxylation of an Unactivated C–H Bond with CO2

The transition-metal-catalyzed direct carboxylation of an unactivated C–H bond is rarely reported, and no example of catalysis using abundant and cheap nickel has been reported. In this work, the first Ni-catalyzed direct carboxylation of an unactivated C–H bond under an atmospheric pressure of CO 2 is reported. This method affords moderate to high carboxylation yields of various methyl carboxylates under mild conditions. Preliminary mechanistic studies reveal that a Ni(0)–Ni(II)–Ni(I) catalytic cycle may be involved in this reaction.