Water → 9-(2,5-Dichlorobenzyl)-9H-beta-carboline-3-carboxylic acid

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Reaction Steps

9-(2,5-Dichlorobenzyl)-9H-β-carboline-3-carboxylic acid was prepared as described for the corresponding 9-unsubstituted compound (Hagen et al., Heterocycles 1986, 24:2845). A mixture of methyl 9-(2,5-dichlorobenzyl)-9H-β-carboline-3-carboxylate (15.0 g, 0.0389 mol), sodium hydroxide (2.0 g, 0.05 mol), water (75 mL), and 95% ethanol (200 mL) was refluxed for 1 hour. The mixture was concentrated in vacuo, and the residue dissolved in warm water (500 mL), and the pH adjusted to 3 using dilute HCl with vigorous stirring, resulting in the precipitation of a solid. The fine slurry was filtered, washed thoroughly with water, and dried in vacuo overnight at 70° C., and for another day at 85° C., affording 12.60 g (87%) of product. In another run, the product was isolated in 82% yield after recrystallization from hot acetic acid. The product had the following properties: 1H NMR (300 MHz, DMSO-d6) δ9.16 (s, 1H), 9.08 (s, 1H), 8.59 (d, J=8.0, 1H), 7.60-7.69 (m, 3H), 7.39-7.44 (m, 2H), 6.705 (d, J=2.3, 1H), 5.93 (s, 2H), 1.93 (s, 3H); LRMS calcd for C19H10Cl2N2O2 (M+H) 371, found 371.0.

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