1,1-Diborylalkanes as Versatile Precursors for Copper-Catalyzed Diastereo- and Enantioselective Allylic Substitution

Abstract While copper-catalyzed asymmetric allylic alkylation has undergone substantial advances, achieving high levels of stereocontrol with hard nucleophiles remains a formidable challenge. We have recently reported an efficient copper-catalyzed regio-, diastereo-, and enantioselective allylic alkylation of allyl bromides using 1,1-diborylalkanes as prochiral hard nucleophiles. This methodology employs CuBr as a catalyst, an (R)-BINOL-derived phosphoramidite as a chiral ligand, and lithium benzoate as a crucial additive, providing enantioenriched homoallylic boronic esters in good yields with excellent stereoselectivity. Our mechanistic investigations revealed that lithium benzoate is the key to facilitating highly selective anti-SN2′-type oxidative addition, offering valuable insights for further development of asymmetric copper catalysis. 1 Introduction 2 Copper-Catalyzed Regio-, Diastereo-, and Enantioselective Allylic Alkylation with 1,1-Diborylalkanes 3 Conclusions and Perspectives