Add a solution of 4-isopropoxycarbonylamino-indan-5-carboxylic acid methyl ester (570 mg, 2.1 mmol) in dimethylformamide (8.2 mL) to a suspension of sodium hydride 60% dispersion mineral oil (82 mg, 2.1 mmol) in dimethylformamide (8.2 mL) at 0° C. under an atmosphere of nitrogen and allow to reach room temperature over 1 h. Add ethyl 4-bromobutyrate (0.44 mL, 3.09 mmol) and stir at room temperature for 14 h, then heat at 65° C. for 2 h. Cool the mixture to room temperature, dilute with ethyl acetate, wash with 1M HCl, water, and brine. Dry the organic layer over anhydrous sodium sulfate, filter and remove the solvent under reduced pressure. Purify the residue by flash chromatography, eluting with hexanes/ethyl acetate, to provide the title compound (651 mg, 81%). 1H NMR (MeOD, 300 MHz) δ 1.03-1.34 (m, 9H), 1.85 (m, 2H), 2.10 (m, 2H), 2.30 (m, 2H), 2.82-3.01 (m, 4H), 3.32 (m, 1H), 3.68 (m, 1H), 3.86 (s, 3H), 4.08 (m, 2H), 4.91 (m, 1H), 7.19 (d, J=7.7 Hz, 1H), 7.77 (d, J=7.7 Hz, 1H). MS (ES+): 392 (M+H).
