Design,Synthesis Of Hexamethyl-1,1'-Spirobiindane-based Phosphine-Oxazoline Ligands And Their Applications In Ni-Catalyzed Asymme-Tric Arylation Of Cyclic Aldimines

P,N ligands occupy a significant position among chiral ligands.These ligands have been widely used in asymmetric catalysis due to its characteristics of both phosphine ligands and nitrogen ligands which have made them exhibit excellent catalytic activity and enantioselectivity in reactions.The phosphine-oxazoline ligand is one of the more classic category among P,N ligands.In this dissertation,firstly we reviewed the development progress of chiral phosphine-oxazoline ligands,and then reported the synthesis of novel hexamethyl-1,1'-spirobiindane-based phosphine-oxazoline ligands(HMSI-PHOX),and their application in nickel-catalyzed asymmetric arylation reaction of N-sulfonyl imines and arylboronic acids.The details are summarized as following:1.The racemic hexamethyl sprio dibromide as a key intermediate was prepared in four steps from bisphenol C via cyclization,bromination,esterification,and reduction,with an overall yield of 73.8%.Then on basis of above mentioned,a pair of diastereomers as the desired targeted ligands were synthesized and seperated in a six-steps reaction procedure,including coupling,reduction,cyanidation,hydrolysis,condensation,and cyclization,followed by separation by flash chromatography.Finally,eight kinds of pure chiral phosphine-oxazoline ligands with a novel hexamethyl spirobiindane scaffold were obtained in a total yield of 26.2%-30.9%,and the absolute configuration of a ligand was determined by X-ray crystallographic analysis of a single crystal.2.A highly enatioselective arylation of N-sulfonyl imines with arylboronic acids catalyzed by Ni/HMSI-PHOX was developed.Using benzo[e][1,2,3]oxathiazine-2,2-dioxide derivatives and arylboronic acids as starting materials,the ligands,metal precursors,and solvents were screened,seventeen optically active 4-ary 1-3,4-dihydrobenzo[e][1,2,3]oxathiazine-2,2-dioxide derivatives were obtained in high yields(up to 94%)with excellent enantioselectivities(up to 99%)under the optimal reaction conditions of 5 mol%Ni(ClO4)2·6H2O and 7.5 mol%(Ra,S,S)-2.11d in trifluoroethanol at 60 ? for 48 hours.