A dancing nickel in asymmetric catalysis: Enantioselective synthesis of boronic esters by 1,1-addition to terminal alkenes

Chiral benzylic boronic esters were synthesized through a simple three-component reaction involving a terminal alkene, an aryl bromide and B2pin2 using a nickel catalyst. Interestingly, the reaction yielded a 1,1-difunctionalized alkane instead of a 1,2-difunctionalized product. Mechanistic investigations supported a 1,2-Ni migration to achieve the 1,1-difunctionalized product. The 1,1-addition addition products were obtained in good yields and high chemo and regio-selectivity without the need for directing groups. When a chiral Ni catalyst was employed, the resulting boronic esters were prepared with excellent enantioselectivity.