Transition Metal-catalyzed Asymmetric Hydrogenation Of Carbon-oxygen Double Bonds And Carbon-nitrogen Double Bonds

Chemical selective hydrogenation is one of the major challenges in the field of hydrogenation.The chemical selective hydrogenation of various unsaturated bonds is of great significance,which can greatly simplify the synthetic route and reduce the costs.In this paper,a cobalt catalyst system has been developed,which can achieve the chemical selective hydrogenation of polar double bonds.Chiral alcohols and chiral amine structures usually play an important role in drug molecules,bioactive molecules and functional materials.Among the methods for the synthesis of chiral alcohols and chiral amines,asymmetric hydrogenation has many advantages: high atom utilization,few side reactions and more in line with the concepts of green chemistry and sustainable development.In this paper,the efficient and highly stereoselective synthesis methods of chiral hydroxyphosphine and chiral aminophosphine fragments were developed.The contents of researches in this article are as follows:In this paper,a Co-P4N2 catalytic system has been developed,which was successful in the selective hydrogenation of unsaturated bonds.The catalytic system can selectively hydrogenate carbon-oxygen double bonds and carbon-nitrogen double bonds,but it will not hydrogenate conjugated or non-conjugated carbon-carbon double bonds.This is the first report that the cobalt catalyst system has this kind of chemical selectivity.It is worth mentioning that the catalyst is relatively stable,insensitive to water and oxygen,and can be prepared on a scale of 15 grams,which has good application prospects.In addition,the catalytic system achieved excellent results among wide range of substrates,with the turnover number up to 24,000.In this paper,the asymmetric hydrogenation of 2-(diphenylphosphoryl)-1-phenylethanone was achieved using the iridium complex of the O-Spiro PAP ligand previously developed by our group.Although the phosphorus-containing substrate has a strong coordination effect,the catalytic system can achieve highly efficient asymmetric hydrogenation of this type of substrate,indicating the stability of the Ir-O-Spiro PAP catalyst.After the optimization of the conditions,the highly efficient and high enantioselective hydrogenation of this type of substrate was successfully achieved.When using methanol as the solvent and potassium carbonate as the additive,99% conversion and 99% ee can be obtained.Based on the reductive amination strategy for ketones previously reported by our research group,asymmetric reductive amination of 2-(diphenylphosphoryl)-1-phenylethyl ketones was achieved,using Ru[(R)-DTBM-Segphos](OAc)2 as the catalyst and ammonium acetate as the ammonia source.For the first time,reductive amination strategy was used to synthesis of chiral fragments of aminophosphines.Compared to traditional methods,primary amines are constructed in one pot,with higher efficiency and atomic economy,which is in line with green chemical requirements.