One‐Pot Cobalt‐ or Copper‐Catalyzed Asymmetric Ring‐Opening Hydrosilylation/Hydroboration of Arylidenecyclopropanes

Abstract An operationally convenient cobalt‐catalyzed one‐pot one‐step hydrosilylation/hydroboration reaction of arylidenecyclopropanes is developed to access racemic 1,4‐borylsilylalkanes. In addition, the corresponding asymmetric reaction is developed with a chiral copper catalyst to prepare 1,4‐borylsilylalkanes with high enantioselectivity by a one‐pot two‐step procedure. Mechanistic studies reveal that this difunctionalization process begins with metal‐hydride‐catalyzed ring‐opening hydrosilylation of arylidenecyclopropanes to generate homoallylsilane intermediates, followed by regio‐ or enantioselective metal‐hydride‐catalyzed hydroboration of homoallylsilanes to produce skipped borylsilylalkanes. Selective transformations of C−B and Si−H bonds in skipped borylsilylalkane products are also demonstrated.