Sodium Hydroxide → 5,6-Dihydro-4H-pyrrolo[3,2,1-ij]quinoline-1-carboxylic acid

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Reaction Steps

To a solution of 5,6-dihydro-4H-pyrrolo[3,2,1-ij]quinoline-1-carboxylic acid ethyl ester (31 g, 0.14 mol) in ethanol (200 ml) and water (200 ml) was added sodium hydroxide (30.8 g, 0.77 mol). The mixture was heated to reflux for 2 hours before being cooled to room temperature and diluted with water (2.64 L). The mixture was then washed with dichloromethane (2×300 ml) and the aqueous layer was acidified with concentrated hydrochloric acid to pH 1.0. The precipitate formed was collected by filtration, washed with water and dried to yield 5,6-dihydro-4H-pyrrolo[3,2,1-ij]quinoline-1-carboxylic acid as a dark yellow solid (23 g, 85%). 1H NMR (DMSO-d6) 400 MHz δ: 11.95(brs, 1H), 7.96(s, 1H), 7.69(d, 1H, J=8.4 Hz), 7.06(t, 1H, J=6.8 Hz), 6.92(d, 1H, J=6.8 Hz), 4.19(t, 2H, J=6 Hz), 2.91(t, 2H, J=6 Hz), 2.11(t, 2H, J=5.6 Hz).

Provenance & Evidence