Hydrochloric Acid → 6-amino-2,3-dihydro-1H-indene-5-carboxylic acid

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Reaction Steps

Add 30% aqueous hydrogen peroxide solution (3 mL) to a solution of 1,5,6,7-tetrahydro-1-aza-s-indacene-2,3-dione (2.18 g, 11.66 mmol) in 2 N NaOH (23 mL) over a period of 5 minutes, stir the mixture at room temperature for 3 h. Add 1N hydrochloric acid to pH=5 and extract with ethyl acetate (3×20 mL). Wash with brine, dry the organic layer over anhydrous sodium sulfate, filter and remove the solvent under reduced pressure to afford 6-amino-indan-5-carboxylic acid (1.7 g, 86%). Dissolve in ethyl acetate (2 mL) and ethanol (2 mL) and add (trimethylsilyl) diazomethane (9.6 mL, 19.2 mmol, 2 M in hexane) at room temperature and stir the solution for 16 h. Remove the solvent under reduced pressure. Chromatograph the residue over silica gel, eluting with hexanes/ethyl acetate (9:1), to afford the title compound (1.19 g, 66%). 1H NMR (CDCl3, 300 MHz) δ 2.05 (quintuplet, J=7.3 Hz, 2H), 2.80 (q, J=7.7 Hz, 4H), 6.59 (s, 1H), 7.69 (s, 1H). MS (ES+): 192 (M+H).

Provenance & Evidence