Ligand-Controlled Cu-Catalyzed Regio-Divergent and Enantio-Selective Hydroboration and Boroamination of Tri-Substituted Cyclopropene

Development of efficient protocols for the synthesis of stereo-defined multi-substituted cyclopropanes remains a daunting challenge. Herein, we report the ligand-controlled Cu(I)-catalyzed highly regio-divergent and enantio-selective hydroboration and bora-amination of tri-substituted cyclopropenes for the access to stereo-defined tetra - and penta -substituted cyclopropyl boronic esters. By judicious choice of commercially available chiral phosphine ligands, either 1,1- or 1,2-borylsilylated cyclopropanes can be accessed in high enantio-control. The products can serve as valuable cyclopropane-containing synthons. Mechanistic experiments and DFT calculations revealed the origins for the high enantio- and regio-chemical control.