Study On Aerobic Oxidative Reaction Catalyzed By DDQ/TBN Under Atmospheric Pressure

2,3-Dichloro-5,6-dicyano-1,4-benzoquinone(DDQ)plays a crucial role in organic synthesis as a powerful organic oxidant.It has been extensively utilized in different areas,such as alcohol oxidation,aromatization,oxidative coupling,protecting group removal and benzylic acetoxylation,and many other reactions.Our research group has developed DDQ/tert-butyl nitrite(TBN)catalyst system for the aerobic oxidation of alcohols and oxidative deprotection of p-methoxybenzyl(PMB)ethers in autoclave.For the purpose of simplifying the equipment and extending the substrate scope,we investigated the benzylic alcohol oxidation and the oxidative deprotection of several benzyl-type ethers at atmospheric pressure of O2 in the presence of DDQ/TBN.At first,the DDQ/TBN catalytic system was applied in the oxidation of benzylic alcohols under atmospheric pressure of 02.The oxidation of benzyl alcohol to benzaldehyde was investigated as the model reaction to optimize the reaction conditions.Under the optimized reaction conditions,the oxidations of benzylic alcohols into aldehydes were performed.It was found that satisfactory results could be obtained when benzylic alcohols with electron-donating substituent group on the benzene ring were used as the substrates.Secondly,the DDQ/TBN catalytic system was applied in the oxidative deprotection of PMB and p-phenylbenzyl(PPB)ethers under atmospheric pressure of O2.The reaction conditions were optimized in the model oxidation deprotection reaction of PMB ether of ?-phenylethanol.Under the optimized conditions(chlorobenzene as the reaction solvent,5 mol%DDQ,5 mol%TBN,100 ?),a variety of PMB and PPB ethers could be quantitatively converted with high selectivities to products(>95%).Selective deprotection of hydroxyl groups was also investigated,and desired results could be obtained.