Cobalt-catalyzed Selective Hydrogenation Of Cyclic Imide Derivatives

a-hydroxylactam compounds represent an important kind of organic molecules.They are important structural motifs and versatile building blocks in natural products and pharmaceuticals.Selective reduction of imide compounds is an effective route to obtain a-hydroxylactams.Under different conditions,reduction of imides can yield some types of products such as:a-hydroxylactam,benzamides,aliphatic cyclic amines,1,4-diols and isoindolinone derivtives etc.And there is less work to obtain?-hydroxylactam.Thus,selective reduction of imide to obtain ?-hydroxylactam is challenging.Presently,the methods of reducing this imide mainly are transition metal catalyzed hydrogenation or hydrosilation reduction.High atom utilization and simple post-processing are the advantages of using transition metal complexes to catalyze the hydrogenation of imide compounds.However,Taking into account the problem of residual metal and price factor,the development of hydrogenation of imide compounds based on the cheap metals catalysts is very urgent and has important practical significance.In this thesis,we used cheap metal cobalt complex(Co-PNN)as a catalyst to carry out selective hydrogenation reduction of phthalimide derivatives.The reaction can obtain a-hydroxylactam with excellent selectivities and yields.In additional,this catalytic system can selectively produce not only ?-hydroxylactam but also a ring-opening product with C-N bond broken.Firstly,a series of reaction conditions were investigated base on the changing of catalysts,the equivalent of the catalyst,the type of base,the pressure of hydrogen,the type of alcohol,the quantity of alcohol,etc.With the evaluation of reaction selectivities and yields,two optimal reaction conditions for obtaining a-hydroxylactam and ring-opening product were obtained,respectively.Next,the scope of substrates were investigated under the two reaction conditions and excellent yields and selectivities were obtained,respectively.The gram-level reaction can be carried out smoothly affording a-hydroxylactam compounds efficiently,which can be used for the synthesis of Nuevamine skeleton.