| Catalytic hydrogenation reaction is one of the most important transformations in organic synthesis and industrial production,early studies were mainly based on noble metal-catalyzed hydrogenation of unsaturated bonds.Compared with hydrogen gas,hydrosilane and hydroborane are safer,more inexpensive and milder source of hydrogen.Transition metal catalyzed hydrosilylation and hydroborolation represent simple and efficient methods of reductive hydrogenation.With the development of science and the increasing shortage of resources,the development of abundant,inexpensive and environmentally friendly metal catalysts has gained much attention from scientists in recent years.Manganese,as the third most abundant transition metals in the earth’s crust,is rich in oxidation valence state and is expected to replace precious metals as new efficient catalysts.Therefore,the development of manganese catalyzed hydrogenation reaction is of great importance.In this paper,we focus on two parts of manganese-catalyzed hydrosilylation of amides in the presence of hydrosilane as well as hydroborolation of alkynes using hydroborane as hydrogen sources.Part one:Amines are a very important class of compounds,the reduction of amides is the most direct method for the synthesis of amines.Compare with the conventional metal hydride,transition metal-catalyzed hydrosilylation is simpler and more efficient.In this section,we achieved the deoxygenation of secondary and tertiary amides enabled by[Mn（CO）5Br]using Ph2Si H2 or polymethylhydrosiloxane（PMHS）as the hydrogen source in the absence of external ligand.The reaction substrate is wide,the functional groups are well tolerated and the corresponding amine compounds can be obtained in high yields in the most cases.In addition,the catalytic system is also suitable for some bioactive molecules containing an amide backbone.Through simple mechanistic experiments,we found that the reduction of secondary amides is through the imine intermediate pathway to obtain the target products,and hydrogen gas is produced during the reaction.Part two:Alkenyl boronates are a very important class of synthetic blocks in organic synthesis,which are widely used in C–C coupling.Traditionally,the borylation of alkenyl metallic reagents and borane required to synthesize alkenyl boronate compounds,but this method produces stoichiometric metal salts.Transition metal-catalyzed hydroborolation reactions of alkynes are a simple and efficient synthesis method.Here,we investigated the selective hydroborolation formation ofα-alkenyl boronates by pincer manganese complexes using HBpin as the hydrogen source. |
