Phenanthrenequinone-Sensitized Photocatalytic Synthesis of Polysubstituted Quinolines from 2-Vinylarylimines
Juulia Talvitie, Iida Alanko, Evgeny Bulatov, Juho Koivula, Topias Pöllänen and Juho Helaja*
*Department of Chemistry, University of Helsinki, A. I. Virtasen aukio 1, 00014 Helsinki, Finland, Email: juho.helajahelsinki.fi
J. Talvitie, I. Alanko, E. Bulatov, J. Koivula, T. Pöllänen, J. Helaja, Org. Lett., 2022, 24, 274-278.
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Visible-light-excited 9,10-phenanthrenequinone (PQ*) catalyzes a mild and efficient electrocyclization of 2-vinylarylimines for the synthesis of 2,4-disubstituted quinolines in very good yields.
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Imine (1 equiv), PQ (15 mol%), MgCO3 n-hydrate (20 mg/mL, 2.1 equiv) and DCM (1 or 2 mL, so that the concentration of imine was 0.1 M) were added in a 20 mL vial, which was sealed with a septum. The atmosphere in the vial was exchanged with dry air (balloon) for 15 min. The balloon was left attached and the reaction mixture was stirred and irradiated with blue LEDs (455 nm) at r.t. for the time needed. The reaction mixture was filtered through Celite and washed with DCM. The solvent was evaporated from the filtrate on rotary evaporator and the crude was purified with flash chromatography on silica gel.
quinolines, photochemistry, organocatalysis