Direct Synthesis of Hydroquinones from Quinones through Sequential and Continuous-Flow Hydrogenation-Derivatization Using Heterogeneous Au-Pt Nanoparticles as Catalysts.

Pt-Au bimetallic nanoparticle catalysts immobilized on dimethyl polysilane (Pt-Au/(DMPSi-Al2 O3 )) have been developed for selective hydrogenation of quinones to hydroquinones. High reactivity, selectivity, and robustness of the catalysts were confirmed under continuous-flow conditions. Various direct derivatizations of quinones, such as methylation, acetylation, trifluoromethanesulfonylation, methacrylation, and benzoylation were successfully performed under sequential and continuous-flow conditions to afford the desired products in good to excellent yields. Especially, air-sensitive hydroquinones, such as anthrahydroquinones and naphthohydroquinones, could be successfully generated and derivatized under closed sequential and continuous-flow conditions without decomposition.