Chemoselective transfer hydrogenation of α,β-unsaturated carbonyl compounds using potassium formate over amine-grafted Ru/AlO(OH) catalysts

摘要: Grafting of 3-(2-aminoethylamino)propyltrimethoxysilane onto Ru/AlO(OH) resulted in an active and highly chemoselective heterogeneous catalyst for the transfer hydrogenation α,β-unsaturated carbonyl compounds to corresponding allylic alcohols. Potassium formate was used as a sustainable hydrogen donor. A range substrates including cinnamaldehyde, α-amylcinnamaldehyde, citral, 3-methyl-2-butenal, trans-2-pentenal, trans-hexenal were selectively hydrogenated at CO moiety with >96% selectivity. In comparison, unmodified 1 wt% catalyzed cinnamaldehyde CC bond, yielding 3-phenylpropanal product. Higher loaded samples 2–10 Ru exhibited 20–25% selectivity cinnamyl alcohol. The results show that low coordination sites more selective internal than terminal bond. Immobilization amine via chemical bonding hydroxyl groups AlO(OH) support blocks adjacent exposed metal sites, increasing reduction CO. Optimum achieved amine/Ru ratio 6. maintained high activity chemoselectivity even after five cycles.