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To a stirred solution of methyl L-METHYL-LH-INDOLE-5-CARBOXYLATE (500 mg, 2.65 mmol) in MEOH (5 mL) is added sodium hydroxide (20 mL of a 2.5% aqueous solution). The mixture is heated at 80C for 1.5 h and MEOH is removed in vacuo. The remaining aqueous solution is acidified with 1 N aqueous HC1 to pH = 2. The resulting precipitate is collected by filtration, washed with water and dried in vacuo to afford 1-METHYL-LH-INDOLE-5-CARBOXYLIC acid as a white solid (437 mg, 94%) : LH NMR (400 MHz, DMSO-d6) 8 12. 44,8. 23,7. 75,7. 50,7. 44,6. 57,3. 83. |
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In sodium hydroxide; ethanol; |
Step B. 1-Methyl-indole-5-carboxylic Acid A solution of <strong>[128742-76-7]1-methyl-indole-5-carboxylic acid methyl ester</strong> of Step A (2.5 g, 13.2 mmol) in ethanol (40 mL) containing 2.5N aqueous NaOH (3:1, v/v) was heated at reflux for one hour. The reaction mixture was concentrated in vacuo, and the residue partitioned between diethyl ether and 1N HCl. The organic layer was washed with brine, dried over sodium sulfate, and evaporated to dryness to provide the title compound as an off-white solid (1.82 g). NMR (DMSO-d6, 300 MHz): delta 3.82 (s, 3H), 6.58 (dd, 1H), 7.42 (d, 1H), 7.48 (d, 1H), 7.75 (d, 1H), 8.22 (s, 1H), 12.38 (broad s, 1H). |
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In sodium hydroxide; ethanol; |
Step B. 1-Methyl-indole-5-carboxylic acid A solution of <strong>[128742-76-7]1-methyl-indole-5-carboxylic acid methyl ester</strong> of Step A (2.5 g, 13.2 mmol) in ethanol (40 mL) containing 2.5N aqueous NaOH (3:1, v/v) was heated at reflux for one hour. The reaction mixture was concentrated in vacuo, and the residue partitioned between diethyl ether and 1N HCl. The organic layer was washed with brine, dried over sodium sulfate, and evaporated to dryness to provide the title compound as a off-white solid (1.82 g). NMR (DMSO-d6, 300 MHz): delta 3.82 (s, 3H), 6.58 (dd, 1H), 7.42 (d, 1H), 7.48 (d, 1H), 7.75 (d, 1H), 8.22 (s, 1H), 12.38 (broad s, 1H) |
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To a solution of the crude product 1-37 in THF (80 mL) was added 80 mL of a 1 M LiOH aqueous solution. The mixture was stirred at 500C for 24 hours and then diluted with diethyl ether. After the mixture was then extracted twice with a saturated NaHCtheta3 aqueous solution, 6 M HCl was added to the combined aqueous layers to adjust the pH to 1. The aqueous layer was then extracted with ethyl acetate. The combined ethyl acetate layer was dried over Na2SO4, filtered, and concentrated to give compound 1-38 (4.72 g, 87%). 1H NMR (CDCl3) delta 8.49 (s, IH), 8.01-7.98 (dd, J = 8.4 Hz, 1.5 Hz, IH), 7.38-7.35 (d, J = 8.7 Hz, IH), 7.14-7.13 (d, J = 3.0 Hz, IH), 6.63 (d, J = 3.0 Hz, IH), 3.84 (s, 3H). ESI-MS (M+H+) = 176. |
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To the solution of 53 (4.90 g, 25.89 mmol) in THF/H2O was added 1N NaOH and the resulting mixture was heated at reflux for 60 min. The reaction mixture was cooled to 0 C., acidified with 1N HCl to ca. pH=3, and the mixture was partitioned between H2O and EtOAc and the combined organic layers were dried (MgSO4), filtered and concentrated to afford 4.25 g of 1-methyl-1H-indole-5-carboxylic acid (55). |
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With sodium hydroxide; In ethanol; water; for 1h;Heating / reflux; |
Step B. 1-Methyl-indole-5-carboxylic acid. A solution of <strong>[128742-76-7]1-methyl-indole-5-carboxylic acid methyl ester</strong> of Step A (2.5 g, 13.2 mmol) in ethanol (40 mL) containing 2.5 N aqueous NaOH (3:1, v/v) was heated at reflux for one hour. The reaction mixture was concentrated in vacuo, and the residue partitioned between diethyl ether and 1N HCl. The organic layer was washed with brine, dried over sodium sulfate, and evaporated to dryness to provide the title compound as a off-white solid (1.82 g). NMR (DMSO-d6, 300 MHz): delta 3.82 (s, 3H), 6.58 (dd, 1H), 7.42 (d, 1H), 7.48 (d, 1H), 7.75 (d, 1H), 8.22 (s, 1H), 12.38 (broad s, 1H). |
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