A One-Pot Route to Indole-3-acetaldehydes, Tryptophols, and Tryptamine-Based Alkaloids from Indoles

An efficient and operationally simple Brønsted acid catalysis provides a direct scalable route to indole-3-acetaldehydes starting from readily available indole derivatives. A number of tryptophols and tryptamines were accessed from these valuable precursors through simple functional group interconversions. Further showcasing the utility of this strategy, syntheses of tryptamine-based marine alkaloids deformylflustrabromine and brocaeloid C, and a selective h5-HT_2A receptor antagonist, were accomplished in one-pot operation. To note, the latter antagonist was obtained in gram-scale, demonstrating the scalability of this one-pot sequential protocol.