Hydrochloric Acid → (3S)-1H,2H,3H,4H,9H-pyrido(3,4-b)indole-3-carboxylic acid

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Reaction Conditions

Reaction Steps

Formaldehyde (37% aq. solution, 39.7 mL, 490 mmol) was added to a stirred solution of L-tryptophan (100.0 g, 490 mmol) in aqueous sodium hydroxide solution (19.6 g in 200 mL of H2O, 490 mmol) and stirred for 2 hr. The mixture was heated to reflux and stirred for 3.5 hr. The mixture was cooled to 50° C. and carefully acidified to pH 5-6 with 6.0 M HCl(aq) solution. The mixture was diluted with water (200 mL). The flask was removed from heat and cooled to room temperature. The precipitates filtered off and washed with water. The solids were resuspended in THF (800 mL), stirred at RT for 1 hr, and filtered to afford compound 1 (101.3 g, 95%) as beige solid. 1H NMR (300 MHz, DMSO-d6): δ 10.93 (s, 1H), 8.88 (br s, 1H), 7.43 (d, 1H), 7.31 (d, 1H), 7.02 (t, 1H), 6.97 (t, 1H), 4.18 (q, 2H), 3.61-3.56 (m, 1H), 3.12 (dd, 1H), 2.83-2.75 (m, 1H); LC-MS [M+H+ 217].

Provenance & Evidence