Construction And Study Of DDQ/FePc/O₂ System For Catalytic Oxidation Reactions

2,3-Dichloro-5,6-dicyano-1,4-benzoquinone（DDQ）is an excellent oxidant,which can be used in many reactions such as oxidative deprotection,alcohols oxidation,aromatization,and so on.Phthalocyanines（Pcs）are planar macrocycles constituted by four isoindole units possessing 18Ï€-electron.Iron（II）phthalocyanine（FePc）can be obtained after the two hydrogen atoms of phthalocyanine are replaced by a ferrous ion.FePc showed good catalytic activity in the aerobic oxidation of hydroquinone into benzoquinone.Based on these informations,our research group constructed DDQ/FePc/O₂ system,a new catalytic oxidation system,and applied it to different oxidation reactions.Firstly,the DDQ/FePc/O₂ system was applied in the oxidative deprotection of PMB ether in autoalave.PMB ether of 2-octanol was selected as the model substrate to optimize the reaction conditions.Under the optimized conditions（toluene as the reaction solvent,10 mol%DDQ,10 mol%FePc,10 mol%4,4’-Bpy,0.4 MPa of oxygen pressure,80℃）,most of the substrates could be converted to corresponding alcohols in high selectivities.The substrates with two different hydroxyl protecting groups were also submitted to the oxidative deprotection reactions.The results showed that using this procedure the PMB ethers were selectively cleaved,giving the corresponding alcohols without affecting the other functional groups.Subsequently,the DDQ/FePc/O₂ system was applied to other reactions,such as aromatization,alcohol oxidation andα,β-unsaturated aldehyde formation.Cinnamyl alcohol,indoline and 3-propionaldehyde were selected as typical substrates for the studies,and desired results could be obtained.