Selective C‐alkylation Between Alcohols Catalyzed by N‐Heterocyclic Carbene Molybdenum.

The first implementation of a molybdenum complex with an easily accessible bis‐N‐heterocyclic carbene ligand to catalyze β‐alkylation of secondary alcohols via borrowing‐hydrogen (BH) strategy using alcohols as alkylating agents is reported. Remarkably high activity, excellent selectivity, and broad substrate scope compatibility with advantages of catalyst usage low to 0.5 mol%, a catalytic amount of NaOH as the base, and H2O as the by‐product are demonstrated in this green and step‐economical protocol. Mechanistic studies indicate a plausible outer‐sphere mechanism in which the alcohol dehydrogenation is the rate‐determining step. [ABSTRACT FROM AUTHOR]