Application Of Tert-Butylsulfinamide Phosphine Ligand In Asymmetric Carboamination

The combination of transition metals and chiral ligands to catalyze asymmetric reactions has become an important method for constructing chiral compounds.Among them,the chiral ligand can be distinguished between a pair of enantiomeric products,the superior product is selected,and a single configuration product with an excess of enantiomers can be obtained.Therefore,the development of new ligands and asymmetric reactions is the core content of the field of asymmetric catalysis.This paper focuses on the design,modification of the new tert-butylsulfinamide phosphorus ligand and its application in palladium-catalyzed asymmetric carboamination to obtain chiral isoxazolidines and pyrrolidines.Through the modification of the reported tert-butylsulfinamide phosphorous ligand Xu-Phos,a new Xu-Phos with ortho-position side arms was synthesized(these side arms include ortho-O~iPr,ortho-OBn,ortho-(naphthalen-2-ylmethoxy).The addition of these groups makes the new ligand more electron-density than the previous Xu-Phos,and increases the steric hindrance of the ligand,making it more competitive in asymmetric transition metal catalytic reactions.The addition of these groups makes the new ligands more electron dense than the previous Xu-Phos,and increases the steric hindrance of ligands,which makes them more competitive in transition metal asymmetric catalytic reactions.Efficient palladium catalyzed enantioselective carbamination of N-Boc-O-homoallyl-hydroxylamine and N-Boc-penta-4-allylamine with aryl or alkenyl bromides was developed to provide a variety of substituted isoxazolidines and pyrrolidines in high yields and up to97%ee.The reaction is featured by mild conditions,general substrate range and scalability.The obtained products can be converted into chiral 1,3-aminoalcohol derivatives without destroying the chirality.The newly identified Xu-Phos ligand bearing an ortho-O~iPr group is responsible for the good yields and high enantioselectivity.