Accessing Highly Substituted Indoles via B(C₆F₅)₃-Catalyzed Secondary Alkyl Group Transfer

Herein, we report a synthetic method to access a range of highly substituted indoles via the B(C₆F₅)₃-catalyzed transfer of 2° alkyl groups from amines. The transition-metal-free catalytic approach has been demonstrated across a broad range of indoles and amine 2° alkyl donors, including various substituents on both reacting components, to access useful C(3)-alkylated indole products. The alkyl transfer process can be performed using Schlenk line techniques in combination with commercially available B(C₆F₅)₃·<i>n</i>H₂O and solvents, which obviates the requirement for specialized equipment (e.g., glovebox).