Asymmetric Ag/Cu-catalyzed 1,3-dipolar Addition Reaction

Catalytic asymmetric 1,3-dipolar additions have turned out to be one of the most efficient methods for the preparation of chiral glutamic acid derivatives and enantioenriched pyrrolidines.In recent years,a bunch of catalytic systems have been well-established,however,the development of 1,3-dipolar additions with novel framework compounds for preparation of structurally complex enantiomerically enriched compounds are still a challenging topic.Herein,a variety of chiral glutamic acid derivatives and enantioenriched substituted pyrrolidines were synthesized in the following research:1.The enantioselective construction of a family of chiral glycine-derived aldimino esters is described.The asymmetric tandem conjugate additionelimination procedure is characterized by its exceptional mild reaction conditions and features with an exquisite enantioselectivity profile using silver/DTBM-SegPhos catalyst,allowing for the facile preparation of a variety of substituted and chiral glutamic acid derivatives(92-99% ee)bearing Schiff base in a straightforward manner.2.Herein,we find that the silicon-based bulky group enables a 1,3-dipolar addition-initiated parallel kinetic resolution(PKR)to occur unexpectedly,leading to the highly enantioselective synthesis of two structurally different types of amino acid derivatives via [3+2] cycloaddition reactions and tandem conjugate addition-elimination reaction respectively.The resulting and structurally divergent enantioenriched amino acid derivatives that contain four contiguous stereogenic centers and an all-carbon quaternary center were obtained with up to 99% ee with >99:1 dr and good yields.In conclusion,a variety of chiral glutamic acid derivatives and multisubstituted chiral pyrrolidine derivatives have been successfully synthesized via Ag(I)/(R)-DTBM-SegPhos or Cu(I)/(R)-DTBM-SegPhos-catalyzed enantioselective 1,3-dipolar addition.