Shedding light on Brønsted acid catalysis--a photocyclization-reduction reaction for the asymmetric synthesis of tetrahydroquinolines from aminochalcones in batch and flow.

A new asymmetric photocyclization-reduction cascade employing readily available aminochalcones has been developed. The reaction sequence has been achieved by unifying photochemistry and asymmetric Brønsted acid catalysis and involves photocyclization followed by Brønsted acid catalyzed enantioselective hydrogenation in batch and flow.