Palladium-catalyzed C3-alkylation of indoles with alcohols via hydrogen borrowing cascade

Indole represents a privileged scaffold extensively used in drug design due to its promise to improve both binding affinity and specificity receptors. Direct functionalization of indole framework is an efficient route to achieve structurally diverse indole derivatives. Herein, highly regio-selective C3-alkylation of indoles via hydrogen borrowing methodology (HBM) has been established using alcohols as the alkylation reagents by palladium catalysis. This method enables an efficient synthesis of C3-alkylated indoles, demonstrating high group adaptability to both indole and alcohol substrates (20 examples, up to 94% yield).