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·nH2O and solvents, which obviates the requirement for specialized equipment (e.g., glovebox).