Single‐Site Molybdenum Catalyst for the Synthesis of Fumarate

The catalysts with well‐defined mononuclear active sites are expected to develop more active catalytic systems for the key chemical transformations. But the rational design of catalyst with stable mononuclear Mo site is still a crucial challenge because of its oligomerization tendency under reaction condition. Herein, Molybdenum catalyst (Mo‐8‐HQ) with single Mo sites was designed via the pyridine nitrogen and oxygen in hydroxyl of 8‐hydroxyquinoline coordinated with Mo atom. The crystal catalyst was stabilized by π‐π stacking interaction and hydrogen bonds to form isolated Mo specie. The single‐site molybdenum catalyst exhibited excellent catalytic performance in didehydroxylation reactions with high selectively of dibutyl fumarate (86 %) product at mild reaction condition. Deuterium isotopic studies demonstrated that the mechanism feature of didehydroxylation reaction catalyzed by Mo‐8‐HQ was through concerted cleavage of two C−O bonds process, which could be accelerated by single‐site molybdenum catalysts with electron‐rich Mo centers.