Selective N-alkylation of indoles with primary alcohols using a Pt/HBEA catalyst

Abstract

Pt-loaded HBEA (H⁺-exchanged BEA zeolite) is found to be an effective and reusable heterogeneous catalyst for regioselective N-alkylation of indoles with primary aliphatic and benzylic alcohols under additive-free conditions driven by the borrowing-hydrogen methodology. Structural and mechanistic studies suggest a cooperative mechanism of the Pt⁰ site on Pt metal clusters and the Brønsted acid site of the zeolite, in which the Pt⁰ site is responsible for dehydrogenation/hydrogenation steps and the Brønsted acid site is responsible for the regioselective condensation of indoles with aldehydes to the enamine intermediate.