Flavin‐Functionalized Gold Nanoparticles as an Efficient Catalyst for Aerobic Organic Transformations

Monolayer‐protected gold clusters functionalized with synthetic flavins were synthesized and their catalytic activity in aerobic organic transformations investigated. Gold nanoparticles with 5‐ethyl‐3‐(8‐thiooctyl)lumiflavinium perchlorate acts as an efficient catalyst for the aerobic oxidation of organic sulfides to the corresponding sulfoxides upon treatment with hydrazine at room temperature and under atmospheric pressure in oxygen. With a catalytic amount of gold nanoparticles with 3‐(8‐thiooctyl)lumiflavin, diimide reduction of various olefins can be performed with hydrazine at room temperature under atmospheric pressure in air with greater yields of product alkanes than with non‐supported 3‐methyllumiflavin catalyst under the same conditions. Kinetic studies revealed that the monolayer‐protected gold cluster‐catalyzed reactions proceeded faster than those with non‐supported catalysts over the full substrate concentration range for the hydrogenation of olefins and at lower substrate concentrations for sulfoxidation. This positive effect was rationalized by assuming a Michaelis–Menten‐type mechanism in which the specific inclusion of substrates into the enzyme‐like reaction cavities was a key factor in the high efficiency of the supported flavin catalysts.