The Synthesis Of Supported Chiral Monodentate Phosphorus And Their Catalystic Performance In Asymmetric Reactions

One of the key isues of asymmetric catalysis is the synthesis of chiral ligands.In this paper,a new type of chiral monodentate phosphorus ligand with unsaturated bond were designed and synthesized.The structures of the chiral monodentate phosphorus ligands were characterized and their catalytic performance in asymmetric hydrogenation and hydrosilylation reactions were studied.These ligands were further loaded on the surface of mesoporous materials.The recycling behavior of the supported catalyst were also investigated.The details are as follows:?1?A chiral monodentate phosphorus ligand with terminal alkynyl group was synthesized by using propargyl bromide,p-hydroxybenzaldehyde and S-BINOL as raw materials.The ligand was applied in the Rhodium-Catalyzed asymmetric hydrogenation of?-dehydrogenated amino acid methyl ester and up to 90%ee was obtained,The alky bond was maintained in the entire catalytic process.?2?The 3,3'-positions of BINOL was substituted by different steric/electronic groups?methyl,phenyl,2-naphthyl,4-methoxyphenyl?by Suzuki reaction.These 3,3'-modified BINOLs were reacted with phosphorus trichloride and secondary amines to yield of vinyl-terminated chiral monodentate phosphoramide ligands.The structure was characterized by¹H-NMR,¹³C-NMR,³¹P-NMR,HRMS?ESI?etc.The ligands were used in the Iridium-catalyzed asymmetric hydrogenation of?-dehydrogenated amino acid esters.The chiral monodentate phosphorus ligand phenyl-substitued in the 3,3'-positions of chiral skeleton was the best ligand and up to 99.6%ee was obtained.?3?The vinyl-modified chiral monodentate phosphorus ligands were used in the Pd-catalyzed asymmetric hydrosilylation reaction of styrene.The ligandwith4-methoxyphenyl substituted in the 3,3'-positions of chiral skeleton was the best ligand,and up to 91%ee was obtained.Through"click chemistry"reaction,the 3,3'-phenyl substituted ligand was supported on the mesoporous material.The supported catalyst was applied in the Pd-catalyzed asymmetric hydrosilylation of styrene,up to 85%ee was obtained.The loaded catalyst could be recycled 3 runs,the selectivity was also maintained.