Water As A Proton Mediator For Dioxygen-Selective Oxidation Of Alcohols/Amines Catalyzed By Cu₂?ophen?₂

In recent years,seeking a cheap,efficient,green organic synthesis methods have been widespreadly concerned under the advocacy of the green chemistry and the concept of sustainable development,and study on the transition metal in the catalytic application has become a hot topic.Compared with noble metals,copper is abundant in nature,cheap and easy to obtain,low toxicity,so that copper has been widely studied in the field of catalysis.In this paper,we selected Cu₂?ophen?₂ as catalyst and green O₂ as oxidant to achieve selective oxidation of alcohols and amines.It is divided into four parts,which are summarized as follows:In the first chapter,the copper catalysis,oxidation reaction and the activation of Cux- O₂ mode were briefly introduced,and the significance of the research topic and the research progress were described.In the second chapter,the background of alcohols oxidation and the selective oxidation of alcohols catalyzed by Cu₂?ophen?₂/ O₂ were reported.Without any bases and expensive nitroxyl derivatives,the Cu₂?ophen?₂ can be used as a catalyst for the selective oxidation of alcohols to aldehydes and ketones under the dioxygen atmosphere.The experimental part has been further improved and the effect of various factors on the reaction conversion is verified in detail.Combining with the DFT calculations and ESI-MS experiments,a novel oxidation mechanism of "water as proton mediator" is proposed,which involves O₂?Cu-OO /Cu-OO-Cu?and H2 O₂ two different oxidation process.A series of shape changes of the Cu-complex,from “stretched to folded to stretched” occurred during two catalyzed cycles.At the same time,the valence of the metal center and the strength of the Cu-Cu weak bond were also changing regularly.The defined structure of the dinuclear complex is better than that of systems composed of copper salt/ligands,providing a good platform for mechanisticinvestigation.The third chapter mainly reports on the background of the oxidation of amines and the selective oxidation of amines catalyzed by Cu₂?ophen?₂/ O₂.We achieved the selective oxidation of amines in the mild reaction conditions by Cu₂?ophen?₂ as the catalyst,green O₂/air as the oxidant with avoiding the use of bases and expensive nitroxyl derivatives,the conversion and selectivity are very high.Using the same catalyst Cu₂?ophen?₂,a series of imine compounds were successfully synthesis by cross-coupling of alcohols and amines,dehydrogenative homocoupling of primary amines and oxidative dehydrogenation of secondary amines,which is very difficult to achieve in the existing reports.The fourth chapter is the summary of this paper,and the prospect of the research prospects.