KO<i>t</i>Bu-Catalyzed 1,2-Silaboration of N‑Heteroarenes to Access 2‑Silylheterocycles: A Cooperative Model for the Regioselectivity

Reductive functionalization of N-heteroarenes offers a route to highly versatile heterocyclic synthons bearing multiple transformable groups. We present herein the development of KOtBu-catalyzed 1,2-silaboration of a broad range of N-heteroarenes, affording heterocyclic allylamines or enamines with the formation of a sp3 C2–Si bond. These labile compounds were isolated either as their N-acyl derivatives or as rearomatized 2-silyl-N-heteroarenes by the one-pot procedures. A model of the six-membered ion-pair complex was proposed to rationalize the observed 1,2-regioselectivity, wherein KOtBu catalyst plays an associative role in activating the substrate and silylborane reagent.