Studies On The Reduction And Recycling Of Phophine Oxides And The Reduction Of Nitro Compounds

As an important class of organophosphorus compounds,tertiary phosphines have been widely used as ligands,organocatalysts and reagents in organic synthesis.However,in such phosphine-meditated reactions like Mitsunobu reaction and Wittig reaction,phosphine oxides were produced as by-product,which lead to the poor atom economy and the waste of phosphorus resource.The shortage of phosphorus resource is one of the serious resource crisis in the world.The reduction and recycling of phosphine oxides,and the development of phosphine-catalyzed reaction,is of great significance.Amines are a class of important organic compounds,which exist as the core structural units of many natural products and drug molecules.There were many methods for the synthesis of amines.The reduction of nitro compounds to amines is one of the most direct methods for the synthesis of aromatic amines.The introduction of nitro groups on aromatic rings is relatively convenient,and with good functional group tolerance.And this transformation has been widely used in industrially drug molecules synthesis.This dissertation mainly includes two aspects:1.Iridium catalyzed reduction and recycling of phosphine oxidesBased on our previous work,we have expanded the scope of substrates in iridium catalyzed reduction of phosphine oxide compounds and studied the effects of additives in the iridium catalytic system.Based on this,the tandem of reduction of phosphine oxides and phosphine-participated reactions,such as Mitsunobu reaction and Wittig reaction,was developed.2.Iridium catalyzed hydrogenation of nitro compoundsUsing[Ir-HF-Y]as catalyst,TEA as additive,and hydrogen as reducing agent,a gentle and efficient method for reduction of nitro compounds has been developed.The reaction was carried out at room temperature under atmosphere pressure,which shows good substrate practicability and chemoselectivity.With 0.1 mol%of Ir catalyst,the gram-scale preparation of aniline was achieved by the hydrogenation of nitrobenzene.