Synthesis of α-Alkylated Ketones via Cobalt-Catalyzed Acceptorless Dehydrogenation Coupling

In this paper, we report a non-noble metal catalyst as an efficient dehydrogenative catalyst for the synthesis of α-alkylated ketones from primary and secondary alcohols. Notably, this approach liberates H2 and H2O as the only byproducts, featuring environmental friendliness and atom economy. Extensive substrate scope, superior compatibility of functional groups, and good reactivity are demonstrated. Mechanistic studies reveal that the dehydrogenation of primary alcohols, rather than secondary alcohols, provides the major hydrogen source for the borrowing hydrogen pathway. The crucial proton transfer and hydride transfer steps are illustrated for the acceptorless dehydrogenation pathway.