8-Hydroxy-5,6,7,8-tetrahydroquinoline → 6,7-Dihydro-5H-quinoline-8-one

Participants

Reaction Steps

To a stirred solution of 8-hydroxy-5,6,7,8-tetrahydroquinoline (13.96 g, 93.6 mmol) in dry CH2Cl2 (400 mL) was added activated manganese dioxide (85% purity, 82.22 g, 804 mmol). The resulting heterogeneous mixture was stirred 18 h, at which point the black slurry was filtered through a cake of celite and washed with CH2Cl2 (3×50 mL). The combined washings were concentrated to afford 11.27 g (82%) of the title compound as a pale yellow solid, which was used in subsequent reactions without further purification. 1H NMR (CDCl3) δ 2.17–2.25 (m, 2H), 2.82 (t, 2H, J=7 Hz), 3.04 (t, 2H, J=6 Hz), 7.37 (dd, 1H, J=9, 6 Hz), 7.66 (dd, 1H, J=9, 1 Hz), 8.71 (dd, 1H, J=6, 1 Hz); 13C NMR (CDCl3) δ 22.2, 28.6, 39.2, 126.6, 137.3, 140.5, 147.6, 148.6, 196.5. ES-MS m/z 148 (M+H).

Provenance & Evidence